Retrofocus wide angle lens

A wide angle lens system of the retrofocus type is provided which includes two lens units. The first lens unit is of negative power and includes a combination of a positive element having a high dispersion and a negative element having a low dispersion for correction of lateral color. The second lens unit is of positive power and includes a combination of a positive element having a low dispersion and a negative element having a high dispersion for correction of longitudinal color. The lens units satisfy the relationship that the magnitude of f.sub.1 is less than about 1.15 times f.sub.2 and preferably satisfy the relationship that the magnitude of f.sub.1 is less than f.sub.0. The first and second lens units each preferably include an aspheric surface. Applications of the lens system include rear projection television systems wherein a single lens is used to project light from three LCD light valves onto a viewing screen.

FIELD OF THE INVENTION 
This invention relates to wide angle retrofocus type lenses having a long 
back focal length and a relatively compact size and to the use of such 
lenses in liquid crystal display (LCD) light valve projection televisions. 
BACKGROUND OF THE INVENTION 
Most of the LCD light valve projection TV systems currently under 
development can be broken into two broad classes: 1) those using multiple 
exit pupils where a separate lens is used to project each of three 
different color LCDs, and 2) single exit pupil systems where all three 
different color LCDs are projected through the same lens. 
In either case, the system can be of the transmissive type where light 
comes in from behind the liquid crystal panel and is modulated as it 
passes through the panel or of the reflective type where light enters 
through the front of the panel and is reflected back out towards the 
screen after having been modulated. 
Examples of such television systems and of lenses which can be used with 
such systems can be found in, for example, Taylor, U.S. Pat. No. 
4,189,211, Gagnon et al., U.S. Pat. No. 4,425,028, Gagnon, U.S. Pat. No. 
4,461,542, Ledebuhr, U.S. Pat. No. 4,826,311, Minefuji, U.S. Pat. No. 
4,913,540, EPO Patent Publication No. 311,116, and Russian Patent 
Publication No. 1,007,068. A lens described as being "retrotelecentric" is 
disclosed in Ikemori, U.S. Pat. No. 3,947,094. 
Systems having a single exit pupil solve the problem of color shift in the 
projected image and allow for a simpler design of the projection screen in 
that the screen does not need to perform mixing of the colors from the 
three lens systems. However, the projection lens must have a large 
separation between the LCD panels and the lens to accommodate the filters 
and beamsplitters used to combine the light from the different LCDs into a 
common beam for projection onto the screen by the lens. 
For rear projection applications, it is desirable to have as small an 
overall package size (set size) as possible. In terms of the optics, this 
means that the imaging conjugates should be made as small as possible 
while still maintaining a large image size. This, in turn, means that the 
projection lens must have a large field of view. Additionally, it is 
desirable to use lenses having a small physical size so as to reduce the 
sizes of the folding mirrors placed between the lens and the screen. 
Lenses having small physical sizes also help to further reduce the size of 
the overall TV package. 
The illumination of the LCD panel plays a very important role in the 
performance of an LCD projection TV. In particular, it is very important 
to match the location and size of the exit pupil of the illumination 
system with the entrance pupil of the lens to obtain a bright, 
uniformly-illuminated TV image. Since illumination optics generally work 
best when the exit pupil is located a long distance from the light source, 
it is desirable to use a projection lens with a long entrance pupil 
distance. 
The lens described below addresses all the above mentioned requirements and 
at the same time provides a high level of image quality and, in 
particular, a high level of correction of both lateral and longitudinal 
chromatic aberrations. 
SUMMARY OF THE INVENTION 
In view of the foregoing, it is an object of the present invention to 
provide a novel lens structure having: 1) a focal point a long distance 
from the lens (i.e., a long back focal length for light traveling from 
left to right in the figures), 2) a pupil a long distance from the lens 
(i.e., an exit pupil a long distance from the lens for light traveling 
from left to right in the figures), 3) a wide field of view (i.e., a field 
of view greater than about 25 degrees half or semi-field for light 
traveling from left to right in the figures), 4) small lens elements, and 
5) a high level of image quality. 
It is a further objection of the invention to provide a LCD projection 
television system having an improved lens system which provides a high 
level of image quality and an overall small set size. 
