# Patent

## Title
Zoom lens system

## Abstract

A zoom lens system is disclosed. The zoom lens system forms a final image of an object and a first intermediate real image between the object and the final image. The zoom lens system includes a first optical unit located between the object and the first intermediate real image. The first optical unit comprises at least one optical subunit which is moved to change the size (magnification) of the first intermediate real image. The zoom lens system also includes a second optical unit located between the first intermediate real image and the final image, at least a portion of which is moved to change the size (magnification) of the final image. The zoom lens system provides a wide zoom range of focal lengths with continuous zooming between the focal lengths.

## Background
CROSS-REFERENCE TO RELATED APPLICATION
This application is a Continuation-In-Part (CIP) application of U.S. patent application Ser. No. 10/622,914, filed Jul. 18, 2003 now U.S. Pat. No. 6,961,188, which claims the benefit of U.S. Provisional Application No. 60/397,882, filed Jul. 22, 2002, which application is specifically incorporated herein, in its entirety, by reference.


BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to optical lens systems for cameras and other optical devices, and, in particular, to high performance zoom lens systems that produce a high quality image over a full zoom range of focal lengths and are capable of being provided with an extremely large zoom ratio.
2. Description of Related Art
General Background of the Invention. The use of zoom lens systems for all types of photography, such as broadcast television, high definition television (“HDTV”), advanced television (“ATV”), video camcorders, film cinematography and still photography has become increasingly popular. As the use of zoom lens systems has increased, the demand for wider ranges of zooming capability, i.e. large zoom ratios, has also increased. For example, the zoom lens systems used in broadcast television have steadily increased in zoom ratio capability over the years to a maximum of about 101 to 1 at present but there is a demand for a still larger zoom ratio. While the focal length range of a conventional zoom lens system may be increased by the use of a drop-in extender or other multiplier, such as a broadcast television zoom lens system with a focal length range of 8.9 mm to 900 mm being increased to 17.8 mm to 1800 mm to increase the telephoto capability, this does not change the zoom ratio of about 101 to 1. Moreover, for broadcast television zoom lens systems there are somewhat different requirements for “studio” (indoor) or “outside broadcast” (outdoor) use concerning the focal length range and acceptable “f” numbers, whereby it has become conventional practice to employ two different zoom lens systems for indoor and outdoor broadcast television uses to maximize the capabilities for both types of uses.
Further, in addition to the demand and desirability of using zoom lens systems with wider ranges of focal lengths, such lenses must retain superior optical characteristics and performance that previously has been accomplished only by using separate objective lenses of different fixed focal lengths or zoom lens systems with a limited zoom ratio. As the zoom ratio increases, the difficulty in providing a high performance optical system with superior characteristics and performance also increases. Even most previously available zoom lens systems of a limited zoom range have one or more undesirable limitations such as the inability to focus adequately over the entire focal length range, the inability to focus on close objects, the lack of adequate optical performance over the entire focal length range and focus distance, the cost, the large size for the limited zoom range achieved and the like.
Still further, as the zoom range of a lens system increases, generally the length and weight increases whereby the difficulty in maintaining the lens and camera steady also increases. Therefore image stabilization also becomes an issue for the design of a practical zoom lens system having a large focal length range and zoom ratio.
Moreover, as the focal length range of a zoom lens system increases, generally the focusing problems also increase. Although close focusing at long focal lengths of the zoom range is not absolutely necessary, it is required at lesser focal lengths. In the past, continuous focusing over a considerable conjugate range from infinity to objects at a very short distance such as about 8 feet or less has been difficult to achieve. Further, the problem of “breathing” of the final image (where the perceived size changes as the focus distance is changed) at shorter focal lengths must be minimized to avoid, for example, one person disappearing from the scene as the focus is changed to another person at a different distance from the lens. These focus performance requirements, including maintaining the quality of the final image, tend to increase substantially the weight and cost of the zoom lens system unless the size can be minimized and performance maximized by the overall lens design, including glass selection.
Background Information Concerning Zooming. As discussed above, zoom lens systems with a wide-range of focal lengths are very desirable in numerous photographic applications, including broadcast television, cinematography and video and still photography. One standard zoom lens system used in these applications has a four-group PN(P or N)P structure, where P stands for a group of at least one lens element wherein the lens group has positive power, N stands for a group of at least one lens element wherein the lens group has negative power, and the groups are identified consecutively from the object space toward the image space, as is conventional. The front positive group is often called the focusing group because it can be moved for focusing the zoom lens system at any focal length position without the need to refocus for any other focal length of the zoom lens. The second negative group is the variator, and it induces significant magnification change during zooming. The third group, which can in general have either positive or negative power, is the compensator, and it is movable to insure that the image plane remains stationary. It also can provide some of the magnification change to effect zooming. The final positive fourth group is often called the prime lens group because it forms a sharp image.
This basic zoom lens system is suitable for zoom ratios of 50:1 or even more. As the zoom ratio is extended to about 100:1, however, the variator is required to change its object magnification to such an extent during zooming that aberrations become impracticably large and difficult to correct. In addition, at such large zoom ratios there is a very large change in entrance pupil location during zooming, and this tends to make the front group very large and difficult to correct. Another problem derives from the fact that, to reduce the aberration change that results from a large change of magnification, it is desirable that the variator have reduced optical powers. Weaker optical power, however, also increases the lens travel and length of the optical system. For a narrow field-of-view this would not be a problem, but, for a wide field-of-view, large motions lead to an increase in the principal ray heights at the rear portion of the lens system. Since the requirements for either the front or the rear of the lens system can be satisfied, but not simultaneously, this results in no ideal place for the aperture stop. If the stop is placed near the front of the lens, the front lens element diameters, and resultant aberrations, are reduced, and if the aperture stop is placed nearer to the rear part of the lens system, the rear lens diameters and resultant aberrations are decreased.
SUMMARY OF THE INVENTION
General Summary of the Invention. It is an object of the present invention to provide a zoom lens system that overcomes the problems and inefficiencies of prior zoom lens systems having large zoom ratios. A further object is to provide a zoom lens system with a wide zoom range of focal lengths and high performance characteristics for both indoor and outdoor use. A still further object of this invention is to provide a zoom lens system with a ratio of about 300 to 1 and a zoom range, for example, from about 7 mm to 2100 mm focal length, with continuous zooming between the focal lengths. Still another object of this invention is to provide a high performance zoom lens system with an optical system having a front zoom lens group for forming an intermediate image and a rear zoom lens group to magnify that image to thereby produce an extremely large zoom ratio. Still another object is to provide such a zoom lens system with optical image stabilization. Still another object is to provide such a zoom lens system with a focusing lens group capable of precise focusing over the entire focal length range of the zoom ratio.
Although of particular benefit for achieving large zoom ratios, the zoom lens systems of the invention can have conventional zoom ratios, e.g., zoom ratios associated with such consumer products as video camcorders, still cameras and the like. It is an additional object of the invention to produce zoom lens systems for these smaller zoom ratio applications.
Other and more detailed objects and advantages of the present invention will readily appear to those skilled in the art from the various preferred embodiments.
Summary of the Zoom Ratio Aspects of the Invention. The present invention overcomes the obstacles that currently limit zoom lens systems to a zoom ratio of about 101:1. The basic idea of the invention can be viewed as the use of a compound zoom lens system that consists of two separate zoom lens portions wherein the front zoom lens portion forms an intermediate image, and the rear zoom lens portion is a relay that transfers the intermediate image formed by the front zoom lens portion to the final image. The total zoom ratio of the complete compound zoom lens system is equal to the zoom ratio of the front zoom lens multiplied by the zoom ratio of the relay. Thus, if the zoom ratio of the front zoom lens portion is 20:1 and the zoom ratio of the relay is 15:1, then the zoom ratio of the entire compound zoom lens system is 300:1. The present invention can be used to achieve a zoom ratio of 300:1 or more, which greatly exceeds the practical limit of conventional zoom lens systems.



BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1-5 are optical diagrams of compound zoom lens systems of the present invention for describing some of the principles and variations in the moving and fixed units employed in the system and some of the possible embodiments of the invention, with FIGS. 1-3 illustrating a system having about a 300:1 zoom ratio, FIGS. 4A and 4B having about a 130:1 zoom ratio and FIGS. 5A and 5B having about a 13:1 zoom ratio in an ultra wide angle lens system;
FIGS. 6A and 6B are optical diagrams of another embodiment of the zoom lens system of the present invention using three moving zoom lens groups, with the three zoom groups positioned for a short focal length in FIG. 6A and for a long focal length in FIG. 6B;
FIGS. 7A and 7B are optical diagrams of another embodiment of the zoom lens system of the present invention using four moving zoom lens groups, with the four zoom groups positioned for a short focal length in FIG. 7A and for a long focal length in FIG. 7B;
FIGS. 8A and 8B are optical diagrams of another embodiment of the zoom lens system of the present invention using four moving zoom lens groups, with the four zoom groups positioned for a short focal length in FIG. 8A and for a long focal length in FIG. 8B;
FIGS. 9A and 9B are optical diagrams of another embodiment of the zoom lens system of the present invention using three moving zoom lens groups, with the three zoom groups positioned for a short focal length in FIG. 9A and for a long focal length in FIG. 9B;
FIGS. 10-62 are figures that all relate to a single embodiment of the zoom lens system of the present invention that has a zoom ratio of about 300:1, with FIG. 10 being an optical diagram of the entire lens system, FIGS. 11-30 comprising optical diagrams of the lens system in 20 different representative positions of the movable lens elements, FIGS. 31-34 comprising optical diagrams of only the lens elements of the focus unit in four of the representative positions, FIGS. 35 and 36 illustrating only the front two zoom lens groups in two of the representative positions, FIGS. 37 and 38 illustrating only the rear zoom lens group in two of the representative positions, FIGS. 39-58 comprising ray aberration diagrams for the same 20 representative positions of all of the lens elements illustrated in FIGS. 11-30, respectively, FIG. 59 comprising a graph of the focus cam movement relative to the focus distances from minimum (bottom) to infinity (top), FIG. 60 comprising graphs of the three zoom cam movements relative to the system focal lengths, FIG. 61 comprising a graph of the “f” numbers of the system at the final image relative to the system focal lengths, and FIG. 62 comprising a graph of the stop diameters relative to the system focal lengths;
FIGS. 63 and 64 are an optical diagram and ray aberration graphs, respectively, for another embodiment of the zoom lens system of this invention incorporating a binary (diffractive) surface;
FIGS. 65 and 66 are an optical diagram and ray aberration graphs, respectively, for still another embodiment of the zoom lens system of this invention incorporating a binary (diffractive) surface; and
FIGS. 67-70 are figures that relate to a still further embodiment of the invention having a zoom ratio of about 400:1 with FIGS. 67 and 68 being optical diagrams at focal lengths of 7.47 mm and 2983 mm, respectively, and FIGS. 69 and 70 being ray aberration graphs at focal lengths of 7.47 mm and 2983 mm, respectively;
FIGS. 71 and 72A-72D are optical diagrams for an example of still another embodiment of the zoom lens system of this invention incorporating a mirror for folding the lens for added compactness, with FIGS. 72A-72D showing the folded lens in a flat (unfolded) orientation for clarity, and illustrating various positions of the zoom groups;
FIGS. 73A-73C are optical diagrams for an example of an infrared (IR) embodiment of the zoom lens system of this invention, illustrating various positions of the zoom groups; and
FIGS. 74-76 are ray aberration graphs corresponding to the position of the zoom groups shown in FIGS. 73A-73C, respectively;
FIG. 77 illustrates an unfolded layout of a second example of an IR embodiment of the zoom lens system of this invention, with lens elements and surfaces identified;
FIGS. 78A-78F illustrate an unfolded layout of the second example IR embodiment at Zoom Positions Z1-Z6; and
FIGS. 79A-79F illustrate the diffraction modulation transfer function (MTF) of selected light rays for the second example IR embodiment at the zoom positions shown in FIGS. 78A-78F.



DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
In the following description of preferred embodiments, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the preferred embodiments of the present invention.
In accordance with its general aspects, the invention provides a zoom lens system for forming a final image of an object, said system forming a first intermediate real image between the object and the final image, said system comprising:
(a) a first optical unit (e.g., lens elements 8 through 15 in FIG. 10) located between the object and the first intermediate real image, said unit comprising at least one optical subunit which is moved to change the size (magnification) of the first intermediate real image (e.g., lens elements 8 through 11 are the primary source of magnification change for the first optical unit in FIG. 10); and
(b) a second optical unit (e.g., lens elements 26 through 33 in FIG. 10) located between the first intermediate real image and the final image at least a portion of which (e.g., one or more optical subunits or the entire second optical unit) is moved to change the size (magnification) of the final image (e.g., in FIG. 10, lens elements 26 through 28 of the second optical unit are moved to change the size of the final image).
Preferably, the zoom lens system includes one or more optical subunits in either or both of the first and second optical units which is moved to hold the axial position of the final image substantially stationary as the focal length of the system is changed (e.g., lens elements 12 through 15 are the primary source of this function in FIG. 10). Such a subunit, however, may not be needed in all cases, e.g., if the overall optical system has an axially movable sensor.
Preferably, in addition to the first and second optical units, the zoom lens system comprises a focus unit (e.g., lens elements 1 through 7 in FIG. 10), a pupil imaging unit (e.g., lens elements 16 through 25 in FIG. 10), and/or an image stabilization unit (e.g., lens elements 34 through 39 in FIG. 10).
Preferably, the focus unit is (1) positioned in front of the first optical unit, (2) comprises two optical subunits that are movable along the zoom lens system's optical axis (e.g., lens element 2 and elements 3 and 4 in FIG. 10), and/or (3) comprises seven or less lens elements.
Preferably, the image stabilization unit comprises (1) at least one lens element that is laterally movable off the system's optical axis (e.g., lens elements 34 through 36 in FIG. 10), and/or (2) at least one lens element that is movable along the optical axis (e.g., lens elements 37 through 39 in FIG. 10). The light passing through the system is preferably substantially collimated between said laterally and axially movable lens elements of the image stabilization unit.
In addition to the first intermediate real image, the zoom lens systems of the invention can form additional intermediate real images between the object and the final image. The systems can include additional optical units besides the first and second units for changing the sizes (magnifications) of those additional intermediate real images.
Preferably, the first intermediate real image is formed in an air space between the optical elements of the zoom lens system (e.g., the lens elements, prisms, folding mirrors or the like used in the system) and does not pass through any surface of an optical element during zooming. When more than one intermediate real image is formed, this is also preferably true for all of the intermediate images.
The first optical unit in combination with other units of the system can have the form of a conventional zoom lens. Similarly, the second optical unit in combination with other units of the system can have a conventional zoom lens form. The overall system can thus be viewed as a “compounding” of two conventional zoom lenses with, in accordance with the invention, control of pupil imaging between the compounded zoom lenses.
The overall system can also be viewed as a front zoom lens which forms an intermediate image and a relay system which receives the intermediate image and changes its magnification to form the final image.
These approaches for describing the zoom lens systems of the invention are used herein in the detailed discussions of various aspects of the invention. Although these approaches provide a convenient way of describing the invention, it is to be understood that the invention is not limited to these descriptions and various embodiments and applications of the invention may not be completely amenable to such descriptions.
In accordance with other aspects, the invention provides a zoom lens system for forming a final image of an object, said system having a range of focal lengths between a maximum focal length and a minimum focal length and forming at least a first intermediate real image between the object and the final image for all focal lengths within said range, said system comprising:
(a) a first lens unit having a focal length that is changed to change the size (magnification) of the first intermediate real image, said first lens unit being located between the object and the first intermediate real image for all focal lengths within said range; and
(b) a second lens unit for changing the size (magnification) of the final image, said second lens unit being located between the first intermediate real image and the final image for all focal lengths within said range.
In accordance with additional aspects, the invention provides a zoom lens system which comprises a variable focal length front lens unit which forms an intermediate real image and a variable magnification rear lens unit which forms an image (preferably, a real image) of the intermediate image.
In accordance with further aspects, the invention provides a compound zoom lens system that collects radiation from an object space and delivers the radiation to a final image in image space, said system comprising multiple zoom lens portions including a first zoom lens portion forming an intermediate image of the radiation from the object space and a last zoom lens portion forming the final image in the image space.
In accordance with still further aspects, the invention provides a zoom lens system for forming a final image of an object, said system having an optical axis, a front lens surface, an aperture stop, and a chief ray which crosses the optical axis at the aperture stop, said system comprising first and second lens units that are moved to change the focal length of the system, wherein:
(a) between the front lens surface and the final image, the chief ray crosses the optical axis at at least one other location besides said aperture stop for all focal lengths of the system; and
(b) the system forms an intermediate real image that is located between the first and second lens units for all focal lengths of the system.
Description of Some Zooming Principles and Systems of the Invention. There are some unique aspects to a compound zoom lens system (i.e., a front zoom/zoom relay system) that enables an extraordinarily high degree of optical correction to be achieved. Imagine for a moment a simplified scenario in which the complete zooming motion takes place in stages. In the first stage the relay is initially set at a short focal length position that provides a small magnification of the intermediate image. The object conjugate of the relay will then have a small numerical aperture NA and its image conjugate will have a large numerical aperture NA. (As conventionally defined, the numerical aperture “NA” is equal to the sine of the vertex angle of the largest cone of meridional rays that can enter or leave an optical system or element, multiplied by the refractive index of the medium in which the vertex of the cone is located; and in the lens system optical prescriptions set forth below the “f” number equals the inverse of twice NA, i.e. f=1/2×NA). Since the NA in object space for the relay is equal to the NA in image space for the front zoom lens portion, then it is clear that in this first stage, the front zoom lens portion need only be well corrected for a small NA.
In the second stage, the front zoom lens portion is stationary at its long focal length position, and the relay then zooms to magnify the intermediate image to a greater and greater extent. As the focal length of the system increases during this second stage, the image NA of the relay becomes smaller and the object NA of the relay becomes larger. Hence, the image NA of the front zoom lens portion must also become larger. However, at the same time, the radial part of the intermediate image that is actually used becomes smaller and smaller as the system focal length gets larger.
Thus, the front zoom lens portion need not be corrected for a simultaneously large intermediate image size and a large relative aperture (NA). Rather, it needs to be corrected for a large intermediate image size at a small aperture, and for a small intermediate image size at a large aperture. This makes the design of the front zoom lens portion considerably easier than the design of a traditional zoom lens system having the same zoom ratio as the front zoom lens system of the present invention.
Likewise, the relay need only be corrected for a large image NA and large object size at the small magnification end of its focal lengths. At the other end of its zoom range of focal lengths, the object size is small and the image NA is also small.
As discussed above, in addition to a front zoom lens portion and a relay, the zoom lens systems of the invention preferably also include a pupil imaging unit. This unit serves to image the exit pupil of the front zoom lens portion into the entrance pupil of the relay. By selecting the appropriate powers, not only can the lens diameters, and attendant aberrations, of the relay be minimized, but control of the exit pupil position of the system can be improved.
As also discussed above, the intermediate image formed by the front zoom lens portion is preferably located at a position where it does not pass through any lens surfaces as the system is zoomed from its minimum to its maximum focal lengths. By being between the front zoom lens portion and the rear relay, the intermediate image is automatically behind the axially moving lens unit or units that provide zooming in the front zoom lens portion and in front of any axially moving lens units that provide zooming in the rear zoom portion. Since in certain embodiments of the invention the intermediate image can move during zooming, the locations for the lens surfaces on either side of the intermediate image, whether those surfaces are fixed or moving, are preferably chosen so that notwithstanding the motion of the intermediate image, the surfaces remain spaced from the intermediate image throughout the zoom range of the system.
Various of the foregoing features of the invention are illustrated in FIGS. 1-3 for a PNPP-PNPP compound zoom lens system with a zoom ratio of about 300:1. As indicated in FIG. 1, this compound zoom lens system has a front zoom lens portion with a zoom ratio of about 20:1 and a rear zoom lens portion (relay) with a zoom ratio of about 15:1. The groups and their positive or negative power signs are also indicated in FIG. 1. In this compound zoom lens system, the relay is stationary as the front zoom lens portion is operated from its shortest focal length position (shown in FIG. 1) to its longest focal length position (shown in FIG. 2). Once the front zoom lens portion reaches its long focal length position, the relay begins to vary the magnification of the intermediate image to further increase the focal length of the compound system. FIG. 3 shows the system in its maximum focal length condition, in which the front zoom lens portion is at its maximum focal length position and the rear zoom (relay) lens portion is in its maximum magnification position.
FIGS. 1 and 2 show the small NA at the intermediate image plane and large NA at the final image plane that occurs during the initial phase of zooming from short to long. The size of the intermediate image is large during this phase, as shown in the figures. FIG. 3 shows that the NA becomes larger at the intermediate image and smaller at the final image at the longest focal length position.
Note that in this example there are 8 zoom lens groups, but only 4 of them are independently movable for zooming. The 1st, 4th, 5th, and 8th groups are all stationary with respect to the final image. During focusing, however, one or more of these groups can be made to move.
The scenario sketched out here is for exemplary purposes. In practice, the zooming motion need not be clearly divided into two stages, and as a result the relay or a part of it can move during the initial zooming stages and not just near the long end of the focal lengths.
The example of FIGS. 1-3 described above has a PNPP-PNPP construction in which the dash “-” signifies the end of the front zoom lens portion. Both the front zoom lens portion and rear zoom lens portion have variator and compensator zooming groups. One advantage of this configuration is that the intermediate image can be made absolutely stationary if desired. Rendering the image stationary will prevent it from passing through any optical surface that might reveal surface flaws and dust images that will appear at the final image. Using a four-group construction in the rear zoom lens portion also permits better control of the exit pupil position, which may be important for matching the telecentricity requirements of certain image sensors.
If movement of the intermediate image can be tolerated, then it is possible to eliminate one of the compensators. Removal of the rear compensator is preferred in this case because it only moves when the beam diameters are relatively small. The resulting construction will then be a PNPP-PNP configuration.
For both of these configurations care must be taken to match the exit pupil of the front zoom lens portion with the entrance pupil of the relay. For this purpose, an eyepiece-like group is beneficial for converting the diverging beams emanating from the intermediate image into approximately parallel beams entering a normal PNP- or PNPP-type zoom lens system corrected for infinite conjugates.
One aspect of high-speed (large aperture) ultra-wide-range of focal lengths compound zoom lens systems of this type is that the intermediate image and all of its image faults are highly magnified by the zoom groups in the relay at the long focal length position. This places stringent requirements on the correction of secondary color aberrations in the front zoom lens portion and especially the focusing group. In order to accomplish this correction, it is necessary to use at least one, and more likely several, fluor-crown glass elements. As an alternative, calcium fluoride or binary (diffractive) surfaces could also be used for this purpose.
A variety of binary (diffractive) surfaces (diffractive elements) can be used in the practice of the invention. For example, for certain applications, one or more diffractive optical elements of the type disclosed in U.S. Pat. No. 6,507,437, assigned to Canon, can be used, either alone or in combination with other approaches for correcting chromatic aberrations.
One big advantage of using a PNPP-PNPP or PNPP-PNP configuration over existing zoom lens systems is that both the front zoom lens portion and the rear zoom lens portion (relay) system can have very large zoom ratios. It is quite reasonable to have a zoom ratio of 20:1 or more for either the front zoom lens portion or the rear zoom lens portion in this case, so that a total zoom ratio of 400:1 or more is possible. However, if such a large zoom ratio is not required, it is possible to simplify the system significantly by instead using a relay with an NP configuration having two moving groups. Such a relay is very useful for large aperture applications with a total zoom ratio in the relay of about 3:1 to about 10:1. An example of a compound zoom lens system with a zoom ratio of about 130:1 having an about 20:1 zoom ratio PNPP front zoom lens portion and an about 6.5:1 zoom ratio relay is shown in FIGS. 4A and 4B. FIG. 4A illustrates the minimum focal length of about 7 mm and FIG. 4B illustrates the maximum focal length of about 900 mm. One disadvantage of this configuration is that the rearmost lens group is not stationary; hence it must be designed to withstand a considerable change of magnification at large apertures, which makes it somewhat difficult to design.
An even further simplified construction consisting of an NP front zoom lens portion and an NP rear zoom lens portion (relay) can also be designed, although the maximum zoom ratio in this case will be lowered. Clearly, the technique can be generalized to include a large number of combinations of various zoom lens arrangements for the front zoom lens portion and for the rear zoom lens portion. For example, a high zoom ratio, ultra wide angle zoom lens system can be constructed by using an NP, NPP or NPNP ultra wide angle front zoom lens portion having a zoom ratio of about 2:1 with an NP rear zoom lens portion (relay) having a zoom ratio of about 6.5:1. The result would be a compound zoom lens system with a zoom ratio of about 13:1 with a maximum full field of view of up to 100 degrees or more. FIGS. 5A and 5B illustrate a 4.4 mm-57.2 mm, f/3-f/7 compound zoom lens system with a zoom ratio of about 13:1 for a 2⁄3′′ sensor. The full-field angle at the wide-angle end of this compound zoom lens system is more than 102 degrees. Clearly, a PNPP-type rear zoom lens portion (relay) similar to the one used in FIGS. 1-3 could be used with this same ultra wide angle front zoom lens portion to yield an ultra wide angle compound zoom lens system with a zoom ratio of about 30:1.
The existence of an intermediate image is common to all of these configurations, and this offers some unique opportunities for aberration correction that are not typically available in zoom lens system types of the prior art. For example, aspheric surfaces placed on elements located near the intermediate image can have a strong impact on distortion and other field aberrations without disturbing the spherical aberration correction. Advantages of placing an aspheric surface in this area include that the tolerances are generous because the beam diameters are small, and the elements themselves are small. This means that the cost of using aspheric surfaces in this region is minimal.
Detailed Description of the Preferred Embodiments. As described above in the section entitled “Description of Some Zooming Principles and Systems of the Invention”, each of the herein disclosed embodiments of the present invention includes a front zoom lens portion and a rear zoom lens portion thereby forming a compound zoom lens system. An intermediate image is formed after the front zoom lens portion whereby the rear zoom lens portion functions as a zoom relay to magnify the intermediate image so as to produce the magnified final image for capturing by film or any other kind of light detector or capture device, such as a charge coupled device (CCD), in a camera. For purposes of this application, the term “camera” is used generically to describe any kind of light detecting or capturing device that may be placed after the lens system of the present invention, including a still, video or movie capture device, whether containing film, videotape, optical disk, CMOS, CCD or another storage medium, or an eyepiece or the human eye. Any such “camera” may include additional lens elements. At present it is contemplated that the front zoom lens portion will be comprised of two moving zoom lens groups and the rear zoom lens portion will be comprised of either one or two moving zoom lens groups, but it is to be understood that more or fewer moving zoom lens groups may be used without departing from the present invention. Also, at present it is contemplated that only one intermediate image will be formed in the entire compound zoom lens system but other embodiments of the present invention may form more than one intermediate image.
In addition to the front and rear zoom lens portions, the compound zoom lens system of the present invention preferably includes a focus lens group. It is preferred that the focus lens group be positioned at the front of the lens system, as shown by each of the embodiments disclosed herein, although it is possible to accomplish some and maybe all of the focusing elsewhere in the compound zoom lens system in other embodiments of the invention.
When a single intermediate image is formed in this compound zoom lens system, the final image is upside down and reversed left-to-right from the conventional orientation produced by an objective lens and therefore the image orientation must be accommodated by the camera. For a video camera using a single chip for the detector, it is possible to merely rotate the chip 180 degrees about the optical axis so that the chip reads the final image as though it is conventionally oriented. Another solution to the orientation problem for a video camera is to reverse the order in which the data is scanned, i.e. instead of from left-to-right and top-to-bottom the data can be read right-to-left and bottom-to-top to achieve the conventional orientation. Still another solution to the orientation problem for a video camera that uses a “frame store” feature to store an entire frame on a memory chip before it is transmitted for use is to merely transmit the stored frame from the frame store memory in the reverse order. For a movie film camera, the entire camera with the film magazine may be turned upside down to, as a result, run the film upwardly for correcting the image orientation. Another solution for the orientation of the image in a movie film camera used in the conventional manner and employing the present zoom lens system is to use digital compositing wherein the film is digitally scanned and then, for example, after digital manipulation the image is imposed on new film in the conventional orientation. The use of a prism in or in connection with the lens system of this invention will also correct the orientation of the final image. For this approach, care must be taken so that the prism will not cause excessive deterioration of the quality of the final image, especially for high performance applications of the present lens system.
Due to the compound zoom arrangement of the zoom lens system of the present invention, the body of the compound lens system will often be of substantial length and therefore any deflection or vibration of the lens system relative to the camera may cause unacceptable deflection or vibration of the final image in the camera. Thus, at least for compound zoom lens systems of the present invention having large zoom ratios, long focal lengths and/or substantial length, it is contemplated that an image stabilization arrangement will be employed. While electronic image stabilization may be appropriate for some video camera applications, for higher performance zoom lens system applications it is preferred that an optical image stabilization arrangement be included in the body of the compound zoom lens system and preferably near the camera end of the lens system, such as is included in the embodiment of FIGS. 10-62 described below.
Although it is more desirable to design and construct the compound zoom lens system of this invention as an integral unit for maximum performance, it is also possible to use two or more separable components to achieve the basic features. For example, a conventional zoom lens or a modified form thereof may be used as the front zoom lens portion and then the rear zoom lens portion may be comprised of a separate attachment that relays and varies the magnification of (e.g. zooms) the image formed by the front zoom lens portion, which image becomes the “intermediate” image, to form the final image. Thus, the front zoom lens portion will provide one zoom ratio and the rear attachment zoom portion will provide another zoom ratio. However, for such a combination, the pupil imaging should be controlled to obtain a final image of acceptable optical quality. Other such combinations of conventional and/or modified lens portions may also be used to provide the compound zoom lens system of the present invention.
FIGS. 6A through 9B illustrate optical diagrams for four different embodiments of the zoom lens system of the present invention. At the far right of each of the FIGS. 6A-9B the two rectangular blocks represent the prism blocks for a conventional 3 CCD 2⁄3′′ detector, which is part of the video camera and therefore not part of the zoom lens system.
The following tables list the lens system optical prescriptions, the variable thickness positions for various surfaces, and the focal lengths and magnifications for various surface groups for each of those four embodiments. For simplicity and clarity in view of the large number of surfaces and the small scale of the optical diagrams that include all of the elements, only some of the surfaces in FIGS. 6A through 9B that correspond to the surfaces set forth in the lens system optical prescriptions are identified. A more detailed explanation of the tables is provided following the tables.










TABLES FOR FIGS. 6A & 6B


LENS SYSTEM OPTICAL PRESCRIPTION
























Glass
Glass



Surface
Radius
Thickness
Index
Dispersion

















OBJECT
Infinity
Infinity



S1
925.010
10.000
1.90135
31.5



S2
280.601
20.595



S3
626.503
19.748
1.49699
81.6



S4
−2050.828
0.300



S5
−2871.294
12.027
1.49699
81.6



S6
−624.468
0.300



S7
266.779
14.079
1.49699
81.6



S8
497.283
0.300



S9
351.230
16.228
1.49699
81.6



S10
1246.212
0.300



S11*
185.443
25.083
1.49699
81.6



S12
839.856
Variable



S13
301.162
5.346
1.77249
49.6



S14*
71.693
15.360



S15
−3690.461
2.000
1.77249
49.6



S16
100.162
27.480



S17
−70.544
5.456
1.80400
46.6



S18
−3458.086
8.858
1.92286
18.9



S19
−125.683
Variable



S20
−257.845
12.063
1.49699
81.6



S21
−78.411
0.127



S22
149.706
13.001
1.49699
81.6



S23
−98.095
2.000
1.80349
30.4



S24
−266.962
0.100



S25
114.669
6.712
1.49699
81.6



S26
485.498
Variable



STOP
Infinity
24.165



S28*
−41.960
2.000
1.60311
60.7



S29
40.078
31.156
1.69894
30.1



S30
83.406
12.225



S31
−64.844
2.590
1.60311
60.7



S32
912.611
13.001
1.69894
30.1



S33
−52.224
24.076



S34
99.845
2.313
1.49699
81.6



S35
167.386
15.000



S36
155.608
14.122
1.49699
81.6



S37
−47.886
9.568
1.87399
35.3



S38
−67.571
0.018



S39
381.504
2.000
1.87399
35.3



S40
49.653
11.590
1.43875
95.0



S41
−583.112
43.970



S42*
50.132
14.235
1.43875
95.0



S43
482.784
Variable



S44
−23.147
2.000
1.69100
54.8



S45*
32.021
1.889



S46
52.655
21.412
1.84666
23.8



S47
−380.467
Variable



S48
102.416
11.302
1.49699
81.6



S49
−50.958
0.405



S50*
34.098
13.134
1.49699
81.6



S51
43.222
1.521



S52
58.738
10.784
1.49699
81.6



S53
−35.052
2.000
1.74319
49.3



S54
43.422
1.334



S55
57.389
10.079
1.49699
81.6



S56
−38.685
0.658



S57
−35.272
3.772
1.78472
25.7



S58
−56.940
0.500



S59
166.529
4.833
1.69100
54.8



S60
−100.192
0.250



S61
83.273
5.608
1.69100
54.8



S62
808.1
Variable



S63
Infinity
13.200
1.51680
64.1



S64
Infinity
2.000



S65
Infinity
33.000
1.60859
46.4



S66
Infinity
5.000



IMAGE
Infinity











Note: Maximum image diameter = 11.0 mm


*Surface profiles of aspheric surfaces S11, S14, S28, S42, S45 and S50 are


governed by the following conventional equation:






  Z
  =
  
    
      
        
          (
          CURV
          )
        
        ⁢
        
          Y
          2
        
      
      
        1
        +
        
          
            (
            
              1
              -
              
                
                  (
                  
                    1
                    +
                    K
                  
                  )
                
                ⁢
                
                  
                    (
                    CURV
                    )
                  
                  2
                
                ⁢
                
                  Y
                  2
                
              
            
            )
          
          
            1
            /
            2
          
        
      
    
    +
    
      
        (
        A
        )
      
      ⁢
      
        Y
        4
      
    
    +
    
      
        B
        ⁡
        
          (
          Y
          )
        
      
      6
    
    +
    
      
        (
        C
        )
      
      ⁢
      
        Y
        8
      
    
    +
    
      
        (
        D
        )
      
      ⁢
      
        Y
        10
      
    
  






where:


CURV = 1/(Radius of Surface)


Y = Aperture height, measured perpendicular to optical axis


K, A, B, C, D = Coefficients


Z = Position of surface profile for a given Y value,


as measured along the optical axis from the pole


(i.e. axial vertex) of the surface.












The coefficients for

The coefficients for




the surface S11 are:

the surface S42 are:
















K =
−0.2197954
K =
−0.0460624



A =
9.0593667e−009
A =
−2.6257869e−007



B =
1.7844857e−013
B =
−2.5945471e−010



C =
1.5060271e−017
C =
2.4316558e−013



D =
−9.7397917e−023
D =
−1.2995378e−016
















The coefficients for

The coefficients for




the surface S14 are:

the surface S45 are:
















K =
0.7048333
K =
0.0



A =
−3.0463508e−007
A =
−1.1056187e−005



B =
−1.1451797e−010
B =
2.8606310e−008



C =
3.4844023e−014
C =
−1.2655154e−010



D =
−2.2107339e−017
D =
2.2826095e−013
















The coefficients for

The coefficients for




the surface S28 are:

the surface S50 are:
















K =
−0.9252575
K =
0.0



A =
−1.8743376e−007
A =
−1.8976230e−006



B =
−1.0562170e−009
B =
1.2489903e−009



C =
2.8892387e−012
C =
−2.3703340e−012



D =
−3.6671423e−015
D =
3.0161146e−015













VARIABLE THICKNESS POSITIONS AND DATA
















P1
P2
P3
P4
P5
P6
P7
P8



















EFL
7.257
9.008
16.013
36.022
82.023
174.970
399.652
900.099


F/No.
1.450
1.450
1.450
1.450
1.450
2.000
4.000
5.000


S12
1.000
23.202
72.004
118.539
150.121
162.578
162.380
162.474


S19
243.711
218.457
160.764
96.265
43.111
0.500
57.093
0.500


S26
1.000
4.080
12.979
30.924
52.631
82.760
26.357
82.523


S43
142.978
142.908
142.764
142.760
142.409
140.110
89.130
81.860


S47
8.255
8.273
8.377
8.434
8.540
4.765
3.198
5.165


S62
19.000
19.000
19.000
19.000
19.000
25.160
77.703
83.508













Surface Groups
Focal Lengths














S1-S12
266.611



S13-S19
−46.300



S20-S26
91.566



S27-S43
55.841



S44-S47
−32.720



S48-S62
42.594











Surface Group Magnifications















Surfaces
P1 M′
P1 MP′
P2 M′
P2 MP′
P3 M′
P3 MP′
P4 M′
P4 MP′


















S1-S12
0.000
0.754
0.000
0.672
0.000
0.492
0.000
0.320


S13-S19
−0.238
7.670
−0.268
7.215
−0.374
6.275
−0.599
5.828


S20-S26
−0.350
0.876
−0.385
0.843
−0.495
0.746
−0.699
0.550


S27-S43
0.871
−1.159
0.870
−1.159
0.854
−1.159
0.844
−1.159


S44-S47
0.321
−2.846
0.322
−2.829
0.325
−2.794
0.327
−2.793


S48-S62
−1.170
−0.304
−1.170
−0.305
−1.170
−0.308
−1.170
−0.308


















Surfaces
P1 M′
P5 MP′
P6 M′
P6 MP′
P7 M′
P7 MP′
P8 M′
P8 MP′


















S1-S12
0.000
0.195
0.000
0.123
0.000
0.163
0.000
0.124


S13-S19
−1.012
7.410
−1.390
−119.200
−1.382
4.682
−1.386
−141.400


S20-S26
−0.945
−0.312
−1.275
−0.017
−0.715
0.599
−1.279
−0.014


S27-S43
0.834
−1.159
0.833
−1.159
0.774
−1.159
0.826
−1.159


S44-S47
0.330
−2.712
0.338
−2.278
0.769
−0.501
0.856
−0.451


S48-S62
−1.170
−0.313
−1.315
−0.361
−2.549
−0.731
−2.693
−0.727





Where, P1 M′ is lens group magnification of lens group which equals (entrance marginal ray angle)/exit marginal ray angle) and, P1 MP′ is lens group magnification which equals entrance principal ray angle/exit principal ray angle and so on, up to P8 M′ and P8 MP′; the first two characters representing position number, for example P1 M′ and P1 MP′ are for position 1.
















