Patent Publication Number: US-6906865-B2

Title: Light altering device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This is a divisional of U.S. application Ser. No. 09/728,756 filed Dec. 4, 2000 now U.S. Pat. No. 6,833,962 by the same inventor, and claims priority therefrom. This divisional application is being filed in response to a restriction requirement in that prior application and contains rewritten and/or additional claims to the restricted subject matter. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to the field of radiation manipulation. In particular, the invention relates a method and apparatus for altering a beam of light or radiant energy. 
   2. Description of Related Art 
   Heretofore, light has been manipulated to produce an alignment field with laser based equipment as shown in U.S. Pat. No. 3,588,249 where a collimated laser beam is rotated 360 degrees about an axis to establish an alignment plane. Remote receivers in the vicinity may detect the laser beam as it sweeps past, and provide a visual or audible indication when they are aligned in the laser plane. While this rotating beacon technique provides results that are quite useful over long ranges, the cost of the mechanical and optical structures for implementing the technique with the desired amount of accuracy is relatively high. Also, the plane is more difficult to locate if the receiver is moved through the plane before the beam strikes its detector. 
   An improvement is disclosed in U.S. Pat. No. 4,674,870 that includes a laser alignment system employing a transmitter and one or more receivers. The transmitter produces an alignment field by projecting laser energy in a non-planar reference cone, and the receivers locate this reference cone with photodetectors. The laser energy in the alignment field is modulated at 8 kHz and the signals produced by the photodetectors are filtered and amplified to increase the range of the system. Each receiver operates a display, which indicates when it is aligned in the reference cone, and it produces an out-of-level indication when the transmitter is not properly aligned. 
   A transmitter for an alignment system is shown in U.S. Pat. No. 4,679,937 in which a field of electromagnetic radiation is propagated in a non-planar reference cone. The transmitter includes a source for providing a collimated beam of electromagnetic radiation directed parallel to a beam axis. A cantilever strand supports a bob within the beam. The bob has a conical reflection surface to reflect the collimated beam conically. Optimally, the cantilever stand and bob are chosen to provide a deflection between the bob and plumb which is substantially one-half of any angular error between the beam axis and plumb. In a preferred form, a housing surrounds the bob and has inner and outer surfaces, which minimize temperature effects on the orientation of the reference plane. In addition, detectors are provided to sense when the angular error between the beam axis and plumb is outside of an acceptable range. Other leveling devices are shown in U.S. Pat. Nos. 5,914,778; 5,940,557; 5,994,688; 6,005,719 and 6,009,630. 
   Obviously, in view of the above prior art, there is still a need for a cost effective level line system. 
   SUMMARY OF THE INVENTION 
   Accordingly, in one aspect of the present invention, a low cost, light-altering device in the form of a hollow tube is disclosed for use in an optical level line system. The system includes an input beam of light or radiant energy that enters a side of the hollow glass tube. Light emerges from the tube radiating in a nearly 360 degree disc pattern forming a disc of ever expanding light. When the light strikes an enclosed or circular surface, a bright line or ring of light is produced on the surface. This ring can be generated for X, X and Y, and X, Y, and Z axes, by employing an individual light-altering device per axis, thereby supplying a line or ring for each axis. The lines or rings of light are ideally suited, for example, for laser line leveling applications. 
   In another aspect of the present invention, an input beam of light or visible radiation enters a side of a light-altering device in the form of a capillary array of small tubes. The light emerges from the array radiating in a nearly 360 degree disc pattern forming a disc of ever expanding light. When the light strikes an enclosed surface, a bright line or ring of light is produced on the surface. This ring can be generated for X, X and Y, and X, Y, and Z axes, by employing an individual light-altering device per axis, thereby supplying a line or ring for each axis. 
   In a third aspect of the present invention, an input beam of light or visible radiation enters a side of light altering device comprising a fiber optic rod. The light emerges from the rod radiating in a nearly 360 degree disc pattern forming a disc of ever expanding light. When the light strikes an enclosed surface, a bright line or ring of light is produced on the surface. This ring can be generated for X, X and Y, and X, Y, and Z axes, by employing an individual light-altering device per axis, thereby supplying a line or ring for each axis. 