To achieve the foregoing and other objects, the invention provides a wide 
angle lens system of the retrofocus type comprising: 
(a) a first lens unit of negative power comprising: 
(i) a negative element; and 
(ii) a combination of two elements, one of the two elements being a 
positive element having a high dispersion and the other of the two 
elements being a negative element having a low dispersion; and 
(b) a second lens unit of positive power comprising: 
(i) a positive element; and 
(ii) a combination of two elements, one of the two elements being a 
positive element having a low dispersion and the other of the two elements 
being a negative element having a high dispersion. 
The elements making up the first and second units are chosen so that the 
absolute value of the focal length of the first lens unit f.sub.1 is less 
than about 1.15 times the focal length of the second lens unit f.sub.2. In 
certain preferred embodiments of the invention, the absolute value of 
f.sub.1 is smaller than the overall focal length f.sub.0 of the lens. To 
provide a high level of image quality, in addition to the high and low 
dispersion elements which provide for color correction, either or 
preferably both of the first and second lens units includes at least one 
aspheric surface. 
When used in a LCD projection television, the lens is arranged with the 
second lens unit nearer to the LCD panels. For this application, the lens' 
aperture stop is located between the first and second lens units at a 
point which is at or inside of the second unit's front focal point so that 
the image of the aperture stop formed by the second lens unit (the 
entrance pupil as seen from the LCD) is located a long distance from the 
LCD panel.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
As discussed above, the present invention relates to lens systems having 
two lens units separated by an air space wherein the first lens unit has a 
negative power and the second lens unit has a positive power and each unit 
includes a combination of two elements of low and high dispersion to 
provide overall good color correction for the lens. 
The first unit comprises at least one negative element, preferably a single 
negative meniscus element, and at least one combination of positive and 
negative elements having high and low dispersion properties described by a 
small and a large V-value, respectively. As used herein, high dispersion 
optical materials are those having V-values ranging from 20 to 50 for an 
index of refraction in the range from 1.85 to 1.5, respectively, while low 
dispersion materials are those having V-values ranging from 35 to 75 for 
the same range of indices of refraction. At least one of the surfaces in 
the first unit may be aspherical. 
The second unit comprises at least one positive element and a combination 
of positive and negative elements having dispersion characteristics 
described by a large and a small V-value, respectively. The second unit 
may also contain at least one aspherical surface. 
The aperture stop of the lens is preferably positioned between the first 
and second units. When the lens is designed for use only at its wide open, 
maximum aperture, the aperture stop may be inside one of the elements in 
the vicinity of the airspace between the two units. 
When the lens is used with a LCD panel, the aperture stop preferably lies 
inside the second unit's front focal point to assure that a virtual image 
of the stop, which comprises the entrance pupil of the lens as seen from 
the LCD panel, is at a considerable distance away from the panel. With 
reference to the figures, the second unit's front focal point in question 
is that lying to the left of the second unit, i.e., towards the first 
unit. When the position of the aperture stop is coincident with the front 
focal point of the second unit, the entrance pupil of the lens as seen 
from the LCD panel is imaged at infinity. 
To provide a long distance between the second lens unit and the lens' right 
focal point, i.e., a long back focal length for light traveling from left 
to right in the figures, and to maintain a compact size of the lens, the 
first unit should be quite strong. In particular, the magnitude of f.sub.1 
should be less than about 1.15 times f.sub.2. For many applications, the 
magnitude of f.sub.1 is preferably less than the focal length of the whole 
lens f.sub.0. 
A strong negative power for he first unit causes a relatively large 
contribution to distortion which may be corrected by the use of an 
aspherical surface as a part of that unit. Additionally, contributions to 
the correction of coma and astigmatism may also be obtained from the use 
of such an asphere. 
When the field of view of the lens becomes large, e.g., a semi-field angle 
of about 35.degree., additional aspherical surfaces may be used in the 
first unit to obtain better control of off-axis aberrations. 
With regard to chromatic aberrations, the combination of a positive element 
having a small V-value and a negative element having a large V-value in 
the first unit allows for good correction of lateral color and chromatic 
variation of distortion. 
