Method and apparatus for modulating a light beam

• US 5,808,797 A
• Filed: 04/26/1996
• Issued: 09/15/1998
• Est. Priority Date: 04/28/1992
• Status: Expired due to Term

• Current Assignee: Silicon Light Machines Corporation (SCREEN Holdings Co., Ltd.)
• Original Assignee: Silicon Light Machines Corporation (SCREEN Holdings Co., Ltd.)
• Inventors: Bloom, David M., Sandejas, Francisco S. A., Solgaard, Olav
• Primary Examiner(s): Dzierzynski, Paul M.
• Assistant Examiner(s): Juba, Jr., John
• Application Number:
  US08/638,605
• Time in Patent Office: 872 Days
• Field of Search: 359/35, 359/573, 359/572, 349/86, 348/755, 345/31, 345/85, 345/108
• US Class Current: 359/572
• CPC Class Codes: B81B 3/001 Structures having a reduced contact area, e.g. with bumps or with a textured surface
• CPC Class Codes: B81C 2201/115 Roughening a surface
• CPC Class Codes: G02B 26/0808 by means of one or more diffracting elements
• CPC Class Codes: G02B 5/1828 having means for producing variable diffraction controlling the direction of light by means of one or more diffracting elements G02B26/0808; acousto-optical elements G02F1/11, G02F1/33; electro- or magneto-optical diffraction G02F1/292, G02F1/2955

Abstract

A modulator for modulating incident rays of light, the modulator having a plurality of equally spaced apart elements, each of which includes a light reflective planar surface. The elements are arranged parallel to each other with their light reflective surfaces parallel to each other. The modulator includes means for supporting elements in relation to one another and means for moving particular ones of the elements relative to others so that the moved elements transit between a first configuration wherein the modulator acts to reflect the incident rays of light as a plane mirror, and a second configuration wherein the modulator diffracts the light reflected therefrom. In operation, the light reflective surfaces of the elements remain parallel to each other in both the first and the second configurations. The perpendicular spacing between the reflective surfaces of respective elements is equal to m/4 times the wavelength of the incident rays of light, wherein m=an even whole number or zero when the elements are in the first configuration and m=an odd whole number when the elements are in the second configuration.

Claims

1. A light modulator configured for receiving a beam of multi-frequency light and for diffracting light having a composite of a subset of frequencies of the multi-frequency light in a predetermined direction, the modulator comprising at least two spatially separate sets of gratings each having a different grating period such that a first grating diffracts light of a first frequency of light from the multi-frequency light in the predetermined direction and the second grating diffracts light of a second frequency in the predetermined direction wherein the light diffracted by each set of gratings in the predetermined direction allows perception of a color which is intermediate to colors corresponding with the first and second frequencies.

2. The light modulator according to claim 1 wherein each set of gratings comprises:

a. a plurality of elongated elements, each including a light reflective planar surface, the elements being arranged parallel to each other and with the light reflective surfaces of the elements selectably lying in a single parallel plane and a plurality of parallel planes;

b. means for supporting the elements in a relation to one another such that the elements are spaced at a predetermined grating period; and

c. means for moving a first set of the elements in a direction normal to said planes and relative to a second set of the elements, and between a first configuration wherein said first and second sets of elements act to reflect the incident beam of light as a plane mirror, and a second configuration wherein said first and second sets of elements diffract the incident beam of light as it is reflected from the surfaces of the elements.

3. The light modulator according to claim 1, wherein each sets of the gratings reflects the beam of multi-frequency light as a plane mirror in a first configuration, and diffracts the beam of multi-frequency light in a second configuration.

4. A light modulator configured for receiving a beam of multi-frequency light and for diffracting light having a composite of a subset of frequencies of the multi-frequency light in a predetermined direction, the modulator comprising at least two spatially separate sets of gratings each having a different grating period such that a first grating diffracts light of a first frequency of light from the multi-frequency light in the predetermined direction and the second grating diffracts light of a second frequency in the predetermined direction wherein the light diffracted by each set of gratings is directed to the predetermined direction thereby allowing perception of a color which is intermediate to colors corresponding with the first and second frequencies.

5. The light modulator according to claim 4 wherein each grating set has a predetermined grating period, such that each grating period is selected to diffract light of a particular frequency in the predetermined direction.

6. The light modulator according to claim 5 further comprising an optical collection system configured to collect light diffracted from the grating sets.

7. A light modulator configured for receiving a beam of multi-frequency light and for diffracting light having a composite of a subset of frequencies of the multi-frequency light in a predetermined direction, the modulator comprising at least two spatially separate sets of gratings each having a different grating period such that a first grating diffracts light of a first frequency of light from the multi-frequency light in the predetermined direction and the second grating diffracts light of a second frequency in the predetermined direction and a diffraction control apparatus configured to control each of the sets of gratings to selectively diffract light wherein the light diffracted by each set of gratings in the predetermined direction allows perception of a color which is intermediate to colors corresponding with the first and second frequencies.

