Optical device, system and method
Methods and systems are disclosed related to optical elements. An apparatus for making an optical device can be configured to divide an angular pattern into a plurality of sub-angular regions. Then, micro-wedge configurations can be determined for directing light to the sub-angular regions. Subsequently, an array of micro-wedges can be generated according to the micro-wedge configurations, such that adjacent micro-wedges in the array have different configurations.
This application claims priority under 35 U.S.C. § 120 on and is a Continuation of U.S. patent application Ser. No. 09/507,466 entitled “OPTICAL DEVICE, SYSTEM AND METHOD” filed on Feb. 22, 2000, which is incorporated herein by reference in its entirety.
FIELD OF THE INVENTIONThe present invention relates generally to optics and optical systems and devices. The present invention also relates to a device for forming an homogenized light pattern. The present invention also relates to a method of making an optical device.
BACKGROUND OF THE INVENTIONKnown techniques for homogenizing light make use of arrayed micro-lenses, diffractive diffusers, ground glass diffusers, and holographically-generated diffusers. Micro-lens arrays homogenize light by creating an array of overlapping diverging cones of light. Each cone originates from a respective micro-lens and diverges beyond the focal spot of the lens. In the known arrays, the individual lenses are identical to each other. Ground glass diffusers are formed by grinding glass with an abrasive material to generate a light-scattering structure in the glass surface.
Micro-lens arrays, ground glass diffusers and holographic diffusers all have the disadvantage of not being able to control the angular spread of the homogenized, diverging light. Light in general has an angular spread that is fairly uniform over a desired angular region, but the boundaries of the angular region are blurred. With the known diffuser methods, the energy roll-off at the edge of the desired angular spread can extend well beyond this region.
Diffractive diffusers can be used to control the angular spread of the output light, but such diffusers are limited with respect to the amount of spread that they can impart to the output light. Due to fabrication limitations for short wavelength sources, visible or below, and limitations in the physics of the structures for longer wavelengths the maximum angular spread is limited. Further, diffractive diffusers used in their traditional binary form can include a significant amount of background energy and the patterns must be symmetric about the optical axis.
Thus, there is a need for a device which can homogenize light while controlling a broad angular spread of the homogenized, diverging light beam. Additionally, there is a need for a method of making an improved device for homogenizing light.
SUMMARY OF THE INVENTIONThe disadvantages of the prior art are overcome to a great extent by the present invention. The present invention relates to an optical device formed of a plurality of optical elements. The elements may be used to direct portions of an incident light beam in predetermined, respective directions. The optical elements may be formed adjacent to each other in a two-dimensional array. Adjacent elements may have different shapes. The locations of the elements in the array may be essentially random with respect to the directions of the corresponding light beam portions.
According to preferred embodiments of the invention, the optical elements may be formed of transparent or reflective materials. The output surfaces of the respective elements may be flat and planar or they may be curved and non-planar.
According to another aspect of the invention, the optical device may be used to form an angular pattern. Alternatively, the device may be used to split the incoming beam into sub-beams.
The present invention also relates to an optical system that has a light source and an optical homogenizing device. The optical device may be formed of a large number of micro-wedges. The wedges may be used to form respective non-adjacent portions of a desired angular pattern. In a preferred embodiment of the invention, adjacent wedges may be formed with different three-dimensional conjurations.
The present invention also relates to a method of making a multi-faceted optical device. The method includes the steps of (1) dividing an angular pattern into sub-angular regions, (2) determining micro-wedge configurations for directing beam portions to the sub-angular regions, and (3) generating an array of micro-wedges, according to the determined configurations, such that adjacent wedges have different configurations.
According to another aspect of the invention, the two-dimensional arrangement or ordering of the wedges in the device-array is essentially random with respect to the two-dimensional arrangement of the sub-angular regions in the pattern. According to this aspect of the invention, the respective micro-wedge configurations may be assigned to random locations in the array. Thus, the relative positions or order of the wedges in the array has essentially no relationship to the relative positions or order of the sub-angular regions in the pattern. According to yet another aspect of the invention, the output surface slopes for the micro-wedges are calculated by a programmed general-purpose computer based on the locations of the respective sub-angular regions in the desired pattern.
In a preferred embodiment of the invention, appropriate phase tare surfaces may be used to divide the output surfaces of the micro-wedges into stepped or terraced surfaces, to thereby reduce the overall thickness of the optical device.