The second unit will typically have a focal length similar to the focal 
length of the lens as a whole. To provide correction for spherical 
aberration of the lens, the second unit preferably includes one or more 
aspherical surfaces. These one or more aspherical surfaces can also be 
used to achieve a high level of correction of spherical aberration of the 
entrance pupil of the lens as seen from a LCD display. Correcting this 
aberration is important in order to provide a good match between the 
entrance pupil of the lens and the exit pupil of the illumination system 
to assure that all the light from the illumination system will go through 
the projection lens. 
With regard to chromatic aberrations, the combination of positive and 
negative elements with large and small V-values, respectively, in the 
second unit allows for the correction of axial (longitudinal) color to be 
achieved. 
FIGS. 1 to 8 illustrate various lens systems constructed in accordance with 
the invention. Corresponding lens prescriptions appear in Tables 1 to 8, 
respectively. A summary of various properties of these systems appears in 
Tables 9 and 10. In these figures and tables, the letter "L" is used to 
designate individual lenses, the letter "S" to designate lens surfaces, 
the letters "IS" to designate the image surface, and the letter "G" to 
designate lens units or groups. The lens surfaces within the two lens 
units is summarized in Table 11. 
The N.sub.e and V.sub.e values given in Tables 1-8 represent the indices of 
refraction and Abbe values for the various lenses at a wavelength of 
0.5461 microns. The aspheric coefficients set forth in the tables are for 
use in the following equation: 
##EQU1## 
where z is the surface sag at a distance y from the optical axis of the 
system, c is the curvature of the lens at the optical axis, and k is a 
conic constant, which for the lenses of Tables 1-8 is zero. 
In FIGS. 1-8, light is assumed to propagate from left to right, i.e., from 
the system's long conjugate towards its short conjugate. In the case of a 
projection television using a liquid crystal display, light will propagate 
in the opposite direction, i.e., from right to left. That is, for such 
systems, the LCD will be located to the right of the second lens unit and 
the viewing screen will be located to the left of the first lens unit. In 
FIGS. 1, 3, and 5-7 an LCD-type display is schematically illustrated by 
the planar block to the right of G2. 
As can be seen from Table 9, the magnitude of f.sub.1 is less than about 
1.15 times f.sub.2 for all the examples, the magnitude of f.sub.1 is less 
than f.sub.0 for Examples 1 and 3-7, and f.sub.2 is similar to f.sub.0 for 
all of the examples and is within 20% of f.sub.0 for Examples 1-4. As also 
shown in this table, all of the examples have a half field of view above 
25.degree., i.e., all of the lenses are wide angle lenses. 
FIG. 9 is a schematic diagram of a LCD light valve projection television 10 
constructed in accordance with the invention. As shown in this figure, 
projection television 10 includes cabinet 12 having projection screen 14 
along its front face. The image to be projected is formed by module 16 
which includes a light source, three LCD panels, and a set of dichroic 
beamsplitters for combining the light from the three panels into a single 
beam. Various commercially available components known in the art can be 
used to construct module 16. 
The single, three-color beam produced by module 16 is projected by lens 13 
onto mirror 18 and ultimately to screen 14. Lens 13 is constructed in 
accordance with the present invention and thus forms a high quality image 
on the screen while at the same time allowing cabinet 12 to have an 
overall small size. 
Although specific embodiments of the invention have been described and 
illustrated, it is to be understood that a variety of modifications which 
do not depart from the scope and spirit of the invention will be evident 
to persons of ordinary skill in the art from the foregoing disclosure. The 
following claims are intended to cover the specific embodiments set forth 
herein as well as such modifications, variations, and equivalents. 
TABLE 1 
__________________________________________________________________________ 
AXIAL DISTANCE 
SURFACE BETWEEN SURFACES 
LENS RADIUS (mm) 
(mm) Ne Ve 
__________________________________________________________________________ 
S1 106.0349 
L1 5.0000 1.49378 
56.95 
S2 34.6801 
16.7055 
S3 65.9226 
L2 15.3782 1.62408 
36.05 
S4 -162.4377 
L3 3.0000 1.74435 
52.43 
S5 47.3852 
2.9332 
S6 38.7648 
L4 11.0000 1.49378 
56.95 
S7 108.0509 
19.2033 
S8 -135.8052 
L5 12.0000 1.65222 
33.60 
S9 -22.9143 
L6 2.0000 1.81080 
40.40 
S10 -85.7226 
22.8029 
S11 -124.4576 
L7 9.0000 1.51872 
64.02 
S12 -54.4326 
L8 4.0000 1.81264 
25.27 
S13 -491.9398 
1.7144 
S14 -214.1831 
L9 10.0152 1.49378 
56.95 
S15 -63.8143 
.2000 
S16 -1344.1290 
L10 23.0473 1.59142 
61.03 
S17 -60.7625 
250.0000 
S18 .infin. 
