OPTICAL UNIT, LIGHT PROCESSING UNIT, LIGHT PROCESSING METHOD, ILLUMINATION UNIT AND IMAGE GENERATION UNIT

Abstract

For displaying a color image by recombination of several single color images, parasitic noise like speckles due to scattering within the system, in particular when laser light is involved, with the invention a significant improvement with a low number of parts can be realized by use of a color wheel that comprises in radially divided zones refractive elements for redirecting light beams incoming at different impinging angles and redistributing elements, e.g. a hologram, that provide for a defined output beam in an optical axis. The sequence of the individual light processing zones on the color wheel are synchronized with respective laser sources. The invention combines the functionality of plural elements, reduces speckles and avoids losses.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The invention and advantageous features thereof will be explained with reference to preferred embodiments and with reference to the accompanying drawings in which

FIG. 1 is a schematic and cross-sectional view of a first embodiment of the light processing optical unit consisting of a colour wheel according to the present invention;

FIG. 2 is a schematic and cross-sectionally enlarged side view of a zone of the colour wheel of FIG. 1;

FIGS. 3A to C elucidate by means of schematic and cross-sectional side views the working principle of an embodiment of a light processing optical unit with a colour wheel according to the present invention;

FIGS. 4A, B are schematic and cross-sectional side views which elucidate an aspect of a further embodiment of the light processing optical unit according to the present invention designed to diffuse and redistribute light energy uniformly;

FIGS. 5A to C

FIGS. 6A to C and

FIGS. 7A to C elucidate by means of schematic and cross-sectional side views varieties of the working principle of a colour wheel provided according to an advantageous embodiment of the invention with a surface structure for generating a controlled refraction index, reshaping and redistributing;

FIGS. 8 to 10 are schematic and cross-sectional side views of an arrangement of optical and electrooptical components including a colour wheel elucidating aspects of various embodiments of an image generation unit according to the invention;

FIG. 11 is a schematic and cross-sectional side view of a colour wheel according to the present invention on which light beams impinge at different angles of incidence;

FIGS. 12 to 15B elucidate parasitic optical noise and speckle reduction properties of embodiments of light processing optical units according to the present invention; and

FIG. 16 is a schematic and cross-sectional side view of a further embodiment of an image generation unit according to the present invention.

Claims

1. Optical unit, comprising: one or a plurality of light sources (Sk, k=1, . . . , M),a wheel which modifies the direction and shape properties of the light incident on it and whose rotation is achieved in a controlled manner by electro-mechanical means,a device monitoring the rotation of the wheel and modulating the sources depending of the rotational position of the wheel or modifying the rotation of the wheel.

2. Optical unit according to claim 1, wherein said wheel consists of a front face and a back face whose surfaces are structured.

3. Optical unit according to any one of the preceding claims, wherein any one of the structures consists of combinations of diffractive means, refractive means or diffusing means with structures larger or smaller than the wavelength of the light and maybe sensitive to polarization of the light.

4. Optical unit according to any one of the preceding claims, wherein the space comprised between the front face and the back face of the wheel is structured in volume, as a variation of the complex refraction index, that is a variation of index of refraction, reflectivity and absorption.

5. Optical unit according to any one of the preceding claims, wherein the front face or the back face is covered with a reflecting material or structure.

6. Optical unit according to any one of the preceding claims, wherein the structuring of the wheel deflects and shapes the light so the distribution of light after interaction with the wheel presents a defined angular distribution of light power.

7. Optical unit according to any one of the preceding claims, wherein any of the light sources contains lasers.

8. Optical unit according to any one of the preceding claims, wherein any of the light sources contains several emitters.

9. Optical unit according to any one of the preceding claims, wherein any of the light sources contains primary optics for collimation of the emitted light and redirection onto the wheel.

10. Optical unit according to any one of the preceding claims, where the light emitted by the sources converge towards a defined locus, and part of the wheel is located at that locus.

11. Optical unit according to any one of the preceding claims, wherein the wheel is divided into N zones (Zj, j=1, . . . ,N).

12. Optical unit according to any one of the preceding claims, wherein the zones are shaped as sectors or annular segments of sectors.

13. Optical unit according to any one of the preceding claims, wherein the synchronization of the sources with respect to the wheel position is realized so that, at any instant, only the sources members of one group Sk emit light falling on the wheel. No more than one group Sk can be emitting light when the zone Zj is in the area B.

14. Light processing unit comprising a transparent color wheel (W) to be rotated around an axis (RZ) and having a front face (Wa) and a back face (Wb), at least one of said faces being provided with a microstructure on said respective face designed to deflect, diffuse and redistribute light impinging on said front face (Wa) uniformly such that light beams exiting said back face are oriented along an optical axis (OZ).

15. Light processing unit of claim 14, wherein said color wheel (W) contains at least three distinct radially equidistant zones (Zj), each zone being assigned to a narrow-band light source (Sj), and wherein the rotation speed of drive for said color wheel is synchronized with switching means for sequentially switching on/off the light sources only when the respective light source beam area impinges on the associated zone on said color wheel.