   In a fourth aspect of the present invention, a low cost, light altering device is disclosed for use in an optical level line system. The system includes an input beam of light or visible radiation that enters a side of the light altering device that includes a hollow tube within a hollow tube. The light emerges from the tubes radiating in a nearly 360 degree disc pattern forming a disc of ever expanding light. When the light strikes an enclosed surface, a bright line or ring of light is produced on the surface. This ring can be generated for X, X and Y, and X, Y, and Z axes, by employing an individual light-altering device per axis, thereby supplying a line or ring for each axis. 
   These and other features and advantages of the invention are described in or apparent from the following detailed description on the exemplary embodiments. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other features of the instant invention will be apparent and easily understood from a further reading of the specification, claims and by reference to the accompanying drawings in which: 
       FIG. 1  is a top view of an exemplary embodiment of a light altering device in accordance with the present invention that employs a hollow tube, rod or capillary member(s). 
       FIG. 2  is a top view of another exemplary embodiment of a light-altering device in accordance with the present invention that employs a capillary array. 
       FIG. 3  is a top view of yet another exemplary embodiment of a light altering device in accordance with the present invention that employs a hollow tube within a hollow tube. 
       FIG. 4  is a top view of yet another exemplary embodiment of a light altering device in accordance with the present invention that employs a fiber optic rod. 
       FIG. 5  is a top view of still another exemplary embodiment of a light altering device in accordance with the present invention that employs a gap between a rod and a reflecting plane. 
       FIG. 6  is a top view of another embodiment of the present invention that is adaptable to produce a light reference plane of less than 360 degrees. 
       FIG. 7  is a side view of a light-altering device in accordance with the present invention that employs a plumb bob. 
       FIG. 8  is yet another embodiment of the light altering device of the present invention employing a concave or convex shaped reflector. 
       FIG. 9  is an embodiment of a light altering device of the present invention that employs a concave, conical or parabolic reflector having a hole cut in its side to allow the projection of light. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   In accordance with the present invention, a novel Light Altering Device (LAD) and method is disclosed to alter a beam of light or radiant energy from laser sources. This LAD dramatically changes an input beam of light or radiant energy&#39;s properties. As an example, a laser beam entering the LAD is altered such that the light emerges radiating in a substantially 360 degree disc pattern. This pattern can be obtained employing a variety of materials and geometries. One exemplary embodiment of the present invention employing a LAD is shown in FIG.  1 . Here, a laser beam  12  of laser  10  is shown entering the side of a LAD  15  in the form of a hollow glass tube  16 . Light emerges from tube  16  radiating in the direction of arrows  11  in a 360 degree disc pattern  17 . Thus, a disc is formed of ever emerging light. An enclosure, for example, a circular screen placed a given radius from the tube will allow an observer to view a bright ring of light on the screen surface. In addition, the uniformity of the light distribution around the radius is quite uniform. The light ring still maintains the optical properties of the directed beam. That is, polarization of the directed beam remains the same around the radius of the ring of light. Also, if the directed beam is such that it is focussed to a point 3 meters from where the tube may be inserted, when the tube is inserted the focal point remains relatively unchanged. 
   A tube  16  made of glass, plastic, gelatin, etc., with the proper diameter, wall thickness, index of refraction, etc., with a red laser input, can produce an emerging dotted ring of red light. That is, a black and red series of dots (dashes) around the disc will result. The interference and/or diffraction properties of light are responsible for this effect. 
   In another embodiment of the present invention in  FIG. 2 , LAD device  15  includes a capillary array  20  of hollow glass tubes. As shown, laser beam  12  of laser  10  enters a side of capillary array  20  with light radiating from the capillary array in a disc pattern of about 360 degrees. Thus, again a disc is formed of ever emerging light  17  in the direction of arrows  11 . A circular screen placed a given radius from the array will again allow an observer to view a bright ring of light  17  on a surface of the screen. 
   In the embodiment of the present invention shown in  FIG. 3 , laser  10  directs an input laser beam  12  into a surface of LAD  15  which comprises a combination of hollow tubes  30  and  31 , with hollow tube  30  placed within hollow tube  31 . As a result, light radiates from the hollow tubes  30  and  31  in a disc pattern of approximately 360 degrees forming an ever emerging light  17  in the direction of arrows  11 . A circular screen placed a given radius from the tubes will again allow an observer to view a bright ring of light  17  on a surface of the screen. 