L11 7.5000 1.52458 
59.20 
S19 .infin. 
.0087 
__________________________________________________________________________ 
ASPHERICAL SURFACE DATA: 
S D E F G H I 
__________________________________________________________________________ 
S1 .14966E-05 
-.12247E-09 
-.34536E-13 
.16546E-15 
-.87797E-19 
.18616E-22 
S6 -.75901E-08 
-.61143E-09 
.60280E-11 
.39748E-15 
-.11120E-16 
.13167E-19 
S15 
.54967E-06 
.16532E-09 
.13261E-12 
-.19777E-16 
.88289E-20 
-.22085E-23 
__________________________________________________________________________ 
TABLE 2 
__________________________________________________________________________ 
AXIAL DISTANCE 
SURFACE BETWEEN SURFACES 
LENS RADIUS (mm) 
(mm) Ne Ve 
__________________________________________________________________________ 
S1 72.6598 
L1 5.0000 1.49378 
56.95 
S2 32.9936 
20.2616 
S3 431.1641 
L2 15.0000 1.62408 
36.05 
S4 -64.8330 
L3 3.0000 1.74435 
52.43 
S5 886.8083 
15.7010 
S6 333.5692 
L4 3.0000 1.83930 
37.05 
S7 26.6827 
L5 14.0000 1.67765 
31.94 
S8 -156.6556 
1.1643 
S9 -115.3066 
L6 4.0000 1.49354 
57.34 
S10 -126.3225 
26.9338 
S11 -629.7960 
L7 12.0000 1.51872 
64.02 
S12 -61.1854 
L8 4.0000 1.74706 
27.56 
S13 .infin. 
3.7387 
S14 -191.8310 
L9 10.0000 1.49378 
56.95 
S15 -68.2860 
.2000 
S16 -188.4562 
L10 20.0000 1.51872 
64.02 
S17 -54.0627 
250.0632 
__________________________________________________________________________ 
ASPHERICAL SURFACE DATA: 
S D E F G H I 
__________________________________________________________________________ 
S1 .11495E-05 
.80396E-10 
.15864E-12 
.66273E-16 
-.94058E-19 
.50338E-22 
S10 
-.80611E-06 
-.22254E-08 
-.12837E-11 
.35390E-14 
.79124E-17 
-.32865E-19 
S15 
.58121E-06 
.21925E-09 
-.21401E-14 
-.36387E-16 
.37385E-19 
-.10942E-22 
__________________________________________________________________________ 
TABLE 3 
__________________________________________________________________________ 
AXIAL DISTANCE 
SURFACE BETWEEN SURFACES 
LENS RADIUS (mm) 
(mm) Ne Ve 
__________________________________________________________________________ 
S1 112.8827 
L1 8.0000 1.49354 
57.34 
S2 47.0795 
80.18 
S3 -83.8357 
L2 3.0000 1.79014 
43.71 
S4 27.1015 
L3 12.0000 1.79192 
25.50 
S5 -160.8239 
15.6911 
S6 376.5779 
L4 13.0000 1.51872 
64.02 
S7 -29.5420 
L5 3.0000 1.81264 
25.27 
S8 -282.5645 
9.9778 
S9 -80.4535 
L6 9.0000 1.49354 
57.34 
S10 -54.6521 
1.0000 
S11 -360.6606 
L7 17.0000 1.51872 
64.02 
S12 -46.7772 
235.65 
S13 .infin. 
L8 2.5000 1.52458 
59.20 
S14 .infin. 