TABLES FOR FIGS. 7A & 7B


LENS SYSTEM OPTICAL PRESCRIPTION
























Glass
Glass



Surface
Radius
Thickness
Index
Dispersion

















OBJECT
Infinity
Infinity



S1
1273.174
10.255
1.80099
35.0



S2
475.265
1.538



S3
510.054
10.255
1.80099
35.0



S4
279.310
14.066



S5
459.720
19.331
1.49699
81.6



S6
21434.630
0.308



S7
800.941
10.451
1.49699
81.6



S8
27454.520
0.308



S9
309.779
13.334
1.49699
81.6



S10
634.103
0.308



S11
361.606
17.818
1.49699
81.6



S12
2023.306
0.308



S13*
172.930
25.353
1.49699
81.6



S14
568.502
Variable



S15
330.425
2.070
1.77249
49.6



S16*
73.838
18.829



S17
726.741
2.051
1.77249
49.6



S18
102.189
25.577



S19*
−73.683
6.352
1.77249
49.6



S20*
359.798
9.948
1.80809
22.8



S21
−116.821
Variable



S22
−176.211
5.797
1.49699
81.6



S23
−69.609
0.003



S24
144.415
20.317
1.49699
81.6



S25
−85.878
2.051
1.80349
30.4



S26
−282.651
0.000



S27
85.718
6.142
1.49699
81.6



S28
157.754
Variable



STOP
Infinity
22.498



S30*
−34.201
2.051
1.60729
59.4



S31
42.409
2.743
1.69894
30.1



S32
101.162
4.085



S33
−82.300
3.589
1.60311
60.7



S34
−90.892
3.444
1.69894
30.1



S35
−39.457
6.472



S36
51.200
7.178
1.49699
81.6



S37
55.671
15.382



S38
67.546
6.750
1.49699
81.6



S39
−47.804
3.076
1.87399
35.3



S40
−74.620
0.018



S41
95.357
3.076
1.87399
35.3



S42
35.060
30.000
1.43875
95.0



S43
−130.232
68.459



S44
Infinity
2.051



S45
Infinity
2.051
1.77249
49.6



S46
−341.189
8.763



S47*
−30.765
4.102
1.78469
26.3



S48
−36.525
21.109
1.51680
64.2



S49
−30.389
0.308



S50
−160.796
14.522
1.51680
64.2



S51
−66.413
0.308



S52
461.095
8.390
1.51680
64.2



S53
−109.832
7.208



S54*
247.113
3.076
1.84666
23.8



S55
57.348
10.868
1.49699
81.6



S56
−56.360
0.289



S57
−73.106
5.307
1.63853
55.4



S58
−44.690
Variable



S59
−28.736
3.076
1.83400
37.2



S60
115.838
2.771



S61
−31.347
2.871
1.83480
42.7



S62
−73.220
2.468



S63
−57.858
7.254
1.84665
23.9



S64
−24.994
0.005



S65
−29.067
2.871
1.80400
46.6



S66
−49.737
Variable



S67
507.291
2.051
1.74319
49.3



S68
104.703
7.178
1.49699
81.6



S69
−76.662
Variable



S70*
69.871
8.624
1.49699
81.6



S71
−663.734
8.908



S72
−155.686
3.076
1.84665
23.9



S73
−1137.705
0.202



S74
54.109
8.050
1.49699
81.6



S75
−73.493
0.393



S76
−66.184
2.871
1.74319
49.3



S77
−99.535
19.484



S78
Infinity
13.537
1.51633
64.1



S79
Infinity
2.051



S80
Infinity
33.841
1.60859
46.4



S81
Infinity
5.019



IMAGE
Infinity











Note: Maximum image diameter = 11.0 mm


*Surface profiles of aspheric surfaces S13, S16, S19, S20, S30, S47, S54 and


S70 are governed by the following conventional equation:






  
    
      
        
          Z
          =
          
          ⁢
          
            
              
                
                  (
                  CURV
                  )
                
                ⁢
                
                  Y
                  2
                
              
              
                1
                +
                
                  
                    (
                    
                      1
                      -
                      
                        
                          (
                          
                            1
                            +
                            K
                          
                          )
                        
                        ⁢
                        
                          
                            (
                            CURV
                            )
                          
                          2
                        
                        ⁢
                        
                          Y
                          2
                        
                      
                    
                    )
                  
                  
                    1
                    /
                    2
                  
                
              
            
            +
            
              
                (
                A
                )
              
              ⁢
              
                Y
                4
              
            
            +
            
              
                B
                ⁡
                
                  (
                  Y
                  )
                
              
              6
            
            +
            
              
                (
                C
                )
              
              ⁢
              
                Y
                8
              
            
            +
            
              
                (
                D
                )
              
              ⁢
              
                Y
                10
              
            
            +
          
        
      
    
    
      
        
          
          ⁢
          
            
              
                (
                E
                )
              
              ⁢
              
                Y
                12
              
            
            +
            
              
                (
                F
                )
              
              ⁢
              
                Y
                14
              
            
            +
            
              
                (
                G
                )
              
              ⁢
              
                Y
                16
              
            
          
        
      
    
  
   






where:


CURV = 1/(Radius of Surface)


Y = Aperture height, measured perpendicular to optical axis


K, A, B, C, D, E, F, G = Coefficients


Z = Position of surface profile for a given Y value,


as measured along the optical axis from the pole


(i.e. axial vertex) of the surface.











The coefficients for the
The coefficients for the 
The coefficients for the



surface S13 are:
surface S20 are:
surface S54 are:


















K =
−0.1600976
K =
0.0
K =
0.0



A =
6.9210418e−009
A =
3.4619978e−008
A =
−2.743254e−006



B =
2.2313210e−013
B =
4.2692157e−011
B =
−2.133804e−009



C =
1.1852054e−017
C =
−7.0823340e−014
C =
1.668568e−011



D =
−2.0918949e−021
D =
−2.3957687e−017
D =
−1.9544629e014



E =
2.2579263e−025
E =
5.4513203e−020
E =
0.0



F =
8.1799420e−030
F =
−1.4597367e−023
F =
0.0



G =
−1.2582071e−033
G =
−4.1263059e−027
G =
0.0















The coefficients for the
The coefficients for the 
The coefficients for the



surface S16 are:
surface S30 are:
surface S70 are:


















K =
0.9059289
K =
−0.8025959
K =
−2.3



A =
−4.3564263e−007
A =
−3.8556154e−007
A =
3.877213e−007



B =
−1.3760665e−010
B =
−5.4410316e−010
B =
4.916800e−010



C =
1.1349273e−014
C =
7.0427510e−012
C =
−1.461192e−012



D =
−3.8588303e−017
D =
−8.5740313e−015
D =
−3.258352e−017



E =
1.5211558e−020
E =
−5.2635786e−017
E =
4.664784e−018



F =
−5.1726796e−025
F =
1.0608042e−019
F =
−4.216175e−021



G =
−2.0900671e−027
G =
7.5783088e−023
G =
0.0















The coefficients for the
The coefficients for the




surface S19 are:
surface S47 are:

















K =
0.0
K =
0.0



A =
−6.5866466e−008
A =
−1.2184510e−005



B =
−3.2305127e−011
B =
1.2115245e−007



C =
−3.5095033e−014
C =
−3.0828524e−010



D =
4.0315700e−017
D =
−5.7252449e−014



E =
−6.1913043e−021
E =
0.0



F =
−2.4403843e−023
F =
0.0



G =
9.0865109e−027
G =
0.0













VARIABLE THICKNESS POSITIONS AND DATA















P1
P2
P3
P4
P5
P6
P7





EFL
 7.257
 12.152
 35.981
 82.040
145.068
736.934
2088.142


F/No.
 1.450
 1.450
 1.450
 1.450
 1.450
 7.200
 12.500


S14
 1.026
 51.867
122.026
160.824
167.824
157.900
 167.823


S21
262.564
202.199
103.948
 49.493
 0.000
 34.351
  0.000


S28
 1.563
 11.088
 39.178
 55.576
 97.329
 72.903
 97.329


S58
 8.616
 8.616
 8.616
 8.616
 8.616
 99.467
 105.316


S66
111.358
111.358
111.358
111.358
111.358
 53.699
  0.000


S69
 38.387
 38.387
 38.387
 38.387
 38.387
 5.195
 53.100













Surface Groups
Focal Lengths














 S1-S14
283.564



S15-S21
−52.598



S22-S28
102.619



S29-S58
51.668



S59-S66
−29.319



S67-S69
178.034



S70-S77
70.650











Surface Group Magnifications















Surfaces
P1 M′
P1 MP′
P2 M′
P2 MP′
P3 M′
P3 MP′
P4 M′
P4 MP′


















S1-S14
0.000
0.740
0.000
0.564
0.000
0.318
0.000
0.179


S15-S21
−0.260
7.365
−0.347
6.511
−0.644
6.193
−1.207
7.342


S22-S28
−0.369
0.833
−0.462
0.740
−0.736
0.466
−0.896
0.306


S29-S58
−2.392
−0.356
−2.392
−0.356
−2.392
−0.356
−2.392
−0.356


S59-S66
−0.282
25.995
−0.282
25.995
−0.282
25.993
−0.282
25.994


S67-S69
14680.000
0.231
14680.000
0.231
14680.000
0.231
14680.000
0.231


S70-S77
0.000
0.447
0.000
0.447
0.000
0.447
0.000
0.447
















Surfaces
P5 M′
P5 MP′
P6 M′
P6 MP′
P7 M′
P7 MP′





S1-S14
  0.000
 0.117
 0.000
 0.174
 0.000
 0.117


S15-S21
  −1.468
−19.350
 −1.150
14.886
−1.468
−19.350


S22-S28
  −1.303
 −0.101
 −1.065
 0.137
−1.303
 −0.101


S29-S58
  −2.392
 −0.356
 −2.392
−0.356
−2.392
 −0.356


S59-S66
  −0.282
 25.994
 −2.227
 0.319
−4.006
 0.300


S67-S69
14680.000
 0.231
271.410
 2.365
81.569
 1.386


S70-S77
  0.000
 0.447
 −0.001
−0.374
−0.005
 −1.131





Where, P1 M′ is lens group magnification of lens group which equals (entrance marginal ray angle)/(exit marginal ray angle) and, P1 MP′ is lens group magnification which equals entrance principal ray angle/exit principal ray angle and so on, up to P7 M′ and P7 MP′; the first two characters representing position number, for example P1 M′ and P1 MP′ are for position 1.
















TABLES FOR FIGS. 8A & 8B


LENS SYSTEM OPTICAL PRESCRIPTION
























Glass
Glass



Surface
Radius
Thickness
Index
Dispersion

















OBJECT
Infinity
Infinity



S1
−763.589
10.000
1.80099
35.0



S2
408.783
15.991



S3
1218.452
22.500
1.49699
81.6



S4
−948.218
0.100



S5
4440.119
19.600
1.49699
81.6



S6
−478.965
0.100



S7
355.717
24.300
1.49699
81.6



S8
−1197.673
0.100



S9
168.455
28.500
1.49699
81.6



S10
686.627
Variable



S11
240.261
2.650
1.77249
49.6



S12*
58.196
12.668



S13
307.706
2.900
1.77249
49.6



S14
100.924
19.233



S15
−70.095
3.050
1.77249
49.6



S16
236.075
14.100
1.84666
23.8



S17
−126.479
Variable



S18
−420.335
9.200
1.49699
81.6



S19
−81.355
0.126



S20
155.733
15.650
1.49699
81.6



S21
−98.523
2.750
1.80099
35.0



S22
−285.204
10.687



S23
76.070
7.900
1.49699
81.6



S24
118.043
Variable



STOP
Infinity
6.800



S26*
−35.243
6.500
1.60674
45.1



S27
55.360
0.106



S28
55.900
4.050
1.75519
27.5



S29
155.439
4.934



S30
−63.039
5.050
1.80518
25.4



S31
−39.609
2.240



S32
56.818
10.900
1.45599
90.3



S33
−43.388
2.150
1.80099
35.0



S34
−61.503
2.158



S35
107.501
2.100
1.80099
35.0



S36
29.896
11.600
1.49699
81.6



S37
166.103
78.890



S38
59.002
9.670
1.83741
25.4



S39
−405.826
20.924



S40
−22.134
19.750
1.80099
35.0



S41
−33.299
5.803



S42
−129.563
12.646
1.49699
81.6



S43
−52.914
0.152



S44
59.828
5.419
1.49699
81.6



S45
−209.080
0.100



S46
37.693
6.143
1.74099
52.7



S47
177.702
Variable



S48
−106.846
1.600
1.83480
42.7



S49
21.576
6.448



S50
−27.697
6.650
1.80099
35.0



S51
7367.260
0.829



S52
129.249
5.126
1.84583
24.0



S53
−46.358
Variable



S54
538.505
1.500
1.80099
35.0



S55
95.344
11.395
1.60300
65.5



S56
−60.650
Variable



S57
87.009
5.185
1.48749
70.2



S58
−165.647
1.434



S59
−85.357
1.500
1.80518
25.4



S60
−1236.715
0.100



S61
50.007
7.563
1.69472
54.5



S62
549.061
18.000



S63
Infinity
13.537
1.51633
64.1



S64
Infinity
2.051



S65
Infinity
33.841
1.60859
46.4



S66
Infinity
Variable



IMAGE
Infinity











Note: Maximum image diameter = 11.0 mm


*Surface profiles of aspheric surfaces S12 and S26 are


governed by the following conventional equation:






  Z
  =
  
    
      
        
          (
          CURV
          )
        
        ⁢
        
          Y
          2
        
      
      
        1
        +
        
          
            (
            
              1
              -
              
                
                  (
                  
                    1
                    +
                    K
                  
                  )
                
                ⁢
                
                  
                    (
                    CURV
                    )
                  
                  2
                
                ⁢
                
                  Y
                  2
                
              
            
            )
          
          
            1
            /
            2
          
        
      
    
    +
    
      
        (
        A
        )
      
      ⁢
      
        Y
        4
      
    
    +
    
      
        B
        ⁡
        
          (
          Y
          )
        
      
      6
    
    +
    
      
        (
        C
        )
      
      ⁢
      
        Y
        8
      
    
    +
    
      
        (
        D
        )
      
      ⁢
      
        Y
        10
      
    
  






where:


CURV = 1/(Radius of Surface)


Y = Aperture height, measured perpendicular to optical axis


K, A, B, C, D = Coefficients


Z = Position of surface profile for a given Y value,


as measured along the optical axis from the pole


(i.e. axial vertex) of the surface.


The coefficients for the surface S12 are:


K = 0.0


A = 1.3820532e−007


B = −2.7133115e−011


C = −9.2535195e−015


D = 3.3313103e−018


The coefficients for the surface S26 are:


K = −0.5520119


A = −1.0148386e−006


B = −5.9646048e−011


C = −1.3030573e−013


D = 3.2918363e−016









VARIABLE THICKNESS POSITIONS AND DATA















P1
P2
P3
P4
P5
P6
P7


















EFL
7.274
12.145
36.011
82.004
144.947
738.776
2095.406


F/No.
1.450
1.450
1.450
1.450
1.450
9.400
14.100


S10
3.154
50.878
126.861
163.460
167.963
167.403
168.654


S17
271.009
213.056
113.646
61.255
10.607
68.828
3.277


S24
2.350
12.345
35.982
51.876
97.922
40.276
104.616


S47
4.633
5.482
4.658
5.264
6.015
53.226
73.878


S53
105.364
104.868
105.482
104.798
103.775
14.725
2.050


S56
1.550
1.550
1.550
1.550
1.550
43.752
35.462


S66
4.969
4.799
4.853
4.815
5.202
4.818
5.114













Surface Groups
Focal Lengths














S1-S10
262.599



S11-S17
−50.895



S18-S24
98.756



S25-S47
37.686



S48-S53
−25.559



S54-S56
106.555



S57−S62
81.336











Surface Group Magnifications















Surfaces
P1 M′
P1 MP′
P2 M′
P2 MP′
P3 M′
P3 MP′
P4 M′
P4 MP′


















S1-S10
0.000
0.805
0.000
0.626
0.000
0.337
0.000
0.191


S11-S17
−0.248
7.962
−0.323
7.245
−0.625
7.155
−1.136
9.531


S18-S24
−0.349
0.734
−0.431
0.633
−0.680
0.394
−0.831
0.233


S25-S47
−1.752
−0.293
−1.612
−0.293
−1.683
−0.293
−1.613
−0.293


S48-S53
−0.505
5.934
−0.574
4.957
−0.532
5.900
−0.571
5.176


S54-S56
−1.558
1.108
−1.529
1.487
−1.539
1.120
−1.533
1.378


S57-S62
0.233
1.240
0.235
3.217
0.234
1.263
0.234
2.205
















Surfaces
P5 M′
P5 MP′
P6 M′
P6 MP′
P7 M′
P7 MP′
















S1-S10
0.000
0.130
0.000
0.184
0.000
0.120


S11-S17
−1.263
−8.111
−1.246
6.886
−1.285
−6.384


S18-S24
−1.324
−0.233
−0.748
0.350
−1.444
−0.301


S25-S47
−1.813
−0.293
−1.890
−0.293
−2.412
−0.293


S48-S53
−0.496
4.492
−3.524
0.483
−4.060
0.347


S54-S56
−1.600
1.750
−1.939
2.244
−1.904
1.880


S57-S62
0.230
−29.370
0.234
−0.833
0.231
−1.610





Where, P1 M′ is lens group magnification of lens group which equals (entrance marginal ray angle)/(exit marginal ray angle) and, P1 MP′ is lens group magnification which equals entrance principal ray angle/exit principal ray angle and so on, upto P7 M′ and P7 MP′; the first two characters representing position number, for example P1 M′ and P1 MP′ are for position 1.
















TABLES FOR FIGS. 9A & 9B


LENS SYSTEM OPTICAL PRESCRIPTION
























Glass
Glass



Surface
Radius
Thickness
Index
Dispersion

















OBJECT
Infinity
Variable



S1
Infinity
50.000



S2
−621.758
5.169
1.69350
53.2



S3
457.301
Variable



S4
−2452.883
4.799
1.80518
25.4



S5
599.599
Variable



S6
911.220
25.082
1.45599
90.3



S7
−497.020
0.100



S8
−2000.000
0.000



S9
1000.000
0.000



S10
2062.549
12.736
1.49699
81.6



S11
−1165.481
Variable



S12
963.440
19.740
1.49699
81.6



S13
−560.694
0.200



S14
382.994
19.312
1.49699
81.6



S15
−17187.180
0.200



S16
191.959
26.185
1.43875
95.0



S17
702.850
0.000



S18
324.818
Variable



S19
130.133
3.120
1.77249
49.6



S20*
40.551
15.089



S21
87.300
2.500
1.77249
49.6



S22
70.260
14.709



S23
−76.831
2.730
1.77249
49.6



S24
108.868
11.313
1.84666
23.8



S25
−166.114
Variable



S26
2466.515
12.326
1.49699
81.6



S27
−72.273
0.200



S28
114.639
17.864
1.49699
81.6



S29
−80.007
3.100
1.80099
35.0



S30
−402.245
0.200



S31
56.927
6.364
1.48749
70.2



S32
83.100
Variable



STOP
Infinity
6.855



S34*
−32.543
2.000
1.60311
60.7



S35
−178.894
11.407



S36
−41.737
3.274
1.84666
23.8



S37
−32.963
0.200



S38
49.510
12.747
1.49699
81.6



S39
−39.721
2.400
1.80099
35.0



S40
−53.729
0.200



S41
−163.422
1.850
1.80439
39.6



S42
26.111
9.221
1.49699
81.6



S43
−156.748
58.646



S44
44.245
2.533
1.80439
39.6



S45
1686.200
39.233



S46
−21.116
6.938
1.77249
49.6



S47
−21.969
14.095



S48
92.954
2.220
1.60300
65.5



S49
−59.449
0.200



S50
20.331
2.228
1.62229
53.2



S51
47.914
Variable



S52
−116.378
0.950
1.83480
42.7



S53
34.369
3.756



S54
−16.771
0.950
1.81600
46.6



S55
−36.990
1.142



S56
−21.552
17.886
1.78469
26.3



S57
−26.412
Variable



S58
−293.612
4.856
1.60311
60.7



S59
−78.391
0.200



S60
272.204
5.642
1.49699
81.6



S61
−126.344
0.200



S62
124.541
7.681
1.49699
81.6



S63
−102.092
2.500
1.80518
25.4



S64
−874.268
0.200



S65
400.000
0.000



S66
38.596
8.430
1.45599
90.3



S67
211.910
6.207



S68
Infinity
0.500



S69
123.725
2.000
1.81600
46.6



S70
39.478
7.176



S71
−84.356
2.000
1.74099
52.7



S72
36.196
18.326
1.84666
23.8



S73
210.724
0.984



S74
Infinity
7.645



S75
105.952
3.999
1.49699
81.6



S76
−91.250
0.200



S77
46.317
5.948
1.60300
65.5



S78
−69.543
1.500
1.84666
23.8



S79
166.511
22.000



S80
Infinity
13.200
1.51633
64.1



S81
Infinity
2.000



S82
Infinity
33.000
1.60859
46.4



S83
Infinity
0.000



S84
Infinity
0.000



IMAGE
Infinity











Note: Maximum image diameter = 11.0 mm


*Surface profiles of aspheric surfaces S20 and S34 are governed by the


following conventional equation:






  Z
  =
  
    
      
        
          (
          CURV
          )
        
        ⁢
        
          Y
          2
        
      
      
        1
        +
        
          
            (
            
              1
              -
              
                
                  (
                  
                    1
                    +
                    K
                  
                  )
                
                ⁢
                
                  
                    (
                    CURV
                    )
                  
                  2
                
                ⁢
                
                  Y
                  2
                
              
            
            )
          
          
            1
            /
            2
          
        
      
    
    +
    
      
        (
        A
        )
      
      ⁢
      
        Y
        4
      
    
    +
    
      
        B
        ⁡
        
          (
          Y
          )
        
      
      6
    
    +
    
      
        (
        C
        )
      
      ⁢
      
        Y
        8
      
    
    +
    
      
        (
        D
        )
      
      ⁢
      
        Y
        10
      
    
  






where:


CURV = 1/(Radius of Surface)


Y = Aperture height, measured perpendicular to optical axis


K, A, B, C, D = Coefficients


Z = Position of surface profile for a given Y value,


as measured along the optical axis from the pole


(i.e. axial vertex) of the surface.