   In the embodiment of the present invention shown in  FIG. 4 , laser  10  directs an input laser beam  12  into a surface of LAD  15  which comprises a fiber optic rod  25 . As a result of laser beam  12  striking the surface of fiber optic rod  25 , light radiates from the rod in the direction of arrows  11  in a disc pattern of approximately 360 degrees forming an ever emerging ring of light  17 . A circular screen placed a given radius from the tubes will again allow an observer to view a bright ring of light  17  on a surface of the screen. A fiber optic rod 6 mm in diameter displays a fairly uniform brightness around the rod where the beam enters. This scattered light seems uniform and so does the emerging beam. However, there is no visible light emerging from either of the polished ends of the rod. Therefore, there is minimal light loss into the fibers, thereby indicating an efficient reflection at the cladding interface. It is believed that there are multiple reflections within and/or around the outside of the fiber optic rod. The light, in this case, reflects off small micron diameter fibers, for example, about 13 microns, all encircling and contained in the ¼ inch diameter fiber optic rod, without a significant drop in light energy. That is, the total power emitted by the fiber optic rod is quite close to the power of the light directed into the rod. However, some scattered light is noticed around the circumference of the rod, but is only as wide as the entering light beam and does not appear to be very significant. 
   A method for efficiently utilizing almost all of the light generated, while providing a beam over 180 degrees or so, is accomplished by employing a light altering-device in contact with a glass surface contacting a mirror with a hole through it. In the embodiment of the present invention shown in  FIG. 5 , a laser  10  directs a laser input beam  12  through a channel  16  cut through mirror  13 . Laser beam  12  enters a glass member  14  as it is directed towards LAD  15  in the form of a fiber optic rod  18 . Glass  14  serves as a spacer member to force a controlled and parallel gap between LAD  15  in the form of fiber optic rod  18  and reflecting plane  19  of mirror  13 . As shown by arrows  11 , some light is reflected off the glass surface, while other rays of light are directed toward the mirror, striking the mirror, and reflecting off the mirror in multiple directions whereby it is multi-reflected to provide an emerging semi-circular beam of 180 degrees, or so. All of these reflections occur in the same plane that the beam strikes the LAD. Of course, using a mirror without a hole or channel can be employed by aiming the laser-input beam directly at the LAD from the side. That is, at an angle slightly greater than 90 degrees from the laser beam  12  shown in FIG.  5 . 
   It should be understood that other methods may be employed to alter light beams for special purposes or special results. For example, to improve beam uniformity about its circumference, mirrored coatings may be applied to the appropriate regions on the outer surfaces of the rod or tube(s) to direct light to the less bright regions of the beam. Also, the altering of the cross-sectional shape of the rod or tube to be oval, spherical, or have a flat areas on the circumference, etc., can provide special beneficial light patterns. 
   LAD units may also employ light sources other than lasers for illumination sources. This can include point or line sources, single colors, white light, etc. In fact, for special applications, multiple laser or light sources can be employed such that each individual source is aimed directly into a single LAD, without the light losses typically associated with uniting multiple light beams. 
   Hereinbefore, a LAD has been described that produces nearly a 360 degree circle of light. In some instances, there are times when it is preferable to employ only a portion of a circle of light, for example, 90 to 180 degrees for line making purposes. In those instances, the embodiment of the present invention shown in  FIG. 6  is employed that comprises a substrate  55  with a channel  16  therein and is aligned to another substrate  57  orthogonally. LAD  15  is positioned at an intersection of substrates  55  and  57  on top of a mirrored face  13  of the substrates. In this configuration, a 90 degree portion of a circle is created by a beam  12  from laser  10  applied through channel  16  in substrate  55 . The laser beam contacts LAD  15  and light emerges from the LAD, as shown by lines  17 , initially in all directions as shown by arrows  11 . However, mirrors  13  redirect the light such that it is contained approximately within the 90 degrees formed by the mirrors. By moving mirror  57  relative to mirror  55  a larger angular coverage can be attained as shown by arrow  58 . It should be understood that substrates  55  and  57  could be made of glass with mirrors  13  being placed on the opposite face of the substrates. 
