Illumination system incorporating collimated light source

• US 20070127245A1
• Filed: 12/06/2005
• Published: 06/07/2007
• Est. Priority Date: 12/06/2005
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Magarill, Simon, Auerbach, Roy
• Granted Patent: US 7,411,735 B2
• Time in Patent Office: Days
• US Class Current: 362/291
• CPC Class Codes: G02B 27/0927 Systems for changing the beam intensity distribution, e.g. Gaussian to top-hat
• CPC Class Codes: G02B 27/0961 Lens arrays lens arrays per se G02B3/0006
• CPC Class Codes: G02B 27/0994 Fibers, light pipes optical fibers per se G02B6/02
• CPC Class Codes: G03B 21/2033 LED or laser light sources

Abstract

An optical system and a projection system incorporating same are disclosed. The optical system includes a light source that is capable of emitting light. The emitted light includes one or more substantially collimated discrete light beams. The optical system further includes a lenslet array for receiving and transmitting the emitted light. Each discrete light beam in the emitted light has an intensity full width at half maximum (FWHM) at the lenslet array that covers at least a portion of a plurality of lenslets in the lenslet array. The optical system further includes an optical element for receiving the transmitted light from an input face of the optical element. The optical element homogenizes the received light and transmits the homogenized light from an output face of the optical element.

Claims

1. An optical system comprising:

a light source capable of emitting light, the emitted light comprising one or more substantially collimated discrete light beams;

a lenslet array receiving and transmitting the emitted light, each discrete light beam in the emitted light having an intensity full width at half maximum (FWHM) at the lenslet array that covers at least a portion of a plurality of lenslets in the lenslet array; and

an optical element receiving the transmitted light from an input face of the optical element, the optical element homogenizing the received light and transmitting the homogenized light from an output face of the optical element.

2. The optical system of claim 1, wherein the light source comprises a laser light source.

3. The optical system of claim 1, wherein a half divergence angle of each substantially collimated discrete light beam is less than 2 degrees.

4. The optical system of claim 1, wherein a half divergence angle of each substantially collimated discrete light beam is less than 1 degree.

5. The optical system of claim 1, wherein the light source comprises one or more rows of discrete light sources.

6. The optical system of claim 1, wherein the light source comprises a two-dimensional array of discrete light sources.

7. The optical system of claim 1, wherein the light source comprises a three-dimensional array of discrete light sources.

8. The optical system of claim 1, wherein the FWHM of each discrete light beam at the lenslet array covers at least a portion of 4 lenslets.

9. The optical system of claim 1, wherein the FWHM of each discrete light beam at the lenslet array covers at least a portion of 7 lenslets.

10. The optical system of claim 1, wherein the FWHM of each discrete light beam at the lenslet array covers at least a portion of 9 lenslets.

11. The optical system of claim 1, wherein focal points of at least some of the lenslets in the lenslet array do not lie in a same plane.

12. The optical system of claim 1, wherein at least two lenslets in the lenslet array have different optical powers.

13. The optical system of claim 1 having an optical axis, wherein a shift of the lenslet array normal to the optical axis by half an outer diameter of a lenslet in the lenslet array changes a uniformity of the homogenized light by less than 5%.

14. The optical system of claim 1, wherein each lenslet has a hexagonal shape.

15. The optical system of claim 1, wherein each lenslet has a square shape.

16. The optical system of claim 1, wherein each lenslet has a rectangular shape.

17. The optical system of claim 1, wherein the lenslets in the lenslet array are closely packed.

18. The optical system of claim 1, wherein the lenslet array is an integral part of the optical element.

19. The optical system of claim 1, wherein the optical element homogenizes the received light by total internal reflection.

20. The optical system of claim 1, wherein the optical element is tapered.

21. The optical system of claim 1, wherein at least one of the input and output faces of the optical element is a rectangle.

22. The optical system of claim 1, wherein at least one of the input and output faces of the optical element is a square.

23. The optical system of claim 1, wherein at least one of the input and output faces of the optical element is a trapezoid.

24. A projection system comprising the optical system of claim 1.

25. An optical system comprising:

one or more light sources, each light source capable of emitting a substantially collimated light beam;

a lenslet array for receiving and expanding each substantially collimated light beam; and

an optical homogenizer for homogenizing light expanded by the lenslet array, wherein a ratio of an intensity full width at half maximum (FWHM) of each emitted substantially collimated light beam at the lenslet array to a lenslet outer diameter is at least 1.05.

26. The optical system of claim 25, wherein the ratio is at least 1.10.

27. The optical system of claim 25, wherein the ratio is at least 1.15.

28. The optical system of claim 25, wherein the lenslets in the lenslet array are closely packed.

29. The optical system of claim 25, wherein at least one of the one or more light sources is a laser light source.