The coefficients for the surface S20 are:


K = −0.3254663


A = −3.65160e−007


B = −1.14704e−010


C = −5.60564e−014


D = −5.86283e−018


The coefficients for the surface S34 are:


K = 0.348034


A = 1.350560e−006


B = 2.453070e−009


C = −2.820340e−012


D = 4.745430e−015









VARIABLE THICKNESS POSITIONS AND DATA














P1
P2
P3
P4
P5
P6



















EFL
7.278
7.278
7.278
8.817
12.199
18.641



F/No.
1.749
1.749
1.749
1.749
1.749
1.749



SO
Infinity
5322.600
2499.900
Infinity
Infinity
Infinity



S3
17.233
50.424
82.285
17.233
17.233
17.233



S5
3.856
8.913
13.211
3.856
3.856
3.856



S11
74.605
36.357
0.200
74.605
74.605
74.605



S18
0.200
0.200
0.200
26.070
64.733
106.272



S25
300.191
300.191
300.191
272.377
230.274
183.410



S32
1.334
1.334
1.334
3.266
6.708
12.035



S51
1.647
1.647
1.647
1.647
1.647
1.647



S57
80.778
80.778
80.778
80.778
80.778
80.778













VARIABLE THICKNESS POSITIONS AND DATA














P7
P8
P9
P10
P11
P12



















EFL
32.734
60.449
94.190
123.985
206.250
284.791



F/No.
1.749
1.749
1.890
2.020
2.160
2.700



SO
Infinity
Infinity
Infinity
Infinity
Infinity
Infinity



S3
17.233
17.233
17.233
17.233
17.233
17.233



S5
3.856
3.856
3.856
3.856
3.856
3.856



S11
74.605
74.605
74.605
74.605
74.605
74.605



S18
148.849
183.007
201.036
209.783
216.511
215.851



S25
132.062
85.948
57.616
42.322
21.856
15.570



S32
20.806
32.763
43.065
49.609
63.170
70.310



S51
1.647
1.647
2.130
3.050
8.806
15.438



S57
80.778
80.778
80.294
79.375
73.618
66.987













VARIABLE THICKNESS POSITIONS AND DATA













P13
P14
P15
P16
P17


















EFL
717.193
2092.160
2092.160
2092.160
2092.160



F/No.
5.200
13.750
13.750
13.750
17.490



SO
Infinity
Infinity
8708.000
4050.000
2499.900



S3
17.233
17.233
37.759
59.403
82.285



S5
3.856
3.856
7.178
10.305
13.211



S11
74.605
74.605
50.757
25.988
0.200



S18
211.275
208.261
208.261
208.261
208.261



S25
5.736
0.200
0.200
0.200
0.200



S32
84.680
93.262
93.262
93.262
93.262



S51
39.946
82.225
82.225
82.225
82.225



S57
42.480
0.200
0.200
0.200
0.200














Surface Groups
Focal Lengths














S2-S3
−379.209



S4-S5
−597.975



S6-S11
484.131



S12-S18
229.394



S2-S18
262.190



S19-S25
−49.050



S26-S32
79.931



S33-S51
41.254



S52-S57
−26.810



S58-S79
70.920











Surface Group Magnifications















Surfaces
P1 M′
P1 MP′
P2 M′
P2 MP′
P3 M′
P3 MP′
P4 M′
P4 MP′





S2-S3
0.000
1.732
0.066
1.710
0.129
1.696
0.000
1.971


S4-S5
0.599
1.754
0.594
1.563
0.59
1.425
0.599
2.388


S6-S11
2.150
0.529
2.229
0.608
2.304
0.682
2.150
0.374


S12-S18
−0.537
0.642
−0.537
0.642
−0.537
0.642
−0.537
0.53


S2-S18
0.000
1.030
−0.047
1.043
−0.094
1.058
0.000
0.934


S19-S25
−0.185
8.447
−0.185
8.447
−0.185
8.447
−0.206
7.952


S26-S32
−0.252
0.756
−0.252
0.756
−0.252
0.756
−0.252
0.731


S33-S51
−1.446
−0.378
−1.446
−0.378
−1.446
−0.378
−1.442
−0.378


S52-S57
−0.673
6.392
−0.673
6.392
−0.673
6.392
−0.676
6.392


S58-S79
−0.611
0.966
−0.611
0.966
−0.611
0.966
−0.611
0.966





Surfaces
P5 M′
P5 MP′
P6 M′
P6 MP′
P37 M′
P7 MP′
P8 M′
P8 MP′





S2-S3
0.000
2.695
0.000
6.440
0.000
−4.655
0.000
−1.279


S4-S5
0.599
−24.64
0.599
−0.414
0.599
0.216
0.599
0.403


S6-S11
2.150
−0.033
2.150
−1.271
2.150
−127.8
2.150
4.484


S12-S18
−0.537
0.365
−0.537
0.187
−0.537
0.004
−0.537
−0.147


S2-S18
0.000
0.788
0.000
0.633
0.000
0.473
0.000
0.341


S19-S25
−0.245
7.233
−0.31
6.531
−0.424
6.046
−0.601
6.421


S26-S32
−0.319
0.688
−0.386
0.622
−0.496
0.512
−0.646
0.362


S33-S51
−1.445
−0.378
−1.448
−0.378
−1.448
−0.378
−1.449
−0.378


S52-S57
−0.673
6.392
−0.671
6.392
−0.671
6.392
−0.67
6.392


S58-S79
−0.611
0.966
−0.612
0.966
−0.612
0.966
−0.612
0.966





Surfaces
P9 M′
P9 MP′
P10 M′
P10 MP′
P11 M′
P11MP′
P12 M′
P12MP′





S2-S3
0.000
−0.736
0.000
−0.549
0.000
−0.387
0.000
−0.365


S4-S5
0.599
0.468
0.599
0.496
0.599
0.522
0.599
0.526


S6-S11
2.150
3.296
2.150
2.964
2.150
2.701
2.150
2.668


S12-S18
−0.537
−0.234
−0.537
−0.279
−0.537
−0.330
−0.537
−0.338


S2-S18
0.000
0.265
0.000
0.225
0.000
0.180
0.000
0.173


S19-S25
−0.771
8.327
−0.894
11.79
−0.983
−18.95
−1.004
−14.68


S26-S32
−0.770
0.233
−0.846
0.152
−1.064
−0.084
−1.092
−0.107


S33-S51
−1.431
−0.378
−1.406
−0.378
−1.344
−0.378
−1.359
−0.378


S52-S57
−0.692
5.731
−0.728
4.790
−0.916
2.531
−1.194
1.491


S58-S79
−0.611
1.263
−0.611
2.227
−0.611
−2.992
−0.610
−1.604





Surfaces
P13M′
P13MP′
P14M′
P14MP′
P15M′
P15MP′
P16M′
P16MP′





S2-S3
0.000
−0.351
0.000
−0.348
0.041
−0.294
0.085
−0.24


S4-S5
0.599
0.529
0.599
0.529
0.596
0.529
0.593
0.529


S6-S11
2.150
2.646
2.150
2.642
2.199
2.691
2.250
2.742


S12-S18
−0.537
−0.344
−0.537
−0.345
−0.537
−0.345
−0.537
−0.345


S2-S18
0.000
0.169
0.000
0.168
−0.029
0.145
−0.061
0.12


S19-S25
−0.919
−5.386
−0.870
−3.955
−0.869
−3.955
−0.869
−3.955


S26-S32
−1.351
−0.287
−1.561
−0.395
−1.561
−0.395
−1.561
−0.395


S33-S51
−1.719
−0.378
−2.606
−0.378
−2.61
−0.378
−2.612
−0.378


S52-S57
−2.093
0.631
−3.758
0.316
−3.685
0.316
−3.626
0.316


S58–S79
−0.613
−1.659
−0.600
−7.955
−0.610
−7.955
−0.619
−7.955














Surfaces
P17M′
P17MP′















S2-S3
0.129
−0.183



S4-S5
0.590
0.528



S6-S11
2.304
2.795



S12-S18
−0.537
−0.345



S2-S18
−0.094
0.093



S19-S25
−0.869
−3.955



S26-S32
−1.561
−0.395



S33-S51
−2.612
−0.378



S52-S57
−3.629
0.316



S58-S79
−0.618
−7.955







Where, P1 M′ is lens group magnification of lens group which equals (entrance marginal ray angle)/(exit marginal ray angle) and, P1 MP′ is lens group magnification which equals entrance principal ray angle/exit principal ray angle and so on, upto P17 M′ and P17 MP′; the first two characters representing position number, for example P1 M′ and P1 MP′ are for position 1.



The group of elements defined by surfaces 69 through 73 is translated in a direction perpendicular to the optical axis to compensate for image vibration






In the lens system optical prescriptions provided above for each of the four embodiments, each surface of a lens element identified in the left hand column (“Surface”), the radius of that surface in the second column (“Radius”), the thickness on the optical axis between that surface and the next surface, whether glass or air, in the third column (“Thickness”), the refractive indices of the glass lens elements set forth in the fourth column (“Glass Index”), and the dispersion values for the lens elements (“Glass Dispersion”) set forth in the fifth column. The surface numbers in the first column “Surface” represent the surfaces numbered from left-to-right in the Figures in the conventional manner, namely from object space to image space.
In the left hand or “Surface” column of each lens system optical prescription provided above, the object to be imaged (e.g., photographed) is identified as “OBJECT”, the adjustable iris or stop is identified as “STOP”, and the final image is identified as “IMAGE”. The adjustable spaces between lens elements, such as on either side of movable zoom groups, are identified as “Variable” in the third or Thickness column of the lens system optical prescription. The EFL, Radius and Thickness dimensions are given in millimeters with the Thickness being the distance after that surface on the optical axis. When two surfaces of adjacent elements have the same radius and are coincident, as in a doublet or triplet, only one surface is identified in the first or “Surf” column.
For each of the four embodiments, Aspheric Coefficients for each of the aspheric surfaces are provided following the table of optical prescriptions.
In addition, for each of the four embodiments, tables of the variable thickness positions for various surfaces in each lens system optical prescription are provided which identify positions in the format “Px” for various surfaces (corresponding to entries in the Surface column of the optical prescription tables). The effective focal length (EFL) and the “f” number (F/No.) are also provided for each position.
Now each of the four embodiments of FIGS. 6A-9B will be described briefly to identify some of their differences. The embodiment of FIGS. 6A and 6B has an effective focal length range of about 7.25 mm to 900 mm, which provides a zoom ratio of about 125:1, while using three movable zoom lens groups, namely, Zoom 1, Zoom 2, and Zoom 3, with a focus lens group Focus at the object space end of the lens. The Zoom 3 group actually is comprised of two groups of elements that have a small amount of movement between surfaces S47 and S48 (compare FIGS. 6A and 6B). The embodiment of FIGS. 7A and 7B has an effective focal length range of about 7.27 mm to 2088 mm, which provides a zoom ratio of about 287:1, with four movable zoom lens groups (Zoom 1, 2, 3 and 4) and a focus lens group. The embodiment of FIGS. 8A and 8B has an effective focal length range of about 7.27 mm to 2095 mm, which also provides a zoom range of about 287:1, with four moving zoom lens groups and a focus lens group, which is very similar to the performance of the lens embodiment of FIGS. 7A and 7B. Similarly, the embodiment of FIGS. 9A and 9B has an effective focal length range of about 7.27 mm to 2092 mm, which also provides a zoom ratio of about 287:1, but uses only three moving zoom lens groups. Each of these four embodiments includes plural aspheric surfaces with the embodiments of the FIGS. 8A-8B and 9A-9B having only two such surfaces while the embodiment of FIGS. 7A-7B includes eight such surfaces, as indicated in the lens system optical prescriptions. The embodiment of FIGS. 9A and 9B also includes optical image stabilization lens elements near the camera end of the lens system similar to those included in the embodiment of FIGS. 10-62, which will be described below.
Detailed Description of the Embodiment of FIGS. 10-62. As noted above in the section entitled “Brief Description of the Drawings,” FIGS. 10-62 all relate to a single embodiment of the present invention that is directly and immediately applicable to the broadcast television market, although other markets are also available and various other embodiments and modifications of the invention may be more applicable to other markets. This embodiment of the compound zoom lens system of this invention has a zoom range of approximately 7 mm to 2100 mm in focal length, thereby providing a zoom ratio of about 300:1, which is more than three times the zoom ratio presently available in broadcast television zoom lens systems. Referring more particularly to the optical diagram of FIG. 10, the zoom lens system ZL is comprised of a focus lens group FG, a front zoom group FZG and a rear zoom group RZG. For the description of this embodiment, the lens system's stop is used as a divider between the “front” and “rear” of the lens. In terms of the terminology used in the “Description of Various Features of the Invention and the Disclosed Embodiments” set forth above, the focus lens group FG is the focus unit, the front zoom group FZG is the first optical unit, and the rear zoom group RZG includes a pupil imaging unit and an image stabilization unit, as well as the second optical unit.
The focus group FG is comprised of seven lens elements 1-7 with the front lens element 1 being stationary whereby the lens may be sealed at the front by fixing and sealing element 1 to the lens barrel (not shown). Lens element 2 comprises a first focus group FG1 and lens elements 3 and 4 comprise a second focus group FG2, both of which groups are independently movable for achieving the desired focus at each focal length. Elements 5-7 of the focus group FG are stationary.
The front zoom group FZG has a first zoom group ZG1 comprised of lens elements 8-11 and a second zoom group ZG2 comprised of lens elements 12-15, both of which zoom groups are independently movable. An iris or aperture stop STOP is positioned between the second zoom group ZG2 and a first group RG1 that forms the front portion of the rear zoom group RZG.
First group RG1 is comprised of lens elements 16-25, which remain stationary. The intermediate image is formed between lens elements 22 and 23 in the first group RG1. Although all of the lens elements 16-25 of this first group RG1 remain stationary at all times, the intermediate image moves along the optical axis between lens elements 22 and 23 at the longer focal lengths without touching either of those elements during the zooming of the lens system between the maximum and minimum focal lengths. The next lens group of the rear zoom group RZG is a third zoom group ZG3 comprised of lens elements 26-28 that are movable axially. Next within the rear zoom group RZG is a second group RG2 comprised of lens elements 29-33, which are stationary. The next elements in the rear zoom group RZG comprise a stabilization group SG having a radial decentralization group SG1 with lens elements 34-36 and an axially adjustable group SG2 with lens elements 37-39. The three zoom groups ZG1, ZG2 and ZG3 are independently movable along the optical axis for developing the full range of the focal lengths of about 7 mm to 2100 mm. Finally, although they are not part of the zoom lens system per se, FIG. 10 also illustrates two prism blocks 40 and 41 that emulate the conventional three CCD 2⁄3′′ detectors of a video camera for completing the optical diagram from object space to the final image.
The first or decentralization stabilization group SG1 is movable radially from the system's optical axis in any direction by about 0.5 mm or more in response to sensed vibrations of the lens to maintain the final image at the image plane in a stabilized location. The sensing of vibrations and the movement of group SG1 may be accomplished by any conventional means such as an accelerometer, a processor and a motor controlled by the processor in a closed loop system on a continuous basis. The second or axial stabilization group SG2 is axially movable for axial adjustment of about 1.25 mm or more in either direction for back focus adjustment. The second stabilization group SG2 may also be moved axially forward a greater amount for extended close focus at short focal lengths of the lens. The light rays between the first stabilization group SG1 and the second stabilization group SG2, i.e. between lens elements 36 and 37, are substantially collimated whereby the movements of those two groups for accomplishing stabilization, extending the close focus and adjusting the back focus do not cause any significant deterioration of the final image.
The decentralization stabilization group SG1 may also be used for creating special effects by causing the lens group SG1 to move radially in a shaking pattern to thereby simulate the shaking caused, for example, by an earthquake, a moving vehicle or explosions in a war movie. Such special effects can also be produced by moving the lens group SG2 axially in an oscillatory fashion, which slightly defocuses the picture. Radial movement of SG1 can also be combined with axial movement of SG2 to create a different special effect.
The complete lens design of the zoom lens system ZL for the embodiment of FIGS. 10-62 is set forth below in the tables generally entitled “Tables for FIGS. 10 thru 62.” The Lens System Optical Prescription table is similar to the foregoing lens prescriptions for the zoom lenses of FIGS. 6A-9B. A more detailed explanation of the tables is provided following the tables.