   In  FIG. 7 , a plumb bob laser leveling apparatus  60  is shown that includes a LAD  15  positioned within plumb bob  62 . Spherical plumb bob  62  is fashioned having two hemispheres separated by a narrow transparent member  64  which encompasses the 360 degrees of the sphere&#39;s equator. A LAD  15  is positioned within the space provided between the two halves of the bob in order to provide a circle of light. The bob can be suspended from a string, a flat metal tape, e.g., a measuring tape in conjunction with a metal ring  69 , or attached to a wall, suspended from a door frame or ceiling, or operate hanging from a cross arm rod attached to a base or cantilevered from the base resting on a floor. The bob can have most any shape and is unique in that it automatically rests in a straight down position. This principle dictates that a plane cut through the bob orthogonal to the string direction can be useful for floor leveling. Thus, a LAD unit properly aligned/positioned within the bob allows the LAD to produce a circle of light for reference purposes, e.g., to achieve floor flatness. While it is preferred to center the weight distribution of the laser and LAD within the housing of the bob and spacer members, it may not be critical, since it should be much less than the mass of the bob. The bob weight can significantly dominate over the weight distribution of the LAD. 
   In operation, laser  10  supplies a beam of light  12  onto mirror  65  that deflects the light in a straight line into LAD  15 . The laser beam emerges from LAD  15  as an ever-expanding ring of light in the direction of arrows  11 . For best results, the mirror should be slightly wider than the beam width. 
   Concave and convex cylindrical reflectors can be useful for generating unique light patterns. In the method and apparatus shown in  FIG. 8 , laser beam  12  of laser  10  passes through a hole in the concave and cylindrical reflector  70  to strike LAD  15 . As the ever expanding light emerges in the direction of arrows  79 , some of it strikes and reflects off mirrored surface  71  of the concave reflector  70 . Mirrored surface  71  is mounted on a glass substrate  74 . The remaining light continues until it emerges at an angular extent that is determined by the parameters between the LAD  15  and mirrored reflector  71 . That is, altering the reflector&#39;s shape, size, focal point, length, curvature, etc., allows for obtaining any desired angular extent required. For example, the reflector&#39;s angular extent could be altered by cutting it off at marks  72  and  73 . Since the reflected light combines with the emerging light in the same plane, the emerging ring segment brightness is increased and made more uniform. Alternatively, a convex cylindrical reflector  78  shown in dotted lines may be employed to control the angular extent of the emerging light disc and function to give a wider angle of reflection. 
   Incorporating a LAD  15  on the optical axis of a concave, conical or parabolic reflector  80  having a slot (or hole) cut into its side is illustrated in  FIG. 9. A  laser beam  12  from laser  10  is directed through the slot striking LAD  15  producing a ring of light  17  that in turn strikes the inside of reflector  80 . The light ring is reflected and converged and then diverges, as shown by arrows  11 , to strike a polished surface  86  of cone  85  placed on an axis with the reflected beam. The ring of light after reflection from surface  86  of cone  85  is directed so as to be parallel to the ground, thereby enabling its use for level referencing purposes. With the structure fabricated within a bob, by its nature, the unit would be self leveling. 
   Other light altering devices may be constructed with monofilament fish line, single or multiple optical fibers, thin wires, or numerous other thin filament materials. These elements may be operated in vacuum, air, and be used in liquids, plastics, and glass and employed with or without cladding and/or covering materials. It is also contemplated that the cross sectional shapes of the aforementioned light altering devices may be altered for special purposes and that reflective coatings may also be applied to the light altering devices for special usages, for example, to improve emerging beam uniformity and efficiency. 
   It should now be understood that a low cost, radiant energy altering device has been disclosed that is a few millimeters in diameter and changes an input beam of radiant energy into an output in a disc pattern. The radiant energy altering device is low in cost and can comprise a variety of materials and geometries, including hollow glass tubes, fiber optic rods, tubes within tubes, etc. The altering device is not limited to input of laser energy, be it coherent or incoherent, multiple wavelength, i.e., broadband, colored or white, point or line source. 
   While the invention has been described in conjunction with the specific embodiments outlined above, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the preferred embodiments of the invention as set forth above are intended to be illustrative and not limiting. Various changes may be made without departing from the spirit and scope of the invention as defined herein.