__________________________________________________________________________ 
ASPHERICAL SURFACE DATA: 
S D E F G H I 
__________________________________________________________________________ 
S1 
.50592E-06 
.16167E-10 
-.28644E-13 
.36220E-16 
-.12681E-19 
.17418E-23 
S9 
-.18003E-05 
.51642E-09 
-.27362E-11 
.62083E-15 
.30851E-17 
-.30618E-20 
__________________________________________________________________________ 
TABLE 4 
__________________________________________________________________________ 
AXIAL DISTANCE 
SURFACE BETWEEN SURFACES 
LENS RADIUS (mm) 
(mm) Ne Ve 
__________________________________________________________________________ 
S1 232.5495 
L1 15.0000 1.48951 
49.93 
S2 -2439.0800 
.0000 
S3 146.7255 
L2 5.5000 1.71615 
53.68 
S4 61.2762 
80.1134 
S5 118.8177 
L3 3.0000 1.71615 
53.68 
S6 28.3211 
L4 15.0000 1.72733 
29.16 
S7 56.1212 
60.1199 
S8 -449.4696 
L5 12.0000 1.51872 
64.02 
S9 -37.7949 
L6 3.0000 1.81264 
25.27 
S10 -80.3022 
13.3733 
S11 -64.1311 
L7 10.0000 1.49354 
57.34 
S12 -71.9387 
1.0000 
S13 -250.9194 
L8 12.0000 1.51872 
64.02 
S14 -51.3697 
231.5135 
__________________________________________________________________________ 
ASPHERICAL SURFACE DATA: 
S D E F G H I 
__________________________________________________________________________ 
S11 
-.11683E-05 
-.34876E-09 
-.68143E-13 
-.68563E-15 
.62876E-18 
-.33575E-21 
__________________________________________________________________________ 
TABLE 5 
__________________________________________________________________________ 
AXIAL DISTANCE 
SURFACE BETWEEN SURFACES 
LENS RADIUS (mm) 
(mm) Ne Ve 
__________________________________________________________________________ 
S1 166.7893 
L1 7.0000 1.49354 
57.34 
S2 53.7244 
29.0554 
S3 -2413.0950 
L2 6.0000 1.49354 
57.34 
S4 77.5337 
12.1062 
S5 -439.4338 
L3 5.0000 1.49354 
57.34 
S6 -470.1938 
47.7318 
S7 -119.3178 
L4 2.0000 1.74690 
49.00 
S8 21.7550 
L5 14.5000 1.81264 
25.27 
S9 -151.4782 
1.0000 
S10 128.5317 
L6 11.0000 1.57829 
41.25 
S11 -26.9117 
L7 2.0000 1.83930 
37.05 
S12 49.7160 
.5087 
S13 43.9925 
L8 16.1897 1.51978 
51.91 
S14 -24.1324 
L9 2.0000 1.81264 
25.27 
S15 214.6256 
2.6536 
S16 149.7545 
L10 18.5051 1.51872 
64.02 
S17 -44.8523 
.2000 
S18 -63.4312 
L11 5.0000 1.49354 
57.34 
S19 -57.8218 
.2000 
S20 -571.4227 
L12 22.1721 1.51872 
64.02 
S21 -48.3718 
170.0000 
S22 .infin. 
L13 3.5000 1.51872 
64.02 
S23 .infin. 