TABLES FOR FIGS. 10 thru 62


LENS SYSTEM OPTICAL PRESCRIPTION

























Semi


Surface
Radius
Thickness
Glass Name
Manufacturer
Aperture















OBJECT
Infinity
Variable


S1
Infinity
50.000


142.85


S2
−553.385
5.200
SLAL13
OHARA
111.77


S3
436.730
Variable


103.81


S4
−1545.910
4.900
STIH6
OHARA
102.97


S5
682.341
Variable


101.63


S6
1644.762
19.482
SFPL52
OHARA
101.59


S7
−467.261
0.730


101.38


S8
−2000.000
0.000


99.83


S9
4000.000
0.000


99.22


S10
1463.863
12.601
SFPL51
OHARA
98.87


S11
−1094.948
Variable


98.22


S12
1092.461
20.386
SFPL51
OHARA
100.60


S13
−480.155
0.730


101.05


S14
362.425
21.232
SFPL51
OHARA
101.85


S15
−14624.000
0.730


101.37


S16
181.063
24.150
SFPL53
OHARA
97.84


S17
477.885
0.000


96.42


S18
324.818
Variable


95.12


S19
208.678
3.120
SLAH66
OHARA
38.27


S20*
40.147
6.111


32.19


S21
67.136
3.150
SLAH59
OHARA
32.03


S22
56.870
14.527


30.64


S23
−98.690
2.730
SLAH66
OHARA
30.54


S24
90.992
12.5065
STIH53
OHARA
33.74


S25
−174.619
Variable


34.43


S26
764.771
14.926
SFPL52
OHARA
36.34


S27
−66.842
0.400


36.91


S28
133.738
17.704
SFPL51
OHARA
36.84


S29
−69.988
3.100
SLAM66
OHARA
36.62


S30
−1580.221
0.400


36.97


S31
65.214
9.613
SNSL36
OHARA
37.33


S32
129.561
Variable


36.67


STOP
Infinity
8.811


20.27


S34*
−36.392
2.044
SBSM14
OHARA
20.44


S35
−425.016
6.131


21.70


S36
−43.308
5.233
STIH53
OHARA
21.88


S37
−33.861
0.200


22.78


S38
47.203
13.980
SFPL51
OHARA
22.84


S39
−41.565
2.400
SLAM66
OHARA
22.59


S40
−56.845
0.200


22.47


S41
−109.533
1.950
SLAH63
OHARA
21.13


S42
31.532
10.159
SFPL51
OHARA
19.56


S43
−173.403
45.721


19.51


S44
47.891
4.513
SLAH53
OHARA
15.23


S45
−2514.287
41.843


14.84


S46
−23.807
9.483
SLAH59
OHARA
8.45


S47
−24.610
12.719


9.87


S48
61.223
3.114
SFPL51
OHARA
8.86


S49
−45.071
0.150


8.71


S50
24.918
3.242
SBSM9
OHARA
8.83


S51
−516.606
Variable


8.67


S52
−72.073
1.059
SLAL54
OHARA
7.15


S53
23.513
2.783


6.65


S54
−18.951
0.900
SLAH59
OHARA
6.54


S55
−57.174
1.347


6.84


S56
−21.150
21.292
SLAH60
OHARA
6.98


S57
−31.181
Variable


12.67


S58
−138.459
4.401
SBAL22
OHARA
23.12


S59
−75.648
0.300


23.54


S60
606.713
5.842
SFPL51
OHARA
23.89


S61
−96.488
0.300


23.97


S62
113.288
7.382
SFPL51
OHARA
23.55


S63
−97.742
2.500
STIH6
OHARA
23.30


S64
−366.723
0.300


23.05


S65
400.000
0.000


22.80


S66
38.760
8.585
SFPL52
OHARA
21.88


S67
269.438
5.901


21.07


S68
115.000
0.450


18.30


S69
94.072
1.770
SLAL54
OHARA
18.00


S70
35.982
7.000


16.65


S71
−90.502
2.010
SLAL8
OHARA
16.35


S72
29.972
6.150
STIH53
OHARA
16.01


S73
82.308
2.725


15.75


S74
79.000
9.670


15.78


S75
76.232
6.100
SPHM52
OHARA
15.87


S76
−75.003
0.761


15.66


S77
45.420
7.170
SFSL5
OHARA
14.38


S78
−45.317
1.500
STIH53
OHARA
13.58


S79
348.342
18.544


12.98


S80
Infinity
13.200
SBSL7
OHARA
10.30


S81
Infinity
2.000


9.00


S82
Infinity
33.000
BAF52
SCHOTT
8.70


S83
Infinity
0.000


5.69


S84
Infinity
0.000


IMAGE
Infinity
0.000










Note: Maximum image diameter = 11.0 mm


*Surface profiles of aspheric surfaces S20 and S34 are governed by the


following conventional equation:






  Z
  =
  
    
      
        
          (
          CURV
          )
        
        ⁢
        
          Y
          2
        
      
      
        1
        +
        
          
            (
            
              1
              -
              
                
                  (
                  
                    1
                    +
                    K
                  
                  )
                
                ⁢
                
                  
                    (
                    CURV
                    )
                  
                  2
                
                ⁢
                
                  Y
                  2
                
              
            
            )
          
          
            1
            /
            2
          
        
      
    
    +
    
      
        (
        A
        )
      
      ⁢
      
        Y
        4
      
    
    +
    
      
        B
        ⁡
        
          (
          Y
          )
        
      
      6
    
    +
    
      
        (
        C
        )
      
      ⁢
      
        Y
        8
      
    
    +
    
      
        (
        D
        )
      
      ⁢
      
        Y
        10
      
    
  






where:


CURV = 1/(Radius of Surface)


Y = Aperture height, measured perpendicular to optical axis


K, A, B, C, D = Coefficients


Z = Position of surface profile for a given Y value, as


measured along the optical axis from the pole


(i.e. axial vertex) of the surface.












The coefficients for

The coefficients for




the surface S20 are:

the surface S34 are:
















K =
−0.3564030
K =
0.4304790



A =
−8.06827e−07
A =
9.57697e−07



B =
−2.15109e−10
B =
1.31318e−09



C =
−6.36649e−14
C =
−1.45592e−12



D =
−3.89379e−18
D =
3.19536e−15













VARIABLE THICKNESS POSITIONS AND DATA















P1
P2
P3
P4
P5
P6
P7


















EFL
7.391
8.820
12.231
19.219
32.730
64.634
−93.220


F/No.
1.949
1.949
1.949
1.949
1.949
1.949
2.010


S0
Infinity
Infinity
5322.630
2499.896
Infinity
5322.630
Infinity


S3
19.882
19.882
49.699
78.333
19.882
49.699
19.882


S5
5.690
5.690
10.880
15.384
5.690
10.879
5.690


S11
71.522
71.522
36.516
3.376
71.522
36.516
71.522


S18
1.350
26.428
67.051
110.745
155.094
189.151
203.856


S25 
319.660
292.522
247.857
197.854
142.790
92.653
65.474


S32
9.625
11.684
15.727
22.036
32.751
48.830
61.304


S51
1.498
1.498
1.498
1.498
1.498
1.498
2.823


S57
63.257
63.257
63.257
63.257
63.257
63.257
61.933












VARIABLE THICKNESS POSITIONS AND DATA















P8
P9
P10
P11
P12
P13
P14


















EFL
145.184
206.228
490.401
717.511
2065.045
−3694.934
−920.968


F/No.
2.090
2.360
2.840
5.600
13.064
13.064
13.064


S0
5322.630
Infinity
5322.630
Infinity
Infinity
8708.002
4050.000


S3
49.699
19.882
49.699
19.882
19.882
38.428
57.882


S5
10.879
5.690
10.879
5.690
5.690
9.057
12.294


S11
36.516
71.522
36.516
71.522
71.522
49.608
26.917


S18
210.392
215.814
218.877
223.339
224.980
224.980
224.980


S25
50.046
33.074
24.338
10.235
1.719
1.719
1.719


S32
70.197
81.746
87.419
97.063
103.934
103.934
103.934


S51
4.711
9.572
14.559
31.080
63.536
63.536
63.536


S57
60.044
55.183
50.196
33.675
1.220
1.220
1.220












VARIABLE THICKNESS POSITIONS AND DATA














P15
P16
P17
P18
P19
P20

















EFL
−509.031
−1739.084
−387.928
7.227
114.357
377.554


F/No.
16.750
5.600
5.600
1.949
2.010
2.360


S0
2499.896
5322.630
2499.896
2499.896
2499.896
2499.896


S3
78.333
49.699
78.333
78.333
78.333
78.333


S5
15.384
10.879
15.384
15.384
15.384
15.384


S11
3.376
36.516
3.376
3.376
3.376
3.376


S18
224.980
223.339
223.339
1.350
203.856
215.814


S25
1.719
10.235
10.235
319.660
65.474
33.074


S32
103.934
97.063
97.063
9.625
61.304
81.746


S51
63.536
31.080
31.080
1.498
2.823
9.572


S57
1.220
33.675
33.675
63.257
61.933
55.183













Surface Groups
Focal Lengths














S2-S3
−349.648



S4-S5
−581.962



S6-S7
798.201



S10-S11
1258.758



S12-S13
672.072



S14-S15
709.848



S16-S17
646.676



S19-S20
−64.565



S21-S22
−526.211



S23-S25
−554.999



S26-S27
135.208



S28-S30
113230.702



S31-S32
240.348



S34-S35
−65.863



S36-S37
144.623



S38-S40
60.255



S41-S43
−70.987



S44-S45
58.010



S46-S47
205.873



S48-S49
52.593



S50-S51
38.634



S52-S53
−27.000



S54-S55
−34.933



S56-S57
−2495.053



S58-S59
284.851



S60-S61
167.476



S62-S64
292.466



S66-S67
97.878



S69-S70
−90.217



S71-S73
−72.295



S75-S76
61.902



S77-S79
1261.227



S80-S81
Infinity



S82-S83
Infinity










The Lens System Optical Prescription table comprises the “Listing” for the lens specification and numerically lists each lens “SURFACE” in the left-hand column, but also includes dummy surfaces used in the design such as dummy surfaces S1, S8, S9, S18, S65, S74 and S84. The second column “Radius” lists the radius of the respective surfaces with a negative radius indicating that the center of curvature is to the left. The third column “Thickness” lists the thickness of the lens element or space from that surface to the next surface on the optical axis. The fourth column “Glass Name” lists the type of glass and the fifth column “Manufacturer” lists the manufacturer of each glass material. The fifth column “Semi Aperture” provides a measurement of half the aperture diameter for each lens element.
In the left-hand column the legend “OBJECT” means the object to be imaged (e.g., photographed), the legend “STOP” means the iris or stop, and the legend “IMAGE” means the final image. Each of the surfaces is identified by a numeral preceded by “S” to distinguish the surfaces from the numerals that identify the lens elements set forth on the subsequent pages comprising the 39 glass lens elements described above with respect to FIG. 10 and prisms 40 and 41 of the detector.
It should be noted that each of the thickness dimensions set forth in the third column of the table listing the surfaces is the element thickness or air space along the optical axis for the zoom lens system ZL set to the shortest focal lens (7.39 mm EFL) and focused at infinity. The air spaces adjacent the moving lens groups obviously will change in “thickness” for other focal lengths and focus distances.
For each aspheric surface, Aspheric Coefficients are provided following the table of optical prescriptions.
FIGS. 11-30 illustrate 20 representative positions for the zoom lens system of FIG. 10. These 20 positions are listed in the following Table of Lens Positions:










TABLE OF LENS POSITIONS









Paraxial EFL (mm)

Focus Distance (mm) To Object*













@ Infinity Focus
“F” No.
INF.
8758
5372
4100
2550
















7.3909
1.95
1



18


8.8200
1.95
2


12.1938
1.95


3


18.6371
1.95




4


32.7300
1.95
5


60.2959
1.95


6


93.2199
2.01
7



19


127.2902
2.09


8


206.2278
2.36
9



20


297.4279
2.84


10


717.5114
5.60
11

16

17


2065.0447
13.06
12
13

14
 15#





*The Focus Distance is measured to the Object from the first refractive surface of the zoom lens system.


#The “F” No. equals 16.75 at this position.






The twenty (20) positions were selected as representative of extreme positions of focal length and focus distance, as well as intermediate positions, for establishing the representative performances of the zoom lens system ZL of FIG. 10. In other words, position 1 is at the minimum paraxial focal length (wide angle) of about 7.4 mm and focused at infinity whereas position 18 is focused at 2550 mm (about eight feet) for the same focal length. Similarly, position 12 represents the longest paraxial focal length of about 2065 mm at infinity focus whereas position 15 represents the focus at 2550 mm at the same paraxial focal length. The paraxial EFL in the first column is at infinity focus. The “f” numbers are at any given focus and at full aperture. The 12 different focal lengths provide representative focal lengths over the full range of the zoom lens system ZL. Also, it should be noted that the actual field of view as a result of distortion and the available physical overtravel of the zoom groups beyond data in the lens system optical prescription set forth below produces an apparent focal length range of substantially 7.0 mm to 2100 mm, i.e. a zoom ratio of about 300:1, with the distortion primarily influencing the reduction in the minimum paraxial EFL and the overtravel primarily influencing the increase in the maximum paraxial EFL. At 2100 mm EFL with focus set at eight feet, the magnification is about 1.33:1.00 (object to image size). The nominal lens design for the embodiment of FIGS. 10-62 as reflected in the lens optical prescription tables for FIGS. 10-62 is given at 77° F. (25° C., 298 K) and standard atmospheric pressure (760 mm Hg).
Referring now to FIGS. 11-30, the twenty positions 1-20 set forth in the foregoing lens system optical prescription and the preceding TABLE OF LENS POSITIONS are shown in that order. For example, FIG. 11 is an optical diagram of the lens elements in Position 1, namely, a paraxial effective focal length (EFL) of 7.391 mm and focused at infinity, wherein the first and second focus groups FG1 and FG2 are closely separated, the first and second zoom groups ZG1 and ZG2 are widely separated, and the third zoom group ZG3 is in its most forward position. On the other hand, FIG. 25 is the optical diagram representing Position 15 with the largest focal length and shortest focus distance, wherein the first and second focus groups FG1 and FG2 are both in their rearmost position, the first and second zoom groups ZG1 and ZG2 are in a closely spaced position but intermediately spaced between adjacent lens groups, and the third zoom group ZG3 is in the rearmost position.
FIGS. 31-34 are enlarged optical diagrams of only the seven focus group FG elements 1-7 and illustrate representative Positions 1, 18, 12 and 15, respectively. It should be noted that while the lens element positions in FIGS. 32 and 34 are the same, representing the focus distance of 2550 mm, the ray tracings are different because of the difference in the paraxial focal lengths from the minimum of about 7.4 mm in FIG. 32 to the maximum of about 2065 mm in FIG. 34.
FIGS. 35 and 36 are enlarged optical diagrams illustrating the last lens element 7 of the focus group FG and the first and second zoom groups ZG1 and ZG2 in Positions 1 and 12, respectively, for the minimum and maximum paraxial focal lengths, respectively. Similarly, FIGS. 37 and 38 represent the rear zoom group RZG with the third zoom group ZG3 in the forwardmost and rearmost Positions 1 and 12 representing the minimum and maximum paraxial focal length positions, all respectively.
Referring now to FIGS. 39-58, the ray aberration graphs for Positions 1-20, respectively, are shown in a conventional manner by five separate graphs with the maximum field height at the top and zero field height at the bottom and for five wavelengths, as listed thereon. As will readily appear to those skilled in the art, these performance curves establish that in all 20 positions the zoom lens system performs exceptionally well for current broadcast television NTSC quality and exceptionally well for HDTV broadcast television quality. While FIG. 50 representing Position 12, illustrates wide variations in the ray aberrations at this focal length and focused at infinity, the performance is satisfactory because the modulation transfer function is close to the diffraction limit. Similarly, FIGS. 52 and 53, representing Positions 14 and 15, respectively, illustrate widely varying ray aberrations but are still acceptable relative to diffraction limits for these close focus and long focal length positions.
Referring now to FIG. 59, the cam graph for the first and second focus groups FG1 and FG2 are shown (left and right, respectively) for the full range of focus travel thereof from infinity to close focus, with object space being to the left. The first and second focus groups FG1 and FG2 move separately and not at precisely the same rate, even though the solid cam lines in FIG. 59 look nearly parallel. The crosshatched portions at the top and bottom of FIG. 59 allow for temperature changes, manufacturing tolerances and fabrication adjustments. Similarly, FIG. 60 illustrates the cam graphs for the three zoom groups ZG1, ZG2 and ZG3 from left to right, respectively, and it is readily apparent that all three zoom groups move independently, although coordinated to achieve the desired focal lengths continuously over the entire range. FIG. 61 is a graph of the “f” number of the open stop relative to the paraxial effective focal length. Similarly, FIG. 62 is a graph of the full aperture full stop diameter relative to the paraxial effective focal length throughout the full range thereof.
DETAILED DESCRIPTION OF OTHER EMBODIMENTS
FIGS. 63 and 64 illustrate an example of another embodiment of the present invention. This embodiment of the zoom lens system is very similar to the embodiment of FIGS. 8A and 8B, except that a binary (diffractive) surface is provided. Specifically, a binary surface is provided on the front surface (surface No. 3 in the prescription) of the second lens element. The lens system optical prescription is set forth below in the tables generally entitled “Tables for FIGS. 63 and 64.” A more detailed explanation of the tables is provided following the tables.










TABLES FOR FIGS. 63 and 64


LENS SYSTEM OPTICAL PRESCRIPTION























Glass



Surface
Radius
Thickness
Name







OBJECT
Infinity
Infinity



S1
−731.222
10.000
LASF32



S2
390.798
15.991



S3#
827.075
22.500
BK7



S4
−1021.418
0.100



S5
−1257.463
−19.600
BK7



S6
−780.160
0.100



S7
436.979
24.300
BK7



S8
−835.454
0.100



S9
−170.301
28.500
BK7



S10
655.827
Variable



S11
278.083
2.650
S-LAH66



S12*
60.022
−12.668



S13
277.706
2.900
S-LAH66



S14
98.325
−19.233



S15
−70.105
3.050
S-LAH66



S16
234.965
−14.100
S-TIH53



S17
−127.001
Variable



S18
−404.763
9.200
S-FPL51



S19
−80.933
0.126



S20
−157.360
−15.650
S-FPL51



S21
−99.532
2.750
S-LAM66



S22
−284.625
−10.687



S23
76.300
7.900
S-FPL51



S24
−118.669
Variable



STOP
Infinity
6.800



S26*
−34.999
6.500
BAF4



S27
54.435
0.106



S28
55.347
4.050
S-TIH4



S29
−158.504
4.934



S30
−64.093
5.050
S-TIH6



S31
−39.812
2.240



S32
56.945
−10.900
S-FPL52



S33
−43.914
2.150
S-LAM66



S34
−61.923
2.158



S35
−106.356
2.100
S-LAM66



S36
30.350
−11.600
S-FPL51



S37
−151.277
78.890



S38
57.056
9.670
SF6



S39
−603.641
20.924



S40
−22.693
−19.750
S-LAM66



S41
−34.224
5.803



S42
−129.563
−12.646
S-FPL51



S43
−52.914
0.152



S44
59.828
5.419
S-FPL51



S45
−209.080
0.100



S46
37.693
6.143
S-LAL61



S47
−177.702
Variable



S48
−106.846
−1.600
S-LAH55



S49
21.S76
6.448



S50
−27.697
6.650
S-LAM66



S51
7367.260
0.829



S52
−129.249
5.126
S-TIH53



S53
−46.358
Variable



S54
538.505
−1.500
S-LAM66



S55
95.344
−11.395
S-PHM53



S56
−60.650
Variable



S57
87.009
5.185
S-FSL5



S58
−165.647
−1.434



S59
−85.357
−1.500
S-TIH6



S60
−1236.715
0.100



S61
50.067
7.563
S-LAL14



S62
539.692
−18.000



S63
Infinity
−13.537
S-BSL7



S64
Infinity
2.051



S65
Infinity
33.841
BAF52



S66
Infinity
Variable



IMAGE
Infinity











Note: Maximum image diameter = 11.0 mm


*Surface profiles of aspheric surfaces S12 and S26 are governed by


the following conventional equation:






  Z
  =
  
    
      
        
          (
          CURV
          )
        
        ⁢
        
          Y
          2
        
      
      
        1
        +
        
          
            (
            
              1
              -
              
                
                  (
                  
                    1
                    +
                    K
                  
                  )
                
                ⁢
                
                  
                    (
                    CURV
                    )
                  
                  2
                
                ⁢
                
                  Y
                  2
                
              
            
            )
          
          
            1
            /
            2
          
        
      
    
    +
    
      
        (
        A
        )
      
      ⁢
      
        Y
        4
      
    
    +
    
      
        B
        ⁡
        
          (
          Y
          )
        
      
      6
    
    +
    
      
        (
        C
        )
      
      ⁢
      
        Y
        8
      
    
    +
    
      
        (
        D
        )
      
      ⁢
      
        Y
        10
      
    
  






where:


CURV = 1/(Radius of Surface)


Y = Aperture height, measured perpendicular to optical axis


K, A, B, C, D = Coefficients


Z = Position of surface profile for a given Y value, as measured


along the optical axis from the pole


(i.e. axial vertex) of the surface.












The coefficients for

The coefficients for




the surface S12 are:

the surface S26 are:
















K =
0.01925737
K =
−0.5574845



A =
−1.3531387e−007
A =
−1.0833227e−006



B =
−1.5274225e−011
B =
−9.1904879e−011



C =
−2.0209982e−014
C =
−1.4775967e−013



D =
5.4753514e−0i8
D =
6.5701323e−016











#Surface profile of binary surface S3 is governed by the


following conventional equation:


Added Phase = A1p2 + A2p4 + A3p6 + A4p8 + A5p10


where: A1, A2, A3, A4 and A5 are coefficients and p is the normalized


radial coordinate at the surface.