16. Light processing unit of claim 14, wherein the front face zones of said color wheel are structured with sets of refractive elements (MS), each set being assigned to one zone, the deflection angle of each set of said refractive elements being selected to counter the incident angle of the beam of the corresponding light source (Sj) such that the light incident on and emanating from the back face of the color wheel is parallel to the optical axis (OZ), and wherein the back face of the color wheel is provided with a hologram that redistributes the impinging light within a homogeneous pyramidal exit beam.

17. Light processing unit of claim 16, wherein the front face zones of the color wheel are provided with a hologram that distributes the beam of the corresponding light source (Sj) within a pyramidal beam of defined angles with respect to the incident beam direction, and wherein the back face of the color wheel is structured with sets of refractive elements, each set being assigned to one zone, the deflection angle of each set of said refractive elements being selected to counter the incident angle of the beam of the corresponding light source (Sj).

18. Light processing unit of claim 15, wherein one of said front and back faces of said color wheel is patterned with a hologram that combines the function of redirecting the beam of the front face incident light such that the light emanating from the back face is parallel to the optical axis with the function of shaping said exiting light beam to be distributed within a homogeneous pyramidal beam.

19. Light processing unit of claim 15, wherein said front face zones or said back face zones are structured with sets of refractive elements, each set being assigned to one zone, the deflection angle of each set of said refractive elements being selected to deflect the incoming light toward the optical axis (OZ), and wherein said back face zones or said front face zones, respectively, are patterned with a hologram that combines the function of redirecting the beam emanating said refractive micro-prism to bring it in line with the optical axis with the function of shaping said light beam to be distributed within a homogeneous pyramidal beam.

20. Light processing unit of at least one of claims 17 to 19, wherein said hologram is a computer-generated hologram.

21. Light processing unit of at least one of claims 16 to 19, wherein said refractive elements are sets of micro-prisms.

22. Light processing unit of at least one of claims 16 to 19, wherein the dimensional structure of said refractive elements are smaller than the wavelength of the light impinging on said color wheel.

23. Light processing unit comprising: a light entrance section (E) for receiving primary illumination light (L1),a light processing section (P) for processing said received primary light (L1) and for outputting secondary illumination light (L2),a light output section (O) providing said secondary light (L2),wherein said light processing section (P) comprises a color wheel (W) which is adapted to and comprises means for receiving, redistributing and/or redirecting said primary illumination light (L1) to thereby generating said processed illumination light (L1) as said secondary illumination light (L2) which is redistributed and/or redirected compared to said primary illumination light (L1).

24. Light processing unit of claim 23, wherein said color wheel (W) comprises a front face (Wa) for receiving said primary illumination light (L1) and wherein said color wheel (W) comprises a back face (Wb) for emitting said secondary illumination light (L2).

25. Light processing unit of claim 23, wherein said means for reshaping, redistributing and/or redirecting said primary illumination light (L1) are formed as at least one zone (Zj; j=1, 2, 3) of said color wheel element (W).

26. Light processing unit of claim 25, wherein said zone (Zj; j=1, 2, 3) of said color wheel is formed as a sector, a segment or a segmented ring of said color wheel.

27. Light processing unit of claim 26, wherein said zone of said color wheel comprises means for receiving as said primary illumination light (L1) in a defined spectral range and a defined light entrance direction (e).

28. Light processing unit of claim 25, wherein said zone of said color wheel comprises means for emitting as said secondary illumination light (L2) a defined spectral range to a defined light output direction (o).

29. Light processing unit of claim 25, wherein in the case of a plurality of zones of said color wheel said respective light output directions (o) are identical and coincide to a common optical axis (Z).

30. Light processing unit of claim 29, wherein said color wheel is rotatable about a rotational axis (RZ) and wherein said common optical axis (Z) of said plurality of zones of said color wheel element is defined by an inclination angle with respect to said rotational axis (RZ) of said color wheel.

31. Light processing unit of claim 30, wherein said common optical axis (Z) of said plurality of zones of said color wheel are parallel with respect to said rotation axis of said color wheel.

32. Light processing unit of claim 29, wherein said zones of said color wheel comprise deflection means in or on said front face (Wa) of said color wheel.

33. Light processing unit of claim 32, wherein said zones of said color wheel comprise deflecting means in or on said back face (Wb) of said color wheel.

34. Light processing unit of claim 33, wherein said deflecting means are adapted to deflecting and redirecting said primary illumination light from said light entrance direction completely to said light output direction.

35. The light processing unit of claim 29, wherein said zones comprise first deflecting means in or on said front face of said color wheel,said zones comprise second deflecting means in or on said back face of said color wheel,said first deflecting means is adapted to deflecting and redirecting said primary illumination light from said light entrance direction into defined intermediate light propagation direction, and whereinsaid second deflecting means is adapted to redirecting said intermediate redirected illumination light (L1) from said intermediate light propagation direction completely into said desired light output direction.

36. Light processing unit according to any one of the preceding claims 32 to 34, wherein said deflecting means are provided on one out of the group consisting of diffracting means, refracting means, grating structures and micro-prisms arrangements.