.0010 
__________________________________________________________________________ 
ASPHERICAL SURFACE DATA: 
S D E F G H I 
__________________________________________________________________________ 
S1 .81353E-06 
.26733E-10 
-.12926E-12 
.80374E-16 
-.21787E-19 
.28735E-23 
S4 -.14186E-05 
-.24254E-08 
.20304E-11 
-.20978E-14 
.27671E-17 
-.11348E-20 
S5 -.22382E-05 
-.26539E-08 
.34725E-11 
-.28534E-15 
-.86110E-18 
.20518E-21 
S19 
.16311E-05 
.76203E-09 
.58142E-12 
.12553E.15 
-.20767E-18 
.45314E-22 
__________________________________________________________________________ 
TABLE 6 
__________________________________________________________________________ 
AXIAL DISTANCE 
SURFACE BETWEEN SURFACES 
LENS RADIUS (mm) 
(mm) Ne Ve 
__________________________________________________________________________ 
S1 122.2828 
L1 7.0000 1.49354 
57.34 
S2 42.2151 
30.8830 
S3 111.8497 
L2 6.0000 1.49354 
57.34 
S4 46.1144 
27.3549 
S5 245.3543 
L3 10.0000 1.49354 
57.34 
S6 -148.5418 
16.0000 
S7 -336.6699 
L4 2.5000 1.81080 
40.40 
S8 18.6212 
L5 15.0000 1.81264 
25.27 
S9 62.8765 
1.0000 
S10 70.1130 
L6 14.0000 1.57829 
41.25 
S11 -23.7888 
L7 2.0000 1.81080 
40.40 
S12 -206.8242 
18.7122 
S13 490.3304 
L8 15.0000 1.51872 
64.02 
S14 -39.3481 
L9 3.5000 1.81264 
25.27 
S15 -1039.8430 
4.2183 
S16 -118.0000 
L10 7.0000 1.49354 
57.34 
S17 -63.3925 
.2000 
S18 -1029.7890 
L11 18.9556 1.51872 
64.02 
S19 -57.1428 
.0000 
S20 -177.7165 
L12 18.1470 1.51872 
64.02 
S21 -61.2271 
170.0000 
S22 .infin. 
L13 3.5000 1.51872 
64.02 
S23 .infin. 
-.0229 
__________________________________________________________________________ 
ASPHERICAL SURFACE DATA: 
S D E F G H I 
__________________________________________________________________________ 
S1 .78755E-06 
.18026E-11 
-.13107E-12 
.81066E-16 
-.19327E-19 
.18622E-23 
S4 .19799E-06 
-.54141E-09 
.25665E-12 
.17650E-15 
.10338E-18 
-.30784E-21 
S5 .12025E-05 
.71844E-09 
.51745E-12 
.39564E-15 
.21664E-18 
-.30784E-21 
S17 
.16304E-05 
.42299E-09 
.60173E-12 
-.26955E-15 
-.13124E-18 
.82540E-22 
__________________________________________________________________________ 
TABLE 7 
__________________________________________________________________________ 
AXIAL DISTANCE 
SURFACE BETWEEN SURFACES 
LENS RADIUS (mm) 
(mm) Ne Ve 
__________________________________________________________________________ 
S1 -562.9973 
L1 7.0000 1.49354 
57.34 
S2 69.7026 
29.2336 
S3 -171.8047 
L2 6.0000 1.49354 
57.34 
S4 -472.6218 
51.1723 
S5 -179.9509 
L3 2.5000 1.81080 
40.40 
S6 19.7244 
L4 15.0000 1.81264 
25.27 
S7 202.5100 
1.0000 
S8 92.9324 
L5 9.0000 1.57829 
41.25 
S9 -28.8010 
L6 2.0000 1.81080 
40.40 
S10 -3595.3950 
25.4503 
S11 241.4227 
L7 15.0000 1.51872 
64.02 
S12 -41.4693 
L8 3.5000 1.81264 
25.27 
S13 -1732.9750 
4.0150 
S14 -118.0000 
L9 7.0000 1.49354 
57.34 
S15 -75.5824 
.2000 
S16 2060.4940 
L10 18.9540 1.51872 
64.02 
S17 -63.8123 
.0000 
S18 -215.5601 
L11 18.1276 1.51872 
64.02 
S19 -62.7541 
170.0000 
S20 .infin. 
L12 3.5000 1.51872 
64.02 
S21 .infin. 