The normalizing factor is set at unity and the p's become simply


radial coordinates.


A1 = −0.14123699


A2 = −8.7028052e−007


A3 = −1.2255122e−010


A4 = 5.9987370e−015


A5 = −1.2234791e−019









VARIABLE THICKNESS POSITIONS AND DATA















P1
P2
P3
P4
P5
P6
P7


















EFL
7.264
−12.117
35.980
81.979
−145.198
729.922
2100.036


F/No.
−1.450
−1.450
−1.450
−1.450
−1.450
9.400
−14.100


S10
3.154
50.878
−126.861
−163.460
−167.963
−167.403
168.654


S17
271.009
213.056
−113.646
61.255
−10.607
68.828
3.277


S24
2.350
−12.345
35.982
51.876
97.922
40.276
−104.616


S47
4.632
5.482
4.658
5.264
6.015
53.226
73.878


S53
−105.364
−104.868
−105.482
−104.798
−103.775
−14.725
2.050


S56
−1.550
−1.550
−1.550
−1.550
−1.550
43.752
35.462


S66
4.969
4.799
4.853
4.815
5.202
4.818
5.114









The prescription of binary surface 3 is included following the lens system optical prescription table listed above. The binary surface 3 adds phase to the wavefront. By providing binary surface 3, the second through fifth lens elements 2, 3, 4 and 5 in the focus portion of the lens can be made from relatively inexpensive glass, such as BK7, rather than expensive optical glass having abnormal dispersion characteristics, such as SFPL 51. While it is advantageous to include this binary surface 3 near the front of the lens system where the axial beam diameters are largest, it will readily appear to those skilled in the art that the binary (diffractive) surface may be provided elsewhere and that more than one such surface may be provided. Other methods of aberration correction may also be used advantageously. It should be noted that this embodiment also incorporates two aspheric surfaces 12 and 26.

FIG. 63 shows the zoom lens system with the zoom groups positioned at the longest focal length and the focus group focused at infinity. Similarly, the ray aberration graphs of FIG. 64 are at infinity focus and maximum focal length. It should be noted that the use of a binary surface in this embodiment is a modification that may be used in any of the embodiments of the invention disclosed herein or future variations of the invention.
FIGS. 65 and 66 illustrate an example of another embodiment of the present invention. This embodiment of the zoom lens system of the present invention is very similar to the embodiment of FIGS. 10-62, except that a binary (diffractive) surface is provided. Specifically, the binary surface is provided on the front surface (surface No. 6 in the prescription) of the third lens element from the left. As described above with respect to FIGS. 10-62, that third lens element is the first (front) of two lens elements comprising the second focus group FG2, which is movable axially for accomplishing the focusing together with the movable first focus group FG1 comprised of only the second lens element. The lens system optical prescription for the embodiment of FIGS. 65 and 66 is set forth below in the tables generally entitled “Tables for FIGS. 65 and 66.”










TABLES FOR FIGS. 65 and 66


LENS SYSTEM OPTICAL PRESCRIPTION























Glass



Surface
Radius
Thickness
Name







OBJECT
Infinity
Variable




S1
Infinity
50.000



S2
−617.930
5.200
S-LAM60



S3
425.207
Variable



S4
−2291.780
4.900
S-TIH6



S5
545.459
Variable



S6#
961.467
19.482
BK7



S7
−607.161
0.730



S8
1355.262
12.601
BK7



S9
−1118.653
Variable



S10
986.310
20.386
S-FPL51



S11
−502.874
0.730



S12
343.826
21.232
S-FPL51



S13
64586.450
0.730



S14
181.736
24.150
S-FPL53



S15
476.848
Variable



S16
208.678
3.120
S-LAH66



S17*
40.147
6.111



S18
67.136
3.150
S-LAH59



S19
56.870
14.527



S20
−98.690
2.730
S-LAH66



S21
90.992
12.506
S-TIH53



S22
−174.619
Variable



S23
764.771
14.926
S-FPL52



S24
−66.842
0.400



S25
133.738
17.704
S-FPL51



S26
−69.988
3.100
S-LAM66



S27
−1580.221
0.400



S28
65.214
9.613
S-NSL36



S29
129.561
Variable



STOP
Infinity
8.811



S31*
−36.392
2.044
S-BSM14



S32
−425.016
6.131



S33
−43.308
5.233
S-TIH53



S34
−33.861
0.200



S35
47.203
13.980
S-FPL51



S36
−41.565
2.400
S-LAM66



S37
−56.845
0.200



S38
−109.533
1.950
S-LAH63



S39
31.532
10.159
S-FPL51



S40
−173.403
45.721



S41
47.891
4.513
S-LAH53



S42
−2514.287
41.843



S43
−23.807
9.483
S-LAH59



S44
−24.610
12.719



S45
61.223
3.114
S-FPL51



S46
−45.071
0.150



S47
24.918
3.242
S-BSM9



S48
−516.606
Variable



S49
−72.073
1.059
S-LAL54



S50
23.513
2.783



S51
−18.951
0.900
S-LAH59



S52
−57.174
1.347



S53
−21.150
21.292
S-LAH60



S54
−31.181
Variable



S55
−138.459
4.401
S-BAL22



S56
−75.648
0.300



S57
606.713
5.842
S-FPL51



S58
−96.488
0.300



559
113.288
7.382
S-FPL51



560
−97.742
2.500
S-TIH6



S61
−366.723
0.300



S62
400.000
0.000



S63
38.760
8.585
S-FPL52



S64
269.438
5.901



S65
115.000
0.450



S66
94.072
1.770
S-LAL54



S67
35.982
7.000



S68
−90.502
2.010
S-LAL8



S69
29.972
6.150
S-TIH53



S70
82.308
2.725



S71
79.000
9.670



S72
76.232
6.100
S-PHM52



S73
−75.003
0.761



S74
45.420
7.170
S-FSL5



S75
−45.317
1.500
S-TIH53



S76
348.342
18.544



S77
Infinity
13.200
S-BSL7



S78
Infinity
2.000



S79
Infinity
33.000
BAF52



S80
Infinity
0.000



S81
Infinity
0.000



IMAGE
Infinity











Note: Maximum image diameter = 11.3 mm


*Surface profiles of aspheric surfaces S17 and S31 are governed by the


following conventional equation:






  Z
  =
  
    
      
        
          (
          CURV
          )
        
        ⁢
        
          Y
          2
        
      
      
        1
        +
        
          
            (
            
              1
              -
              
                
                  (
                  
                    1
                    +
                    K
                  
                  )
                
                ⁢
                
                  
                    (
                    CURV
                    )
                  
                  2
                
                ⁢
                
                  Y
                  2
                
              
            
            )
          
          
            1
            /
            2
          
        
      
    
    +
    
      
        (
        A
        )
      
      ⁢
      
        Y
        4
      
    
    +
    
      
        B
        ⁡
        
          (
          Y
          )
        
      
      6
    
    +
    
      
        (
        C
        )
      
      ⁢
      
        Y
        8
      
    
    +
    
      
        (
        D
        )
      
      ⁢
      
        Y
        10
      
    
  






where: CURV = 1/(Radius of Surface)


Y = Aperture height, measured perpendicular to optical axis


K, A, B, C, D = Coefficients


Z = Position of surface profile for a given Y value, as


measured along the optical axis from the pole


(i.e. axial vertex) of the surface.












The coefficients for

The coefficients for




the surface S17 are:

the surface S31 are:
















K =
−0.3564029
K =
0.4304792



A =
−8.6827410e−007
A =
9.5769727e−007



B =
−2.1510889e−010
B =
1.3131850e−009



C =
−6.3664850e−014
C =
−1.4559220e−012



D =
−3.8937870e−018
D =
3.1953640e−015











#Surface profile of binary surface S6 is governed by the


following conventional equation:


Added Phase =A1p2 + A2p4 + A3p6 + A4p8 + A5p10


where:


A1, A2, A3, A4 and A5 are coefficients and p is the


normalized radial coordinate at the surface.


The normalizing factor is set at unity and the p's become simply radial


coordinates.


A1 = −0.038094023


A2 = −2.7327913e−006


A3 = 5.0795942e−010


A4 = −5.0245151e−014


A5 = 1.5103625e−018









VARIABLE THICKNESS POSITIONS AND DATA















P1
P2
P3
P4
P5
P6
P7


















EFL
7.428
12.285
19.009
32.781
65.564
93.100
144.823


F/No.
1.949
1.949
1.949
1.949
1.949
2.010
2.090


S0
Infinity
5322.630
2499.896
Infinity
5322.630
Infinity
5322.630


S3
18.151
48.521
79.959
18.151
48.521
18.151
48.521


S5
6.399
10.135
15.000
6.399
10.135
6.399
10.135


S9
71.409
37.303
1.000
71.409
37.303
71.409
37.303


S15
1.350
67.051
110.745
155.094
189.151
203.856
210.392


S22
319.660
247.857
197.854
142.790
92.653
65.474
50.046


S29
9.625
15.727
22.036
32.751
48.830
61.304
70.197


S48
1.498
1.498
1.498
1.498
1.498
2.823
4.711


S54
63.257
63.257
63.257
63.257
63.257
61.933
60.044












VARIABLE THICKNESS POSITIONS AND DATA














P8
P9
P10
P11
P12
P13

















EFL
206.030
486.383
715.335
2050.042
4776.501
1890.393


F/No.
2.360
2.840
5.600
14.500
14.500
5.600


S0
Infinity
5322.630
Infinity
Infinity
8708.002
5322.630


S3
18.151
48.521
18.151
18.151
37.472
48.521


S5
6.399
10.135
6.399
6.399
8.770
10.135


S9
71.409
37.303
71.409
71.409
49.718
37.303


S15
215.814
218.878
223.339
224.980
224.980
223.339


S22
33.074
24.338
10.235
1.719
1.719
10.235


S29
81.746
87.419
97.063
103.934
103.934
97.063


S48
9.572
14.559
31.080
63.536
63.536
31.080


S54
55.183
50.196
33.675
1.220
1.220
33.675









The prescription of binary surface 6 is included following the lens system optical prescription table listed above. The addition of binary surface 6 to the basic lens system optical prescription of the embodiment of FIGS. 10-62 allows the substitution of less expensive glass, such as BK7, for the fluor-crown glass of lens elements 3 and 4 (third and fourth from the left in FIG. 65). Although other small changes are also made in the prescription, the zoom lens system of FIGS. 65 and 66 has the same number of lens elements and the same number of moving groups for focusing and zoom as the embodiment of FIGS. 10-62. FIG. 65 shows the zoom lens system with the zoom groups positioned at the longest focal length and the focus groups focused at infinity. Similarly, the ray aberration graphs of FIG. 66 are at infinity focus and the longest focal length.
FIGS. 67-70 illustrate an example of another embodiment of the present invention. This embodiment of the zoom lens system of the present invention has a zoom ratio of about 400:1. Specifically, this embodiment has a zoom range of focal lengths of about 7.47 mm (the position shown in FIG. 67) to about 2983 mm (the position shown in FIG. 68). As with the embodiment of FIGS. 10-62, this embodiment has three moving zoom lens groups ZG1, ZG2 and ZG3, with two of them in the front zoom lens portion and one in the rear zoom lens portion. The ray aberration graphs of FIGS. 69 and 70 are at paraxial effective focal lengths (EFL) of 7.47 mm and 2983 mm, respectively, and illustrate that this embodiment performs well, considering the extremely wide range of focal lengths and large zoom ratio which is similar to the performance characteristics of the embodiment of FIGS. 10-62. The optical diagrams of FIGS. 67 and 68 and the ray aberration graphs of FIGS. 69 and 70 are shown at infinity focus.
The lens system optical prescription of FIGS. 67-70 is set forth below in the tables generally entitled “Tables for FIGS. 67 thru 70.” The following data in the lens system optical prescription is set forth in the same manner and the legends have the same meanings as in the preceding lens system optical prescriptions.










TABLES FOR FIGS. 67 thru 70


LENS SYSTEM OPTICAL PRESCRIPTION























Glass



Surface
Radius
Thickness
Name







OBJECT
Infinity
Variable



S1
1018.780
15.000
LAH78



S2
277.432
28.775



S3
523.118
37.500
S-FPL51



S4
−634.022
1.500



S5
323.390
30.000
S-FPL51



S6#
−2096.922
−0.001



S7*
177.503
27.000
S-FPL51



S8
667.737
Variable



S9
363.133
6.000
TAF1



S10*
84.560
23.084



S11
−1731.870
4.500
TAF1



S12
117.736
21.933



S13
−68.241
4.672
TAF1



S14
1396.861
11.280
PBH71



S15
−123.171
Variable



S16
−351.922
21.562
S-FPL51



S17
−87.960
0.750



S18
670.190
25.507
LAK21



S19
−96.809
4.500
FD6



S20
−253.794
18.318



S21
112.307
6.052
FCS



S22
345.143
Variable



STOP
Infinity
6.066



S24*
−49.612
4.500
PSK53A



S25
45.951
6.491
FD15



S26
149.306
8.138



S27
−53.675
2.556
PSK53A



S28
−436.714
15.264
FD8



S29
−53.001
30.067



S30
96.369
40.439
S-FPL51



S31
−47.937
4.500
S-LAH75



S32
−65.887
0.018



S33
314.723
4.500
S-LAH75



S34
44.980
33.625
S-FPL53



S35
−197.211
62.647



S36*
59.624
15.000
S-FPL53



S37
−45862.250
62.567



S38
Infinity
2.000



S39
−250.000
2.000
S-LAH66



S40
38.600
21.997



S41
−42.668
3.012
PBH23W



S42
78.619
20.849
S-LAL8



S43
−54.572
0.250



S44
701.714
11.340
S-LAL8



S45
−96.232
0.250



S46
153.694
14.173
S-LAL8



S47
−120.652
0.250



S48
57.764
24.753
S-LAM2



S49
−654.450
3.706
P8H6W



S50
36.175
17.533



S51
126.517
2.500
PBH53W



S52
123.911
5.000
S-BSM14



S53
−269.378
0.200



S54
119.317
5.000
S-BSM18



S55
249.395
Variable



S56
77.473
2.500
S-LAH60



S57
24.795
8.736



S58
−17.880
2.000
S-LAH55



S59
−73.667
1.561



S60
−68.965
7.000
PBH53W



S61
−23.620
0.200



S62
−39.257
2.000
S-LAH65



S63
−73.267
Variable



S64*
40.900
24.089
S-BAL42



S65*
−82.736
0.200



S66
68.814
3.000
PBH53W



S67
33.834
Variable



S68
47.963
12.055
S-BSL7



S69
−38.097
8.000
PBH6W



S70
−61.203
Variable



S71
Infinity
11.874
S-BSL7



S72
Infinity
14.000



IMAGE
Infinity











Note: Maximum image diameter = 11.0 mm


*Surface profiles of aspheric surfaces S7, S10, S24, S36, S64 and


S65 are governed by the following conventional equation






  
    
      
        
          Z
          =
          
          ⁢
          
            
              
                
                  (
                  CURV
                  )
                
                ⁢
                
                  Y
                  2
                
              
              
                1
                +
                
                  
                    (
                    
                      1
                      -
                      
                        
                          (
                          
                            1
                            +
                            K
                          
                          )
                        
                        ⁢
                        
                          
                            (
                            CURV
                            )
                          
                          2
                        
                        ⁢
                        
                          Y
                          2
                        
                      
                    
                    )
                  
                  
                    1
                    /
                    2
                  
                
              
            
            +
            
              
                (
                A
                )
              
              ⁢
              
                Y
                4
              
            
            +
            
              
                B
                ⁡
                
                  (
                  Y
                  )
                
              
              6
            
            +
            
              
                (
                C
                )
              
              ⁢
              
                Y
                8
              
            
            +
            
              
                (
                D
                )
              
              ⁢
              
                Y
                10
              
            
            +
          
        
      
    
    
      
        
          
          ⁢
          
            
              (
              E
              )
            
            ⁢
            
              Y
              12
            
          
        
      
    
  
   






where: CURV = 1/(Radius of Surface)


Y = Aperture height, measured perpendicular to optical axis


K, A, B, C, D, E = Coefficients


Z = Position of surface profile for a given Y value, as measured


along the optical axis from the pole


(i.e. axial vertex) of the surface.












The coefficients for

The coefficients for




the surface S7 are:

the surface S10 are:
















K =
−0.01834396
K =
0.1385814



A =
4.6192051e−009
A =
−6.1078514e−008



B =
2.9277175e−013
B =
−1.7110958e−012



C =
−5.3760139e−018
C =
−1.4298682e−015



D =
4.4429222e−022
D =
−7.3308393e−019



E =
0
E =
0
















The coefficients for

The coefficients for




the surface S24 are:

the surface S36 are:
















K =
−0.1283323
K =
0.009973727



A =
−2.7157663e−007
A =
3.3999271e−008



B =
1.4568941e−010
B =
1.4717268e−010



C =
−1.4055959e−012
C =
−1.0665963e−013



D =
9.7130719e−016
D =
6.8463872e−017



E =
0
E =
0
















The coefficients for

The coefficients for




the surface S7 are:

the surface S10 are:
















K =
−4.594951
K =
−0.2743554



A =
5.9382510e−006
A =
1.2036084e−006



B =
−4.3333569e−009
B =
3.8383867e−009



C =
−2.6412286e−013
C =
−1.5101902e−011



D =
5.0607811e−015
D =
2.3291313e−014



E =
−3.8443669e−018
E =
−1.3549754e−017











#Surface profile of binary surface S6 is governed by the


following conventional equation:


Added Phase = A1p2 + A2p4 + A3p6 + A4p8 + A5p10 + A6p12


where: A1, A2, A3, A4, A5 and A6 are coefficients and p is


the normalized radial coordinate at the surface.


The normalizing factor is set at unity and the p's become simply radial


coordinates.