According to yet another aspect of the invention, an optical homogenizing device is formed of a tiled array of sub-devices, where each sub-device has randomly arranged micro-wedges. The tiled device may be used, for example, to handle large diameter input beams.
Thus, the present invention provides a method and apparatus for homogenizing a beam of light. The invention makes use of micro-structures in an array where each optical element or micro-wedge is different from its adjacent neighbor in size and slope. The array of different micro-wedges can homogenize light sources without the disadvantages of the prior art. Various combinations and alterations to the micro-wedge array may include: adding a phase bias to the micro-wedges to further scramble the incoming beam; and adding a lens function to the surface of the array or to the back surface of the device.
The present invention may be used to homogenize light sources, perform beam splitting operations, and/or to redirect light in a given direction.
These and other advantages and features of the invention will become apparent from the following detailed description of the invention which is provided in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Referring now to the drawings, where like reference numerals designate like elements, there is shown in
In a preferred embodiment of the invention, the optical device 16 is formed of an array of optical wedges 22, 24. The wedges 22, 24 receive incident portions of the input beam 14 and direct the beam portions 46, 48 toward respective portions 50, 52 of the angular pattern 18.
As shown in more detail in
In a preferred embodiment of the invention, the areas of adjacent wedges 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44 are made unequal by selecting the lengths of the edges 142 appropriately. As shown in
The arrows 60 in
Phase tare surfaces 70, 72, 74, 76, 78, 80, 82, 84 may be provided to reduce the overall thickness of the optical device 16. Thus, the first wedge 22 is separated by a tare surface 70 into first and second portions 90, 92. The slopes (60) of the first and second portions 90, 92 may be equal to each other. That is, the planar output surfaces of the first and second portions 90, 92 may be parallel to each other. Likewise, the second wedge 24 is separated by a tare surface 72 into first and second parallel portions 94, 96. The slopes (designated by arrows 60) of the two portion 94, 96 may be equal to each other.
The tare surfaces 70, 72, 74, 76, 78, 80, 82, 84 in effect operate to fold the output surfaces of the micro-wedges 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44. The tare surfaces 70, 72, 74, 76, 78, 80, 82, 84 may be especially useful when the slopes (60) of the wedge output surfaces are relatively great. The heights of the tare surfaces 70, 72, 74, 76, 78, 80, 82, 84 (measured in the direction from top to bottom as viewed in
As shown in
In operation, the light source 12 transmits the input beam 14 toward the optical device 16. The input beam 14 may have an uneven intensity distribution across its cross section. The beam 14 is directed onto the optical device 16 such that portions of the beam 14 are incident on respective wedges 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44. The wedges 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44 direct the beam portions 46, 48 in predetermined directions to form an homogenized angular pattern 18. The homogenized pattern 18 may have a substantially uniform light intensity distribution. The beam portions 46, 48 are transmitted in different directions since each wedge 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44 is different from its adjacent and neighboring wedges 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44 in size and/or slope (60). Thus, the light output 46, 48 of each wedge 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44 is directed or angled toward a particular sub-angular region 50, 52 of the desired angular spread 18. Although the angular spread or pattern 18 is shown as the letter “H” in
Referring now to
Then, using appropriate geometric calculations, a slope and a three dimensional configuration for each wedge is determined such that the wedge will direct a portion of the input beam to a respective sub-angular region (Step 152). Then, a location within the device 16 is randomly chosen for each calculated wedge configuration (Step 154). The random placement of the wedges 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44 in the optical device 16 causes the pattern 18 to have a uniform intensity. In other words, the random location of the wedges 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44 causes the input beam 14 to be homogenized.
The output surfaces of the wedges 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44 may then be formed in a suitable substrate (e.g., glass) by gray scale photolithography, a suitable direct write method (e.g., electron beam or laser), or by another suitable technique (Step 156).
If the number of sub-angular regions in the pattern 18 is less than the number of micro-wedges desired to be arrayed in the device 16, then some of the wedges may have the same slope and size. The similar wedges will direct light energy to the same location or sub-angular region. However, the wedges with similar slopes, sizes and shapes are preferably not located adjacent one another.
The illustrated optical device 16 may be used to increase the amount of angular spread in the pattern 18 while maintaining a well defined pattern boundary 158 (
In addition, the device 16 may be used efficiently over a broad wavelength band, including but not limited to white light. This is an advantage over diffractive diffusers since diffractive diffusers are tuned to a particular wavelength and have decreased efficiency at different wavelengths.
