Image projection screen with reduced speckle noise

1. An arrangement for projecting an image with reduced speckle noise, comprising:

a) a display screen having front and rear surfaces, and an array of lenslets;

b) an image projection assembly for directing a laser beam on the rear surface of the screen, and for sweeping the beam as a pattern of scan lines across the rear surface of the screen, each scan line extending along a scan direction and having a number of pixels, and for causing selected pixels to be illuminated, and rendered visible, to produce the image, the laser beam having a beam dimension along the scan direction; and

c) means for reducing speckle noise by configuring each lenslet to have a lenslet dimension, as measured along the scan direction, which is not less than said beam dimension.

2. The arrangement of claim 1 , wherein the assembly includes a laser for emitting the laser beam.

3. The arrangement of claim 2 , wherein the laser is one of a red, blue and green laser.

4. The arrangement of claim 1 , wherein the lenslet dimension is larger than said beam dimension.

5. The arrangement of claim 1 , wherein the lenslets are successively arranged along the scan direction; and a polarization rotating coating on alternate lenslets.

6. The arrangement of claim 4 , wherein each lenslet has a spherical curvature.

7. The arrangement of claim 1 ; and an apertured mask at an image plane of the array of lenslets.

8. The arrangement of claim 7 , wherein the mask absorbs the laser beam incident thereon.

9. A method of projecting an image with reduced speckle noise, comprising the steps of:

a) emitting a laser beam;

b) directing the beam to be incident on a rear surface of a display screen, and sweeping the beam as a pattern of scan lines across the rear surface of the screen, each scan line extending along a scan direction and having a number of pixels, and causing selected pixels to be illuminated, and rendered visible, to produce the image, the laser beam having a beam dimension along the scan direction; and

c) forming the screen with an array of lenslets, and configuring each lenslet to have a lenslet dimension, as considered along the scan direction, which is not less than said beam dimension, thereby reducing speckle noise.

10. The method of claim 9 , wherein the emitting step is performed by one of a red, blue and green laser.

11. The method of claim 9 , wherein the lenslet dimension is larger than the beam dimension.

12. The method of claim 9 , and arranging the lenslets in succession along the scan direction; and applying a polarization rotating coating on alternate lenslets.

13. The method of claim 9 , wherein each lenslet has a spherical curvature.

14. The method of claim 9 , and positioning an apertured mask at an image plane of the array of lenslets.

15. A display screen for reducing speckle noise in an image projected by a laser beam on the screen, comprising: an array of lenslets arranged in succession along a scan direction, each lenslet having a lenslet dimension, as measured along the scan direction, which is not less than a beam dimension, again as measured along the scan direction, of the laser beam.

16. The display screen of claim 15 , and a polarization rotating coating on alternate lenslets.

17. The display screen of claim 15 , wherein each lenslet has a spherical curvature.

18. An arrangement for projecting an image with reduced speckle noise, comprising:

a) a display screen having front and rear surfaces, and an array of lenslets successively arranged along a scan direction;

b) an image projection assembly for directing a laser beam on the rear surface of the screen, and for sweeping the beam as a pattern of scan lines across the rear surface of the screen, each scan line extending along the scan direction and having a number of pixels, and for causing selected pixels to be illuminated, and rendered visible, to produce the image; and

c) a polarization rotating coating on alternate lenslets for reducing speckle noise.