8. The light modulator according to claim 7 wherein each of the sets of gratings diffracts light in a first mode and reflects light in a second mode.

9. A color display system comprising:

a. a multi-frequency light source for forming a multi-frequency light beam;

b. a plurality of optical devices, each mounted to receive the light beam wherein each of the optical devices is selectably configurable to diffract a particular frequency of the light beam in a same predetermined direction for forming a plurality of diffracted beams; and

c. an optical collection system mounted to receive the diffracted beams for forming an image.

10. The color display system according to claim 9 wherein the light source generates white light.

11. The color display system according to claim 9 wherein the optical devices are configured to diffract a particular frequency of the light beam by each having a predetermined diffraction period selected to diffract the particular of light in the predetermined direction.

12. At least two modulators for modulating an incident beam of light, each comprising:

a. a plurality of elongated elements, each including a light reflective planar surface, the elements being arranged parallel to each other and with the light reflective surfaces of the elements lying in at least one parallel plane;

b. means for supporting the elements in a relation to one another such that the elements in each modulator are spaced at a predetermined grating period; and

c. means for moving a first set of the elements in a direction normal to said planes and relative to a second set of the elements, and between a first modulator configuration wherein said first and second sets act to reflect the incident beam of light as a plane mirror, and a second modulator configuration wherein said first and second sets diffract the incident beam of light as it is reflected from the surfaces of the elements wherein each modulator has a different grating period such that a first modulator diffracts a first frequency of light from the incident beam of light in a predetermined direction and a second modulator diffracts a second frequency of light from the incident light in the predetermined direction for allowing perception of a color which is intermediate to colors corresponding with the first and second frequencies.

13. A color display system comprising:

a. a multi-frequency light source for forming a multi-frequency light beam; and

b. at least two modulators for modulating an incident beam of light, each comprising;

(1) a plurality of elongated elements, each including a light reflective planar surface, the elements being arranged parallel to each other and with the light reflective surfaces of the elements lying in at least one parallel plane;

(2) means for supporting the elements in a relation to one another such that the elements in each modulator are spaced at a predetermined grating period; and

(3) means for moving a first set of the elements in a direction normal to said planes and relative to a second set of the elements, and between a first modulator configuration wherein said first and second sets act to reflect the incident beam of light as a plane mirror, and a second modulator configuration wherein said first and second sets diffract the incident beam of light as it is reflected from the surfaces of the elements

wherein each modulator has a different grating period such that a first modulator diffracts a first frequency of light from the incident beam of light in a predetermined direction and a second modulator diffracts a second frequency of light from the incident beam of light in the predetermined direction for allowing perception of a color which is intermediate to colors corresponding with the first and the second frequencies.

14. A device for modulating an incident beam of light for forming color, the incident beam including a plurality of frequencies, the device comprising:

a. a plurality of diffraction gratings; and

b. means for selectively configuring each grating to diffract the incident beam of light;

wherein each diffraction grating is configured to diffract a predetermined frequency of light in a same predetermined direction for spatially directing each predetermined frequency of light diffracted by each diffraction grating for allowing perception of color which is intermediate to colors of a frequency of light from each of the diffraction gratings.

15. The device according to claim 14 wherein each grating comprises a plurality of reflective elements arranged parallel to each other for reflecting the incident beam in a first configuration and diffracting the incident beam in a second configuration.

16. The device according to claim 15 wherein the means for selectively configuring comprises means for moving a first group of reflective elements relative to a second group of reflective elements such that the first group and the second group lie in a plurality of parallel planes.

17. The device according to claim 14 wherein each diffraction grating has a different grating period for diffracting a predetermined frequency of light in a predetermined direction.

18. A device for modulating an incident beam of light, the incident beam including a plurality of frequencies, the device comprising:

a. a first diffraction grating for diffracting light corresponding to a first frequency in a predetermined direction; and

b. a second diffraction grating for diffracting light corresponding to a second frequency in the predetermined direction, wherein the first frequency corresponds to a first color and the second frequency corresponds to a second color, further wherein the first and second frequencies are spatially directed to allow perception of a third color.

19. The device according to claim 18 further comprising a third diffraction grating for diffracting light corresponding to a third frequency in the predetermined direction.

20. The device according to claim 19 wherein the first frequency corresponds to red light, the second frequency corresponds to green light and the third frequency corresponds to blue light.

21. The device according to claim 18 wherein the first and second diffraction gratings are independently configurable to diffract light.

22. The device according to claim 18 further comprising a plurality of additional display elements for forming a display image.