.0012 
__________________________________________________________________________ 
ASPHERICAL SURFACE DATA: 
S D E F G H I 
__________________________________________________________________________ 
S1 .14354E-05 
-.79148E-10 
-.13743E-12 
.82937E-16 
-.19166E-19 
.17419E-23 
S4 .13853E-05 
-.32699E-09 
.31083E-13 
.96594E-17 
-.34114E-20 
-.12423E-23 
S15 
.15628E-05 
.46105E-09 
.28789E-12 
-.22082E-15 
.37941E-19 
-.65996E-24 
__________________________________________________________________________ 
TABLE 8 
__________________________________________________________________________ 
AXIAL DISTANCE 
SURFACE BETWEEN SURFACES 
LENS RADIUS (mm) 
(mm) Ne Ve 
__________________________________________________________________________ 
S1 93.1619 
L1 7.0000 1.49354 
57.34 
S2 46.6574 
24.3937 
S3 158.9949 
L2 6.0000 1.64128 
55.19 
S4 53.0765 
78.0459 
S5 -155.9050 
L3 2.2182 1.83930 
37.05 
S6 22.2678 
L4 12.0000 1.81264 
25.27 
S7 -219.5400 
23.8650 
S8 -260.1993 
L5 11.0000 1.51872 
64.02 
S9 -33.9132 
L6 2.6619 1.81264 
25.27 
S10 372.8117 
.2000 
S11 110.0612 
L7 12.0000 1.49354 
57.34 
S12 -89.6261 
2.8000 
S13 -80.3868 
L8 10.0000 1.51872 
64.02 
S14 -52.1945 
.0000 
S15 -257.6454 
L9 17.0000 1.51872 
64.02 
S16 -50.7737 
170.0131 
__________________________________________________________________________ 
ASPHERICAL SURFACE DATA: 
S D E F G H I 
__________________________________________________________________________ 
S1 .48361E-07 
.62870E-09 
-.27386E-12 
.50310E-16 
.73191E-22 
-.91572E-25 
S12 
.31608E-05 
-.18013E-08 
.71687E-11 
-.10824E-13 
.77148E-17 
-.21739E-20 
__________________________________________________________________________ 
TABLE 9 
__________________________________________________________________________ 
1/2 Field 
of 
Example 
f.sub.0 
f.sub. 
f.sub.2 
1.15 .multidot. f.sub.2 
Mag. View 
f/No.* 
__________________________________________________________________________ 
1 108.60 
-99.34 
109.51 
125.94 
-.8604E-01 
37.0.degree. 
3.68 
2 108.24 
-121.06 
120.55 
138.63 
-.8604E-01 
36.3.degree. 
3.68 
3 91.52 
-87.11 
105.18 
120.96 
-.4744E-01 
28.0.degree. 
4.30 
4 89.97 
-83.72 
107.12 
123.19 
-.3000E-01 
28.0.degree. 
4.37 
5 41.06 
-17.03 
55.11 
63.38 
-.4673E-01 
41.6.degree. 
2.87 
6 40.50 
-32.05 
73.88 
84.96 
-.4673E-01 
42.0.degree. 
2.87 
7 40.51 
-33.35 
76.65 
88.15 
-.4673E-01 
42.0.degree. 
2.87 
8 41.21 
-51.57 
85.07 
97.83 
-.4673E-01 
41.7.degree. 
2.87 
__________________________________________________________________________ 
*For object at infinity. 
TABLE 10 
______________________________________ 
Left Focal 
Aperture Point of Exit Back Focal 
Example 
Stop.sup.1 
Second Unit.sup.2 
Pupil.sup.3 
Distance.sup.4 
f.sub.0 
______________________________________ 
1 1.00 -68.10 -386.7 
245.5 108.60 
2 1.87 -77.50 -392.8 
240.8 108.24 
3 11.78 -55.79 -327.3 
232.9 91.52 
4 45.12 -64.40 -350.3 
228.8 89.97 
5 21.45 -16.60 -226.0 
170.4 41.06 
6 23.10 -29.40 -256.8 
170.4 40.50 
7 22.80 -33.00 -288.6 
170.4 40.51 
8 17.12 -41.24 -280.0 
168.1 41.21 
______________________________________ 
.sup.1 Distance from last surface of the first lens unit. 
.sup.2 Distance from the first surface of the second lens unit for light 
traveling from left to right in the figures. 
.sup.3 Distance from image surface for light traveling from left to right 
in the figures. 
.sup.4 Distance from last optical surface of the second lens unit to the 
image point for an object at infinity for light traveling from left to 
right in the figures. 
TABLE 11 
______________________________________ 
Example G1 G2 
______________________________________ 
1 S1-S10 S11-S17 
2 S1-S10 S11-S17 
3 S1-S5 S6-S12 
4 S1-S7 S8-S14 
5 S1-S12 S13-S21 
6 S1-S12 S13-S21 
7 S1-S10 S11-S19 
8 S1-S7 S8-S16 
______________________________________