Direct optical image projectors

• US 7,440,158 B2
• Filed: 03/02/2007
• Issued: 10/21/2008
• Est. Priority Date: 03/02/2007
• Status: Active Grant

• Current Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Ryf, Roland, Lopez, Omar Daniel, Giles, Randy Clinton
• Primary Examiner(s): Ben; Loha
• Application Number:
  US11/713,207
• Publication Number:
  US 20080212159A1
• Time in Patent Office: 599 Days
• Field of Search: 359/237, 359/238, 359/245, 359/263, 359/276, 359/290, 359/291, 359/298, 359/279, 359/308, 359/559, 359/560, 359/562, 359/563, 349/104, 349128-130, 353/20, 353/31, 353/85, 353/97, 356/124, 356/124.5, 356/310, 356/326, 356/328, 356/330, 250/550, 250/559.42, 708/816
• US Class Current: 359/279
• CPC Class Codes: G02B 26/06 for controlling the phase of light G02B26/08 takes precedence , measuring optical phase difference G01J9/00
• CPC Class Codes: G02B 27/46 Systems using spatial filters
• CPC Class Codes: G02B 27/48 Laser speckle optics
• CPC Class Codes: G03B 33/06 by additive-colour projection apparatus
• CPC Class Codes: G03H 1/08 Synthesising holograms, i.e. holograms synthesized from objects or objects from hologramsusing electric digital computers G06F; G06T
• CPC Class Codes: G03H 1/2294 Addressing the hologram to an active spatial light modulator
• CPC Class Codes: G03H 1/32 Systems for obtaining speckle elimination
• CPC Class Codes: G03H 2001/0816 Iterative algorithms
• CPC Class Codes: G03H 2001/0858 Cell encoding wherein each computed values is represented by at least two pixels of the modulator, e.g. detour phase coding
• CPC Class Codes: G03H 2001/221 Element having optical power, e.g. field lens
• CPC Class Codes: G03H 2001/2218 being perpendicular to optical axis
• CPC Class Codes: G03H 2001/2271 RGB holobject
• CPC Class Codes: G03H 2222/18 RGB trichrome light
• CPC Class Codes: G03H 2222/54 Convergent beam
• CPC Class Codes: G03H 2225/24 Having movable pixels, e.g. microelectromechanical systems [MEMS]
• CPC Class Codes: G03H 2225/32 Phase only
• CPC Class Codes: G03H 2227/03 Means for moving one component G03H1/0476, G03H2001/2695 take precedence

Abstract

An apparatus includes a reconfigurable spatial light modulator, a light source, and a transmission filter. The reconfigurable spatial light modulator is capable of producing spatially varying amplitude and/or phase modulations of an incident light wavefront. The light source is configured to direct an illumination light beam towards the reconfigurable spatial light modulator such that the modulator produces a modulated outgoing light beam there from. The transmission filter is configured to spatially filter a light pattern formed by the outgoing light beam and to selectively transmit light from substantially only one diffractive order of the light pattern.

Claims

1. An apparatus, comprising:

a reconfigurable spatial light modulator capable of producing spatially varying amplitude and/or phase modulations of an incident light wavefront;

a light source being configured to direct an illumination light beam towards the reconfigurable spatial light modulator such that the modulator produces a modulated outgoing light beam; and

a transmission filter being configured to spatially filter a light pattern formed by the outgoing light beam and to selectively transmit light from substantially only one diffractive order of the light pattern.

2. The apparatus of claim 1, wherein the reconfigurable spatial light modulator is configured to modulate a phase of the incident light wavefront.

3. The apparatus of claim 1, further comprising:

a lens system being configured to cause the illumination light beam to be converging at the reconfigurable spatial light modulator.

4. The apparatus of claim 1, wherein the modulator includes a reconfigurable array of mirrors and an array of MEMS actuators, at least some of the mirrors being moveable, each of the MEMS actuators being configured to control translations of a corresponding one of the moveable mirrors.

5. The apparatus of claim 4, further comprising:

a lens system being configured to cause the outgoing light beam to focus such that the light pattern is able to form where the outgoing beam is focused.

6. The apparatus of claim 5, wherein the light source comprises a plurality of coherent sources, each coherent source being configured to emit light of a different color than the remaining of the coherent sources.

7. The apparatus of claim 6, wherein the light source is configured to illuminate the mirrors with a time division color-multiplexed light beam.

8. The apparatus of claim 1, wherein the reconfigurable spatial light modulator includes a reconfigurable array of birefringent liquid crystal cells, the optical axes of individual ones of the cells being rotatable responsive to electrical control signals applied thereto.

9. The apparatus of claim 8, further comprising:

a lens system being configured to cause the outgoing light beam to focus such that the light pattern is able to form where the outgoing beam is focused.

10. The apparatus of claim 8, wherein the light source comprises a plurality of coherent sources, each coherent source being configured to emit light of a different color than the remaining of the coherent sources.

11. The apparatus of claim 10, wherein the light source is configured to illuminate the modulator with a time division color-multiplexed light beam.

12. A method, comprising:

modulating a wavefront of an incident coherent light beam to produce an outgoing light beam having spatial variations on wavefronts thereof;

focusing a light beam such that the outgoing light beam can form a diffractive light pattern that is approximately a Fourier transform of the modulated wavefront;

spatially filtering the diffractive light pattern to transmit light of substantially only one diffractive order therein;

projecting the transmitted light onto a viewing screen to produce an image.

13. The method of claim 12, wherein the spatially filtering transmits light of substantially only one bright spot of the diffractive light pattern.

14. The method of claim 13, wherein the only one bright spot is in the zeroth diffractive order of the diffractive light pattern.

15. The method of claim 13, wherein the modulating causes a phase modulation of the wavefront.

16. The method of claim 12, wherein the modulating causes a phase modulation of the wavefront.

17. The method of claim 12, wherein the focusing causes the incident coherent light beam to be convergent at a modulator that performs the modulating.

18. The method of claim 12, further comprising repeating the modulating, focusing, spatially filtering, and projecting for incident light beam of a different color.