According to another embodiment of the invention, an optical device 100 (
For certain desired angular regions, the number of sub-angular regions required to fill the region can be very large (for example, greater than ten thousand) which requires a very large number of micro-wedges. In these instances, the input beam 14 should have a small diameter to illuminate all portions of the tiles 16. By decreasing the size of the individual micro-wedges, the input beam size can be reduced. The size of the wedges 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44 preferably should not be so small, however, as to cause the diffraction angle defined by the wedge apertures to become too great.
As shown in
The present invention may also be employed with a phase bias device or an optical lens 140 as shown schematically in
According to yet another aspect of the invention, the facet boundaries 142 (
Reference has been made to preferred embodiments in describing the invention. However, additions, deletions, substitutions, or other modifications which would fall within the scope of the invention defined in the claims may be implemented by those skilled in the art without departing from the spirit or scope of the invention. Accordingly, the invention is not to be considered as limited by the foregoing description, but is only limited by the scope of the appended claims.
Claims
1. An apparatus for making an optical device comprising:
- means for dividing an angular pattern into a plurality of sub-angular regions;
- means for determining micro-wedge configurations for directing light to said sub-angular regions; and
- means for subsequently, generating an array of micro-wedges according to said micro-wedge configurations, such that adjacent micro-wedges in said array have different configurations.
2. The apparatus of claim 1, wherein the two-dimensional arrangement of said micro-wedges in said array is essentially random with respect to the two-dimensional arrangement of said sub-angular regions of said pattern.
3. The apparatus of claim 2, further comprising
- means for assigning said micro-wedge configurations to random locations in said array.
4. The apparatus of claim 3, wherein means for determining micro-wedge configurations includes means for calculating output surface slopes for said micro-wedges.
5. The apparatus of claim 1, wherein said means for generating said array a means for forming phase tare surfaces in said micro-wedges.
6. The apparatus of claim 1, wherein said means for generating includes means for forming output surfaces for said micro-wedges.
7. The apparatus of claim 1, further comprising:
- means for providing a plurality of tiles of said micro-wedge arrays.
8. An optical device, comprising:
- a substrate, the substrate adjacent to a medium, the substrate comprising: a smooth regularly shaped exterior surface; and an irregularly shaped exterior output surface, said irregularly shaped exterior output surface comprising: a first optical element for directing a first portion of an incident light beam exiting the irregularly shaped exterior output surface via the first optical element in a predetermined first direction; and a second optical element, adjacent to said first optical element on the irregularly shaped exterior surface and formed on a same side of said irregularly shaped exterior output surface as said first optical element, for directing a second portion of said incident light beam exiting the irregularly shaped exterior output surface via the second optical element in a predetermined second direction in the medium different from said predetermined first direction in the medium, the light beam exiting in the first and second directions contributing to a portion of a predetermined pattern;
- wherein said first optical element is of a first shape, said second optical element is of a second shape different from said first shape, said first and second shapes are microwedges, and said first optical element and said second optical element have non-textured and substantially planar output surfaces.
9. The device of claim 8, wherein said first and second optical elements are transparent.
10. The device of claim 8, wherein said first and second optical elements are reflective.
11. The device of claim 8, further comprising a lens for performing a Fourier transform operation.
12. The device of claim 8, further comprising a device for optically modifying said incident light beam.
13. The device of claim 8, wherein said optical elements are arranged to split the incident light beam.
14. An optical device, comprising:
- a substrate comprising: a first smoothly regular surface; and a second surface, wherein the second surface has at least two portions, a first portion and a second portion, the first portion has a first portion surface and the second portion has a second portion surface, the first and second portion surfaces being adjacent and non-continuous, the first portion for directing a first light beam exiting the first portion in a predetermined first direction, and the second portion for directing a second light beam exiting the second portion in a predetermined second direction, the first light beam and second light beam contributing to a portion of a predetermined pattern.
15. The device of claim 14, wherein the first smoothly regular surface is flat.
16. The device of claim 14, wherein the first portion surface is curved.
17. The device of claim 14, wherein the first portion surface is parabolic.
Type: Application
Filed: Dec 19, 2005
Publication Date: Sep 27, 2007
Inventor: David Brown (Meridianville, AL)
Application Number: 11/305,325
International Classification: G02B 27/46 (20060101);