37. Light processing unit of claim 29, wherein said zones of said color wheel comprise first reshaping and redistributing means in or on said front face of said color wheel, wherein said zones of said color wheel element comprise second reshaping and redistributing means in or on said back face of said color wheel,wherein said first reshaping and redistributing means is adapted to reshaping and redistributing said primary illumination light from a given entrance distribution into a defined intermediate distribution, andwherein said second reshaping and redistributing means is adapted to reshaping and redistributing said intermediate reshaping and redistributing primary illumination light from said intermediate distribution into a desired output distribution.

38. Light processing unit of claim 31, wherein said reshaping and redistributing means are provided as one of the group consisting of diffracting means, grating structures and hologram structures.

39. Light processing unit of claim 38, wherein said zones are adapted in order to reduce parasitic optical noise or speckles by optical diffusion properties as part of said reshaping and redistributing means.

40. Illumination unit comprising a light source unit (20) for generating and providing a primary light (L1),a light processing or optical unit (10) according to at least one of the preceding claims for receiving said primary light (L1) and for generating and providing processed primary light (L1′) as secondary light (L2), which secondary light is redistributed and redirected compared to said primary light (L1).

41. Illumination unit according to claim 40, wherein a plurality of light sources is provided in said light source unit, and wherein each of said light sources is assigned to one zone of said color wheel.

42. Illumination unit according to claim 41, wherein said light sources are operable in geometrical synchronization with respectively assigned zones of the rotated color wheel in order to illuminate by an associated light source the respectively assigned zone at a respectively assigned time slid only.

43. Illumination unit according to claim 42, wherein said light sources are coherent light sources.

44. Illumination unit according to claim 43, wherein said coherent light sources are laser light sources.

45. The illumination unit according to claim 42 comprising condenser optics (40) including means (RO) for receiving said secondary light (L2) from said light processing optical unit and for generating and providing condensed secondary light (L2′) as tertiary illumination light (L3).

46. An image generation unit comprising an illumination unit (1) according to at least one of the preceding claims 40 to 45, andan image modulator unit (100′) adapted and comprising means (100) for receiving said tertiary light (L3) and for providing output light (L4) which is representative for an image (I).

47. Light processing method, wherein a transparent color wheel (W) having a front face (Wa) and a back face (Wb), at least one of said faces being provided with a microstructure on said respective face designed to deflect, diffuse and redistribute light impinging on said front face (Wa) uniformly such that light beams exiting said back face are oriented along an optical axis (OZ), is used and rotated around an axis (RZ).

48. Light processing method according to claim 47, wherein light is impinged on said front face (Wa) and thereby deflected, diffused and redistributed.

49. Light processing method according to any one of the preceding claims 47 and 48, wherein at least three narrow-band light sources (Sj) are assigned to respective distinct radially equidistant zones contained in said color wheel (W),

50. Light processing method according to claim 49, wherein the rotation speed for said color wheel (W) is synchronized with switching means for sequentially switching on of the light sources (Sj) only when the respective light source beam area impinges on the associated zone on said color wheel (W).

51. Light processing method according to any one of the preceding claims 47 to 50, wherein an incident angle of a beam of a light source (Sj) is countered by having accordingly selected a deflection angle of a respective set of said refractive elements of a respective assigned front face zone andsuch that the light incident on the back face of the color wheel (W) is thereby directed parallel to the optical axis (OZ).

52. Light processing method according to claim 51, wherein the impinging light is redistributed within a homogeneous pyramidal exit beam by employing a hologram at the back face (Wb) of the color wheel (W).

53. Light processing method according to any one of the preceding claims 47 to 50, wherein the beam of a corresponding light source (Sj) is distributed within a pyramidal beam of defined angles with respect to the incident beam direction with a hologram at the front face zones of the color wheel (W),

54. Light processing method according to claim 53, wherein the incident angle of the beam of the corresponding light source (Sj) is countered having accordingly selected the deflection angle of a respective set of said refractive elements at the back face of the color wheel (W), each set being assigned to one zone (Zj).

55. Light processing method according to any one of the preceding claims 47 to 50, wherein a beam of the front face incident light redirected and redistributed with a hologram patterned on one of said front and back faces (Wa, Wb) of said color wheel (W) that combines the function of redirecting the beam of the front face incident light such that the light emanating from the back face is parallel to the optical axis with the function of shaping said exiting light beam to be distributed within a homogeneous pyramidal beam.

56. Light processing method according to any one of the preceding claims 47 to 50, wherein incoming light is deflected the toward the optical axis (OZ) with sets of refractive elements structured on said front face zones or said back face zones, each set being assigned to one zone, the deflection angle of each set of said refractive elements being accordingly selected.

57. Light processing method according to claim 50, wherein the beam emanating said refractive micro-prism is redirected in line with the optical axis and distributed within a homogeneous pyramidal beam with a hologram patterned on said back face zones or said front face zones, respectively, that combines the function of redirecting to bring it with the function of shaping said light beam.