A1 = −0.0183497


A2 = 0.1385814


A3 = −0.1283323


A4 = 0.0099737


A5 = −4.5949510


A6 = −0.2743554









VARIABLE THICKNESS POSITIONS AND DATA















P1
P2
P3
P4
P5
P6
P7


















EFL
7.471
11.746
18.475
29.059
45.676
649.701
2981.989


F/No.
1.600
1.600
1.600
1.600
1.600
6.000
18.000


S0
Infinity
Infinity
Infinity
Infinity
Infinity
Infinity
Infinity


S8
3.884
47.335
81.309
107.642
127.477
147.901
156.198


S15
243.496
190.547
145.303
105.453
68.586
39.080
0.104


S22
5.292
14.777
26.064
39.600
56.513
65.772
96.339


S55
1.000
1.000
1.000
1.000
1.000
98.702
111.239


S63
117.540
117.540
117.540
117.540
117.540
30.129
0.368


S67
42.175
42.175
42.175
42.175
42.175
20.670
63.421


S70
14.512
14.512
14.512
14.512
14.512
25.727
0.199









Detailed Description of Folded Lens Embodiment
FIG. 71 is an optical diagram illustrating an example of still another embodiment of the present invention incorporating one or more mirrors for folding the lens for added compactness. The example of FIG. 71 is similar to the previously-described embodiments, with three general zoom groups identified as 50, 52 and 54. An intermediate image is located at 56. The focus group 66 is movable during focusing, but is stationary when the lens is at a constant focus. The aperture stop is located at 84. Unique to the folded zoom lens embodiment of FIG. 71 is a mirror 64 located between the front and rear zoom groups 52 and 54 for “folding” or bending the radiation rays. The embodiment of FIG. 71 may be employed in any camera, but is particularly suited for small cameras such as point-and-shoot handheld cameras because the folded design enables the lens to fit into a smaller space. FIG. 71 illustrates an SLR embodiment containing a reflex mirror 60 and an eyelens 62 for enabling a user to see the image while the reflex mirror 60 is in the position indicated in FIG. 71.
Embodiments of the present invention are particularly suited to folding because mirror 64 may be placed within the intermediate image space 58 in any area that does not interfere with the movement of the zoom groups 52 and 54. In contrast, conventional compact zoom lenses have lens elements that must retract into the body of the camera, which eliminates most or all or the air gaps within the lens and precludes the insertion of a mirror. In the example of FIG. 71, the mirror 64 is located on the image side of the intermediate image 56. However, in other embodiments, the mirror 64 may be located on the object side of the intermediate image 56. It should be understood that other embodiments of the present invention may have multiple folds (mirrors), and that the mirrors need hot be oriented at 45 degrees with respect to the optical axis.
The folded lens illustrated in the example of FIG. 71 enables several useful design possibilities and advantages. As mentioned above, the fold in the lens enables the zoom lens to take up less space. Furthermore, the folded zoom lens enables some or all of the lens elements to reside within the body of the camera, further improving compactness. In one embodiment, even the focus lens group 66 may reside entirely within the body of the camera, protecting the lens and making the camera even more compact. In addition, the folded zoom lens enables compact cameras to achieve a zoom ratio of about 10:1 or higher, compared to a maximum of about 4:1 in conventional compact cameras. Moreover, conventional SLR cameras require a bulky pentaprism for flipping the image, and thus compact cameras typically avoid through-the-lens viewing. However, because of the intermediate image 56 and mirrors 64 and 60 in the present invention, the final image is already properly oriented without the need for a bulky pentaprism, and through-the-lens viewing is made possible even in cameras of a compact size.
The exemplary folded zoom lens of FIG. 71 provides an EFL of about 12 mm to 120 mm, a zoom ratio of about 10:1, an “f” number range of about f/3 to f/5 at full aperture and a maximum field of view angle in object space of about 84.1 degrees to 10.3 degrees, and receives radiation within a waveband of at least 486 nm to 588 nm. The image generated by the embodiment of FIG. 71 is about 12 mm in height by about 18 mm in width with a diagonal dimension of about 21.65 mm, which is about half the size of the image in a conventional 35 mm still photography camera.
FIGS. 72A-72D are optical diagrams illustrating the folded zoom lens example embodiment of FIG. 71 at other zoom positions, with the folded lens shown in a flat (unfolded) orientation for clarity and the zoom groups in various exemplary positions. As in FIG. 71, the focus lens group 66 in the example of FIGS. 72A-72D is movable for focusing and stationary at a constant focus, and the mirror 64 and eyelens 62 are also stationary. The aperture stop is located at 84 and is movable during zooming. The zoom lens example of FIGS. 72A-72D is actually comprised of eight moving zoom groups 68, 70, 72, 74, 76, 78, 80 and 82, although it should be understood that other embodiments of the folded zoom lens may include more or fewer zoom groups. The folded zoom lens example of FIGS. 72A-72D utilizes all spherical surfaces, but it should be understood that other embodiments may employ aspheres and/or binary (diffractive) surfaces.
Detailed Description of Infrared Embodiment
FIGS. 73A-73C are optical diagrams for an example of an infrared (IR) embodiment of the zoom lens system of the present invention, illustrating various positions of the zoom groups. The intermediate image is located at 86. The focus group 88 is movable during focusing, but is stationary at a constant focus. The final image plane is located at 90, and the aperture stop is located at 92. The embodiment of FIGS. 73A-73C may be employed in low light and surveillance cameras because the zoom lens system is designed for infrared wavelengths. The example of FIGS. 73A-73C provides an EFL of 6.68 mm to 1201.2 mm, an “f” number range of f/2.00 to f/5.84, an image diagonal of 8.0 mm, a maximum field of view angle in object space of 64.5 degrees to 0.388 degrees, and a vertex length of 902.28 mm. There is a −4.93% distortion at the 6.68 mm focal length position and +0.34% distortion at the 1201.2 mm focal length position. This distortion increases the effective zoom ratio to 190:1. There are a total of nine elements in the example of FIGS. 73A-73C, with six elements (94, 96, 98, 100, 102 and 104) in the zoom kernel 106, and three elements (108, 110 and 112) in the zoom relay 114. Note that the “zoom kernel,” as referred to herein, represents all of the elements from object space to the intermediate image, while the “zoom relay,” as referred to herein, represents all of the elements from the intermediate image to the final image.
The lens system optical prescription for the IR embodiment of FIGS. 73A-73C is set forth below in the tables generally entitled “Tables for FIGS. 73A, 73B and 73C.” The following data in the lens system optical prescription is set forth in the same manner and the legends have the same meanings as in the preceding lens system optical prescriptions.










TABLES FOR FIGS. 73A, 73B and 73C


LENS SYSTEM OPTICAL PRESCRIPTION























Refractive



Surface
Radius
Thickness
Material







OBJECT
Infinity
Infinity



S1
Infinity
25.000



S2*
341.091
15.000
GERMANIUM



S3#
442.256
14.496



S4
628.089
15.000
ZNSE



S5
817.176
Variable



S6*
191.321
5.000
GERMANIUM



S7
101.374
Variable



S8
−108.986
5.000
GERMANIUM



S9
−133.542
Variable



S10*
132.195
10.000
GERMANIUM



S11
215.451
106.451



S12*
44.406
7.000
GERMANIUM



S13*
47.364
Variable



S14*
−146.583
5.000
GERMANIUM



S15*
−103.306
Variable



S16*
−48.015
6.000
ZNSE



S17*
−54.690
Variable



S18*
−134.510
5.000
GERMANIUM



S19*
−96.541
Variable



STOP
Infinity
74.251



IMAGE
Infinity











Note: Maximum image diameter = 8.0 mm


*Surface profiles of aspheric surfaces S2, S6, S10, S12, S13,


S14, S15, S16, S17, S18 and S19


are governed by the following conventional equation:


 






  
    
      
        
          Z
          =
          
          ⁢
          
            
              
                
                  (
                  CURV
                  )
                
                ⁢
                
                  Y
                  2
                
              
              
                1
                +
                
                  
                    (
                    
                      1
                      -
                      
                        
                          (
                          
                            1
                            +
                            K
                          
                          )
                        
                        ⁢
                        
                          
                            (
                            CURV
                            )
                          
                          2
                        
                        ⁢
                        
                          Y
                          2
                        
                      
                    
                    )
                  
                  
                    1
                    /
                    2
                  
                
              
            
            +
            
              
                (
                A
                )
              
              ⁢
              
                Y
                4
              
            
            +
            
              
                B
                ⁡
                
                  (
                  Y
                  )
                
              
              6
            
            +
            
              
                (
                C
                )
              
              ⁢
              
                Y
                8
              
            
            +
          
        
      
    
    
      
        
          
          ⁢
          
            
              
                (
                D
                )
              
              ⁢
              
                Y
                10
              
            
            +
            
              
                (
                E
                )
              
              ⁢
              
                Y
                12
              
            
            +
            
              
                (
                F
                )
              
              ⁢
              
                Y
                14
              
            
            +
            
              
                (
                G
                )
              
              ⁢
              
                Y
                16
              
            
          
        
      
    
  
   






 


where:


CURV = 1/(Radius of Surface)


Y = Aperture height, measured perpendicular to optical axis


A, B, C, D, E, F, G = Coefficients


Z = Position of surface profile for a given V value, as


measured along the optical axis from the pole


(i.e. axial vertex) of the surface.












The coefficients for the

The coefficients for the




surface S2 are:

surface S6 are:
















K =
−0.3170663
K =
0.0000000



A =
7.1675212e−010
A =
8.8834511e−009



B =
4.6490286e−015
B =
−1.1017434e−012



C =
3.1509558e−020
C =
4.2407818e−016



D =
−3.0230207e−026
D =
−4.5843672e−020



E =
1.8711604e−043
E =
0



F =
7.2023035e−034
F =
0



G =
−1.6899714e−038
G =
0
















The coefficients for the

The coefficients for the




surface S10 are:

surface S12 are:
















K =
0.0000000
K =
0.1424633



A =
−4.1468720e−008
A =
−1.3741884e−008



B =
−1.1864804e−012
B =
2.0574529e−010



C =
1.0375271e−016
C =
2.2356569e−013



D =
1.4819552e−020
D =
−9.2592205e−016



E =
0
E =
0



F =
0
F =
0



G =
0
G =
0
















The coefficients for the

The coefficients for the




surface S13 are:

surface S14 are:
















K =
0.1341907
K =
0.0000000



A =
2.5853953e−007
A =
−2.3627230e−006



B =
6.3040925e−010
B =
−3.2069853e−009



C =
−8.9182471e−013
C =
1.9995538e−012



D =
−2.1087914e−016
D =
−4.1873811e−015



E =
0
E =
−4.5598387e−018



F =
0
F =
1.5355757e−021



G =
0
G =
2.7742963e−025
















The coefficients for the

The coefficients for the




surface S15 are:

surface S16 are:
















K =
0.0000000
K =
0.0000000



A =
−1.9992749e−006
A =
−5.5264489e−007



B =
−2.7451965e−009
B =
−3.4855834e−011



C =
2.5915567e−012
C =
−1.5605019e−013



D =
−5.4747396e−015
D =
8.4346229e−016



E =
1.0432409e−018
E =
−2.6930213e−019



F =
−9.7041838e−023
F =
7.0886850e−022



G =
3.5844261e−025
G =
−4.8763355e−025
















The coefficients for the

The coefficients for the




surface S17 are:

surface S18 are:
















K =
0.0000000
K =
0.0000000



A =
−1.9256081e−007
A =
4.5197079e−007



B =
9.7560057e−012
B =
−4.7688707e−010



C =
−3.1406997e−013
C =
−2.2771179e−013



D =
−4.6996712e−016
D =
−7.3812375e−016



E =
4.3471337e−019
E =
6.1621050e−019



F =
−3.7957715e−022
F =
−2.9782920e−023



G =
−2.4875152e−026
G =
−2.8295343e−026














The coefficients for




the surface S19 are:















K =
0.0000000



A =
3.9066750e−007



B =
−2.6768710e−010



C =
−3.7378469e−013



D =
−4.0450877e−016



E =
3.9230103e−019



F =
−3.7514135e−023



G =
−8.0738327e−027











#Surface profile of binary surface S3 is governed by the


following conventional equation:


Added Phase = A1p2 + A2p4 + A3p6 + A4p8 + A5p10


where:


A1, A2, A3, A4 and A5 are coefficients and p is


the normalized radial coordinate at the surface.


The normalizing factor is set at unity and the p's become simply


radial coordinates.


A1 = −0.0085882326


A2 = −1.2587653e−008


A3 = −5.4668365e−013


A4 = 8.4183658e−018


A5 = 1.3774055e−022









VARIABLE THICKNESS POSITIONS AND DATA














P1
P2
P3
P4
P5
P6





EFL
6.677
7.583
9.331
11.805
14.069
23.805


F/No.
2.000
2.000
2.000
2.000
2.000
2.000


S5
5.000
25.000
55.000
85.000
105.000
155.000


S7
239.848
216.543
180.384
143.845
119.259
58.715


S9
72.916
76.220
82.379
88.919
93.504
104.048


S13
276.674
276.674
276.674
276.674
276.674
276.674


S15
5.030
5.030
5.030
5.030
5.030
5.030


S17
29.517
29.517
29.517
29.517
29.517
29.517


S19
5.000
5.000
5.000
5.000
5.000
5.000












VARIABLE THICKNESS POSITIONS AND DATA














P7
P8
P9
P10
P11
P12





EFL
48.419
84.275
133.455
175.637
231.172
304.215


F/No.
2.000
2.000
2.000
2.300
2.900
3.400


S5
205.000
231.305
243.545
243.545
243.545
243.545


S7
16.543
30.757
72.218
72.218
72.218
72.218


S9
96.221
55.701
2.000
2.000
2.000
2.000


S13
276.674
276.674
276.674
248.444
220.313
187.659


S15
5.030
5.030
5.030
42.180
79.972
109.931


S17
29.517
29.517
29.517
22.953
12.626
5.000


S19
5.000
5.000
5.000
2.644
3.310
13.631












VARIABLE THICKNESS POSITIONS AND DATA













P13
P14
P15
P16
P17





EFL
400.368
526.915
693.449
912.675
1201.182


F/No.
3.500
3.800
4.600
5.300
5.840


S5
243.545
243.545
243.545
243.545
243.545


S7
72.218
72.218
72.218
72.218
72.218


S9
2.000
2.000
2.000
2.000
2.000


S13
146.432
112.380
97.552
94.304
95.940


S15
114.831
95.642
67.311
40.305
16.014


S17
10.137
19.763
26.212
25.615
18.454


S19
44.821
88.436
125.146
155.997
185.814









FIGS. 74-76 are ray aberration graphs corresponding to the position of the zoom groups shown in FIGS. 73A-73C, respectively. The ray aberration graphs of FIGS. 74-76 are at paraxial effective focal lengths (EFL) of 6.68 mm, 133.46 mm, and 1201.18 mm, respectively, and a wavelength range of 8-12 microns. The optical diagrams of FIGS. 73A-73C and the ray aberration graphs of FIGS. 74-76 are shown at infinity focus.
Detailed Description of 3-5 Micron Infrared Embodiment
FIG. 77 illustrates an unfolded layout of a second exemplary IR embodiment of the zoom lens system with lens elements and surfaces identified. Referring to FIG. 77, each lens element is identified by a numeral from 120 through 138 (by twos) and the general configuration of each lens element is depicted, but the actual radius of each lens surface is set forth below in the table entitled “TABLE FOR FIGS. 77 AND 78A-78F.” The lens surfaces are identified by the letter “S” followed by a numeral from S0 through S23. The optical axis is identified by the symbol “Ø”. Each lens element has its opposite surfaces identified by a separate but consecutive surface number as, for example, lens element 120 has lens surfaces S1 and S2, lens element 126 has lens surfaces S7 and S8 and so forth. The intermediate image is located between S10 and S12. An optical stop is located at S22. The real image surface is identified by the numeral S23. All of the lens surfaces are spherical except lens surfaces S2, S8, S9 and S21 which are aspheric surfaces that are non-spherical, non-plano but rotationally symmetrical about the optical axis.
There are a total of 10 elements in the example of FIG. 77, with five elements (120, 122, 124, 126 and 128) in the zoom kernel or first lens group 151, and five elements (130, 132, 134, 136 and 138) in the zoom relay or second lens group 156. The optical design of the second exemplary IR embodiment can be characterized as an NPP kernel followed by an NNP relay. Note that the “zoom kernel,” as referred to herein, represents all of the elements from object space to the intermediate image, while the “zoom relay,” as referred to herein, represents all of the elements from the intermediate image to the final image.
The light rays entering the zoom lens system at the left are comprised of exemplary axial field beams 160 and exemplary off-axis field beams 162, 164 and 166, with the outer light rays in each field beam referred to as rim rays and the inner light ray in each field beam referred to as a chief or principal light ray. The off-axis field beam whose rim ray is furthest from the optical axis is referred to as the off-axis field beam maximum rim ray. Note that the off-axis field beam chief ray first crosses the optical axis before the intermediate image, and later crosses the optical axis again at the optical stop.
Before describing the detailed characteristics of the lens elements, a broad description of the lens groups and their axial positions and movement will be given for the zoom lens system, generally designated 150, of this second exemplary embodiment of the present invention. Beginning from the end facing the object to be photographed, i.e. the left end in FIG. 77, the first lens group 151 comprises a first lens subgroup 152, a first zoom subgroup 153, a second zoom subgroup 154, and a third zoom subgroup 155. The first lens subgroup 152 is a positive-powered subgroup and comprises singlet lens element 120 which gathers light from object space. The first lens subgroup 152 is movable during focusing, but is stationary and at a fixed distance with respect to the image plane S23 at a constant focus. The first zoom subgroup 153 is a negative-powered subgroup and comprises singlet lens elements 122 and 124. The second zoom subgroup 154 is a positive-powered subgroup and comprises a singlet lens element 126. The third zoom subgroup 155 is a positive-powered subgroup and comprises a singlet lens element 128. A second lens group 156 comprises a fourth zoom subgroup 157, a fifth zoom subgroup 0.158, and a sixth zoom subgroup 159. The fourth zoom subgroup 157 is a negative-powered subgroup and comprises a singlet lens element 130. The fifth zoom subgroup 158 is a negative-powered subgroup and comprises a singlet lens element 132. The sixth zoom subgroup 159 is a positive-powered subgroup and comprises singlet lens elements 134, 136 and 138, and includes an optical stop at S22. Although element 138 in the sixth zoom subgroup is rather thin in the example provided, in alternative embodiments this element may be thickened to improve its manufacturability. An axially movable intermediate image is located between the third zoom subgroup 155 and the fourth zoom subgroup 157. The second exemplary IR embodiment of the zoom lens system is set forth below in the table entitled “TABLE FOR FIGS. 77 AND 78A-78F.”
There are six independently moving groups altogether, three on the object side and three on the image side of the intermediate image. The horizontal arrows with arrowheads on both ends in the upper portion of FIG. 77 indicate that each of the zoom subgroups 153-159 are movable in both axial directions along the optical axis, some in a monotonic manner (i.e. in only one direction when progressing from one extreme to the other of adjustments) and others in a non-monotonic manner. While only the lens elements are physically shown in FIG. 77, it is to be understood that conventional mechanical devices and mechanisms are provided for supporting the lens elements and for causing axial movement of the movable groups in a conventional lens housing or barrel.
Note that the space between lens elements as shown in FIG. 77 and FIGS. 78A-78F suggests that a fold mirror could be located between zoom subgroups 154 and 155 and/or between the optical stop at S22 and the final image at S23 to create a folded embodiment.
The embodiment of FIG. 77 may be employed in low light and surveillance cameras because the zoom lens system is designed for IR wavelengths. The example of FIG. 77 provides an EFL of about 11.8 mm to 1137.1 mm, an “f” number range of about f/2.80 to f/4.00, an image diagonal of about 18.0 mm, a maximum field of view angle in object space of about 0.45 degrees to 37.36 degrees, and a vertex length from the front vertex (i.e. surface S1) to the final image (i.e. surface S22) of about 945 mm. There is a 1.55% distortion at the 11.8 mm focal length position and 2.14% distortion at the 1137.1 mm focal length position. This distortion increases the effective zoom ratio to approach about 100:1.
FIGS. 78A-78F are optical diagrams for the second exemplary IR embodiment of the zoom lens system, illustrating various positions of the zoom groups. It should be noted that lens elements 120 and 122 (the leftmost two elements) in FIG. 78A, although apparently touching, are in fact separated by a gap. Note also that in FIG. 78F, all rim rays for both the axial field beam and the off-axis field beams are roughly superimposed on each other, which enables the front lens element 120 to be made smaller and cheaper. In particular, the off-axis field beam maximum rim ray height (distance from rim ray to optical axis) is about 158.82 mm, and the axial field beam rim ray height is about 149.53 mm. The ratio of the off-axis field beam maximum rim ray distance to the axial field beam rim ray distance is about 1.062, which indicates that the first lens subgroup elements had to be made larger than ideal by only about 6.2%. It should be understood that a ratio of less than 1.25 is generally acceptable. Ideally, the off-axis field beam maximum rim rays and the axial field beam rim rays would be exactly superimposed on each other, resulting in a ratio of 1.000 and optimal size and cost for at least the first lens group.
The lens system optical prescription and fabrication data for the second exemplary IR embodiment of FIGS. 77 and 78A-78F is set forth below in the table generally entitled “TABLE FOR FIGS. 77 AND 78A-78F.” In the TABLE FOR FIGS. 78A-78F, the first column “ITEM” identifies each optical element, with the same numeral or label as used in FIG. 77. The second and third columns identify the “Group” and “Subgroup,” respectively, to which that optical element (lens) belongs with the same numerals used in FIG. 77. The fourth column “Surface” is a list of the surface numbers, of the object S0, the Stop (iris) S22, the image plane S23 and each of the actual surfaces of the lenses, as identified in FIG. 77. The fifth column “Zoom Position” identifies six typical zoom positions (Z1-Z6) of the zoom subgroups 153-159 (illustrated in FIGS. 78A-78F) wherein there are changes in the distance (separation) between some of the surfaces listed in the fourth column, as described below more thoroughly. The sixth column, headed by the legend “Radius of Curvature,” is a list of the optical surface radius of curvature for each surface, with a minus sign (−) meaning the center of the radius of curvature is to the left of the surface, as viewed in FIG. 77, and “Infinity” meaning an optically flat surface. The asterisk (*) for surfaces S2, S8, S9 and S21 indicate these are aspheric surfaces for which the “radius of curvature” is a base radius, and the formula and coefficients for those two surfaces are set forth as a footnote to the TABLE FOR FIGS. 77 AND 78A-78F at the * (asterisk). The seventh column “Thickness or Separation” is the axial distance between that surface (fourth column) and the next surface. For example, the distance between surface S3 and surface S4 is 9.0 mm.
The eighth column of the TABLE FOR FIGS. 77 AND 78A-78F provide the refractive material of each lens element. The last column of the TABLE FOR FIGS. 77 AND 78A-78F headed “Aperture Diameter” provides the maximum diameter for each surface through which the light rays pass. All of the maximum aperture diameters, except for the Stop surface S22, are calculated assuming an image diagonal of 18 mm and a relative aperture ranging from f/2.8 at the shortest focal length to f/4.0 at the longest focal length. The maximum aperture diameters of the Stop surface S22 for Zoom Positions Z1-Z6 are 30.170 mm, 29.727 mm, 28.999 mm, 28.286 mm, 25.654 mm and 21.076 mm, respectively. The maximum relative apertures (f-number) for Zoom Positions Z1-Z6 are f/2.80, f/2.86, f/2.93, f/3.00, f/3.30 and f/4.00, respectively. Depending on the choice of the value of the maximum relative apertures for Zoom Positions Z1-Z6, then in one or more zoom positions a very small negative air gap may occur at the edges of certain elements between zoom subgroups. Those skilled in the art will realize that the small negative air gap can be removed from the system by routine optimization without changing the basic design.










TABLE FOR FIGS. 77 AND 78A-78F


OPTICAL PRESCRIPTION




























Radius of
Thickness or

Aperture




Sub-

Zoom
Curvature
Separation
Refractive
Diameter


Item
Group
Group
Surface
Position
(mm)
(mm)
Material
(mm)








S0 (Object)

Infinity
25.000


120
151
152
S1
All
215.343
28.544
Silicon
317.642





S2
Z1
269.106*
9.864

308.262






Z2

57.468






Z3

108.517






Z4

117.957






Z5

132.937






Z6

135.615


122
151
153
S3
All
637.888
9.000
Germanium
187.169





S4
All
247.226
11.642

174.123


124
151
153
S5
All
228.929
8.000
Silicon
166.617





S6
Z1
161.278
244.587

157.148






Z2

220.842






Z3

150.487






Z4

74.335






Z5

22.911






Z6

11.974


126
151
154
S7
All
288.682
15.448
Silicon
176.490





S8
Z1
1321.765*
212.856

174.473






Z2

233.828






Z3

270.854






Z4

362.883






Z5

443.606






Z6

460.309


128
151
155
S9
All
83.756*
11.053
Silicon
105.651





S10
Z1
159.357
160.888

103.666






Z2

115.791






Z3

97.933






Z4

72.886






Z5

28.278






Z6

20.171





S11 (dummy)
Z1
Infinity
74.210






Z2

46.803






Z3

3.191






Z4

3.253






Z5

57.219






Z6

19.714


130
156
157
S12
All
−32.997
12.500
Silicon
29.867





S13
Z1
−45.308
1.830

36.698






Z2

29.317






Z3

74.625






Z4

73.197






Z5

0.800






Z6

1.897


132
156
158
S14
All
−28.877
10.206
Germanium
23.882





S15
Z1
−44.286
1.917

30.694






Z2

0.995






Z3

0.100






Z4

0.926






Z5

4.846






Z6

18.907


134
156
159
S16
All
6208.244
13.998
Germanium
37.741





S17
All
264.338
0.400

40.076


136


S18
All
171.855
11.452
Silicon
41.269





S19
All
−84.226
0.400

42.354


138


S20
All
−128.685
1.000
Silicon
41.072





S21
Z1
−156.416*
1.254

41.075






Z2

1.696






Z3

0.750






Z4

1.699






Z5

15.734






Z6

38.441





S22 (Stop)
All
Infinity
79.221





S23 (Image)
All
Infinity
0.000










*Surface profiles of aspheric surfaces S2, S8, S9 and S21 are governed by the following conventional equation:






  
    
      
        
          Z
          =
          
          ⁢
          
            
              
                
                  (
                  CURV
                  )
                
                ⁢
                
                  Y
                  2
                
              
              
                1
                +
                
                  
                    (
                    
                      1
                      -
                      
                        
                          (
                          
                            1
                            +
                            K
                          
                          )
                        
                        ⁢
                        
                          
                            (
                            CURV
                            )
                          
                          2
                        
                        ⁢
                        
                          Y
                          2
                        
                      
                    
                    )
                  
                  
                    1
                    /
                    2
                  
                
              
            
            +
            
              
                (
                A
                )
              
              ⁢
              
                Y
                4
              
            
            +
            
              
                B
                ⁡
                
                  (
                  Y
                  )
                
              
              6
            
            +
            
              
                (
                C
                )
              
              ⁢
              
                Y
                8
              
            
            +
          
        
      
    
    
      
        
          
          ⁢
          
            
              
                (
                D
                )
              
              ⁢
              
                Y
                10
              
            
            +
            
              
                (
                E
                )
              
              ⁢
              
                Y
                12
              
            
            +
            
              
                (
                F
                )
              
              ⁢
              
                Y
                14
              
            
          
        
      
    
  
   






where:


CURV = 1/(Radius of Curvature)


Y = Aperture height, measured perpendicular to optical axis


K, A, B, C, D, E, F = Coefficients


Z = Position of surface profile for a given Y value, as measured along the optical


axis from the pole (i.e. axial vertex) of the surface.








The coefficients for the surface S2 of item 1 are:
The coefficients for the surface S9 of item 5 are:





K = −0.23909
K = −0.321348


A = −1.20061E−09
A = −1.84849E−07


B = 7.10421E−15
B = −3.24508E−11


C = −6.54538E−21
C = 4.30816E−14


D = 1.74055E−26
D = −2.13370E−18


E = 2.64213E−29
E = −7.80714E−21


F = −1.38143E−33
F = 1.67339E−24





The coefficients for the surface S8 of item 4 are:
The coefficients for the surface S21 of item 10 are:





K = 28.74452
K = 1.125040


A = 1.70772E−09
A = 8.42238E−07


B = 6.46357E−14
B = 2.42138E−11


C = −6.99028E−18
C = 4.68290E−13


D = 2.65455E−21
D = 1.19515E−15


E = −4.37148E−25
E = −2.58757E−18


F = 2.27757E−29
F = 3.72479E−21









The foregoing footnote * to the TABLE FOR FIGS. 77 AND 78A-78F includes the equation for calculating the shape of the aspheric surfaces S2, S8, S9 and S21 for the value Z, wherein CURV is the curvature at the pole of the surface, Y is the height or distance from the optical axis of a specific point on the surface of the glass, K is the conic coefficient, and A, B, C, D, E and F are the 4th, 6th, 8th, 10th, 12th and 14th, respectively, order deformation coefficients. As noted above, for illustrating the scope and versatility of the present invention there are six different Zoom Positions Z1-Z6 set forth in the data of the TABLE FOR FIGS. 77 AND 78A-78F which provide specific data for six different positions for the six movable zoom subgroups. The Zoom Positions Z1-Z6 are representative of six positions of the zoom subgroups 153-159 with Zoom Positions Z1 and Z6 being the extreme positions and Z2, Z3, Z4 and Z5 being intermediate positions. Of course, it will be understood that continuous zooming is available between the extreme Zoom Positions Z1 and Z6, and that any combination of continuous zooming is available within the described zoom ranges with the lens system 150. In addition, continuous focusing is available over the full range of axial motion of the first lens group 152.
The Effective Focal Length (EFL), Full Field Of View (FFOV) and F-number of the lens system 150 varies for the different Zoom Positions. Referring again to FIGS. 78A-78F, the zoom lens system 150 is shown with the zoom groups in various Zoom Positions and with light ray traces for those positions. FIG. 78A represents the zoom position Z1 for which data is set forth above in the TABLE FOR FIGS. 77 AND 78A-78F with an EFL of about 11.787 mm, a FFOV of about 74.72°, and an F-number of about 2.8. FIG. 78B represents the zoom position Z2 from the TABLE FOR FIGS. 77 AND 78A-78F with an EFL of about 22.999 mm, a FFOV of about 42.74°, and an F-number of about 2.9. FIG. 78C represents the zoom position Z3 from the TABLE FOR FIGS. 77 AND 78A-78F with an EFL of about 54.974 mm, a FFOV of about 18.6°, and an F-number of about 2.9. FIG. 78D represents the zoom position Z4 from the TABLE FOR FIGS. 77 AND 78A-78F with an EFL of about 125.359 mm, a FFOV of about 8.22°, and an F-number of about 3.0. FIG. 78E represents the zoom position Z5 from the TABLE FOR FIGS. 77 AND 78A-78F with an EFL of about 359.536 mm, a FFOV of about 2.86°, and an F-number of about 3.3. FIG. 78F represents the zoom position Z6 from the TABLE FOR FIGS. 77 AND 78A-78F with an EFL of about 1137.054 mm, a FFOV of about 0.9°, and an F-number of about 4.0.
From the specifications for the individual lens elements (items 120-138 by twos) and the separation between lens elements set forth in the TABLE FOR FIGS. 77 AND 78A-78F, the focal lengths of each lens element and then each group of lens elements (i.e. first lens group 152, first zoom subgroup 153, second zoom subgroup 154, third zoom subgroup 155, fourth zoom subgroup 157, fifth zoom subgroup 158, and sixth zoom subgroup 159) may be calculated by using CODE V® optical design software that is commercially available from Optical Research Associates, Inc., Pasadena, Calif., U.S.A., at a temperature of 20° C. (68° F.) and standard atmospheric pressure (760 mm Hg), and those calculated group focal lengths are as follows:

    
    
        First lens subgroup 152 (element 120)=322.994 mm;
        First zoom subgroup 153 (elements 122 and 124)=−88.338 mm;
        Second zoom subgroup 154 (element 126)=150.688 mm;
        Third zoom subgroup 155 (element 128)=65.962 mm; and
        Fourth zoom subgroup 157 (element 130)=−178.124 mm.
        Fifth zoom subgroup 158 (element 132)=−54.620 mm.
        Sixth zoom subgroup 159 (elements 134, 136 and 138)=35.153 mm.
    
    


As mentioned above, the zoom lens system 150 is provided with one optical stop at the surface S22 which controls the diameter of the aperture through which light rays may pass at that point to thereby cause any light rays in the zoom lens system radially beyond that diameter to be stopped. The optical stop is the location at which a physical iris is located. The iris is located within or at an end of the sixth zoom subgroup 159, and moves with that zoom subgroup. Note that in FIG. 78A, for example, the rim rays pass through S22 with room to spare, while in FIG. 78F, the rim rays are almost touching the extreme edges of S22 as they pass through the optical stop. This shows that the iris located at S22 must open as the focal length increases. To maintain a constant f-number at the image, the iris must “zoom” or change. In other words, the iris must be adjusted for constant aperture. A separate cam may be used to open or close the iris during zooming. In addition, it should be noted that all of the lens element surface apertures, set forth in the TABLE FOR FIGS. 77 AND 78A-78F, act as field stops at all focus and zoom positions as depicted in FIGS. 78A-78F. The size of the aperture of iris S22 is adjusted as the sixth zoom subgroup 159 moves axially, as described above, with respect to the maximum aperture diameters listed in the TABLE FOR FIGS. 77 AND 78A-78F and is given with its largest value in the TABLE FOR FIGS. 77 AND 78A-78F.
In the second exemplary IR embodiment of the zoom lens system, the sensor located at the image plane S23 is responsive not to light but to the amount of heat given off by the objects being viewed, and captures differences in the heat given off by the objects down to a Minimum Resolvable Temperature Difference (MRTD). To do this, the sensor averages the temperature of elements in the scene being viewed. The sensor ideally should not “see” any lens structure, otherwise the temperature of the lens structure would be averaged into the scene and cause image errors. Therefore, in embodiments of the present invention, the stop (i.e. the iris located at the stop) is part of the detector, and the detector including the stop is cooled to reduce electronic noise, producing a “cold stop.”
The six zoom subgroups 153-159 are each axially movable independently and their respective movements are coordinated by any convenient means, such as conventional mechanical devices such as cams or the like, to accomplish the desired zooming function.
FIGS. 79A-79F illustrate the diffraction modulation transfer function (MTF) for the same light rays entering the lens system at the relative field heights shown in FIGS. 78A-78F according to embodiments of the present invention. In FIGS. 79A-79F, the x-axis represents the spatial frequency (resolution) in cycles per millimeter, and the y-axis represents a relative modulation value (an indication of image quality). The diffraction MTF curves of FIGS. 79A-79F are polychromatic, using the same wavelengths and X and Y field fans, but with wavelength weights. Note that at a spatial frequency of about 15 cycles/mm, at the extreme right distal end of each of the plots, the diffraction MTF for all of the field fans in each of the plots are clustered with a modulation range of about 0.65 to 0.82. In general, diffraction MTFs greater than 0.50 are desired, and a lens is said to be “diffraction limited” (ideal) if the diffraction MTFs are greater than 80%. Thus, there is not much of a dropoff from the diffraction limit in the lens of the present invention. The maximum distortion in the six zoom positions of FIGS. 79A-79F is about 3.5%.
Although the present invention has been fully described in connection with embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications will become apparent to those skilled in the art. Such changes and modifications are to be understood as being included within the scope of the present invention as defined by the appended claims.

## Claims

1. An infrared zoom lens system for forming a final image of an object, said system having an object side and an image side and forming a first intermediate real image between the object and the final image, said system comprising:
a first lens group including at least two lens elements and located between the object and the first intermediate real image, said first lens group comprising at least one zoom subgroup which is moved to change the size (magnification) of the first intermediate real image;
a second lens group including at least two lens elements and located between the first intermediate real image and the final image, at least a portion of which is moved to change the size (magnification) of the final image; and
an optical stop located between the intermediate image and the final image;
wherein off-axis field beam chief rays first cross an optical axis of the infrared zoom lens system on the object side of the intermediate image and then cross the optical axis again at the optical stop; and
wherein a ratio of a maximum off-axis field beam rim ray to an axial field beam rim ray at a lens surface of the first lens group adjacent to object space at a longest focal length of the zoom lens system is less than about 1.25.

2. The infrared zoom lens system as recited in claim 1, wherein the optical stop is located between a last element surface of the second lens group and the final image.

3. The infrared zoom lens system as recited in claim 1, wherein the infrared zoom lens system is capable of forming the final image from received radiation in the range of about 3-5 microns.

4. The infrared zoom lens system as recited in claim 1, wherein the first lens group comprises five lens elements and the second lens group comprises five lens elements.

5. The infrared zoom lens system as recited in claim 1, wherein the first lens group and the second lens group comprise a seven group system with one axially stationary lens subgroup and six axially movable zoom subgroups.

6. The infrared zoom lens system as recited in claim 1, wherein the first lens group comprises three zoom subgroups and the second lens group comprises three zoom subgroups.

7. The infrared zoom lens system as recited in claim 1, wherein the first lens group comprises one axially stationary lens subgroup.

8. The infrared zoom lens system as recited in claim 1, wherein the lens elements include one or more germanium lens elements and one or more silicon lens elements.

9. The infrared zoom lens system as recited in claim 1, wherein at least one of the lens elements includes an aspheric surface.

10. The infrared zoom lens system as recited in claim 5, wherein the first lens group comprises a first lens subgroup of positive power, a first zoom subgroup of negative power, a second zoom subgroup of positive power, and a third zoom subgroup of positive power, and the second lens group comprises a fourth zoom subgroup of negative power, a fifth zoom subgroup of negative power, and a sixth zoom subgroup of positive power.

11. An infrared zoom lens system for forming a final image of an object, said system having an object side and an image side and forming a first intermediate real image between the object and the final image, said system comprising:
a first lens group including a first five lens elements and located between the object and the first intermediate real image, said first lens group comprising at least one zoom subgroup which is moved to change the size (magnification) of the first intermediate real image;
a second lens group including a second five lens elements and located between the first intermediate real image and the final image, at least a portion of which is moved to change the size (magnification) of the final image; and
an optical stop located between the intermediate image and the final image;
wherein off-axis field beam chief rays first cross an optical axis of the infrared zoom lens system on the object side of the intermediate image and then cross the optical axis again at the optical stop;
wherein a ratio of a maximum off-axis field beam rim ray to an axial field beam rim ray at a lens surface of the first lens group adjacent to object space at a longest focal length of the zoom lens system is less than about 1.25; and
wherein lens element surfaces, a location of an object on the object side identified as (Object), a location of the optical stop identified as (Stop), a location of the final image identified as (Image), radii of corresponding surfaces, distances from one surface to a next surface, material between a corresponding surface and the next surface, and a maximum diametric diameter of light rays passing through the corresponding surface have the following order, relationships and characteristics:























Radius of
Thickness or

Aperture



Sub-

Zoom
Curvature
Separation
Refractive
Diameter















Item
Group
Group
Surface
Position
(mm)
(mm)
Material
(mm)





















S0 (Object)

Infinity
25.000




120
151
152
S1
All
215.343
28.544
Silicon
317.642





S2
Z1
269.106*
9.864

308.262






Z2

57.468






Z3

108.517






Z4

117.957






Z5

132.937






Z6

135.615


122
151
153
S3
All
637.888
9.000
Germanium
187.169





S4
All
247.226
11.642

174.123


124
151
153
S5
All
228.929
8.000
Silicon
166.617





S6
Z1
161.278
244.587

157.148






Z2

220.842






Z3

150.487






Z4

74.335






Z5

22.911






Z6

11.974


126
151
154
S7
All
288.682
15.448
Silicon
176.490





S8
Z1
1321.765*
212.856

174.473






Z2

233.828






Z3

270.854






Z4

362.883






Z5

443.606






Z6

460.309


128
151
155
S9
All
83.756*
11.053
Silicon
105.651





S10
Z1
159.357
160.888

103.666






Z2

115.791






Z3

97.933






Z4

72.886






Z5

28.278






Z6

20.171





S11 (dummy)
Z1
Infinity
74.210






Z2

46.803






Z3

3.191






Z4

3.253






Z5

57.219






Z6

19.714


130
156
157
S12
All
−32.997
12.500
Silicon
29.867





S13
Z1
−45.308
1.830

36.698






Z2

29.317






Z3

74.625






Z4

73.197






Z5

0.800






Z6

1.897


132
156
158
S14
All
−28.877
10.206
Germanium
23.882





S15
Z1
−44.286
1.917

30.694






Z2

0.995






Z3

0.100






Z4

0.926






Z5

4.846






Z6

18.907


134
156
159
S16
All
6208.244
13.998
Germanium
37.741





S17
All
264.338
0.400

40.076


136


S18
All
171.855
11.452
Silicon
41.269





S19
All
−84.226
0.400

42.354


138


S20
All
−128.685
1.000
Silicon
41.072





S21
Z1
−156.416*
1.254

41.075






Z2

1.696






Z3

0.750






Z4

1.699






Z5

15.734






Z6

38.441





S22 (Stop)
All
Infinity
79.221





S23 (Image)
All
Infinity
0.000.