Three dimensional image projector with circular light polarization

• US 8,955,975 B2
• Filed: 11/09/2012
• Issued: 02/17/2015
• Est. Priority Date: 01/25/2012
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: DeCusatis, Casimer M.
• Primary Examiner(s): Epps, Georgia Y
• Assistant Examiner(s): Cruz, Magda
• Application Number:
  US13/672,877
• Publication Number:
  US 20130188151A1
• Time in Patent Office: 830 Days
• Field of Search: 353/8, 353/81, 353/20, 353/98, 348/743, 348/57, 359/583, 359/629, 359/634
• US Class Current: 353/8
• CPC Class Codes: G02B 5/12 Reflex reflectors
• CPC Class Codes: G02B 6/27 with polarisation selective and adjusting means
• CPC Class Codes: G03B 21/2033 LED or laser light sources
• CPC Class Codes: G03B 21/2073 Polarisers in the lamp house peculiar to electronic spatial light modulators H04N9/3197
• CPC Class Codes: G03B 35/26 using polarised or coloured light separating different viewpoint images

Abstract

A method is provided that includes providing a light source having a light emitting diode (LED) that emits a light. A polarization conversion system (PCS) is located adjacent the LED and has both a linear polarizer and a wave plate. A polarizing beam splitter (PBS) is adjacent the light source and an imaging device is adjacent the PBS. The wave plate of the PCS is rotated to a first position, and a first light is emitted by the LED in the first light source. This first light is converted to circular polarization. This first light travels to the PBS where it is reflected onto the imaging device. The wave plate is then rotated to a second position, and a second light is emitted by the light source. This second light is converted to circular polarization and reflects from the PBS onto the imaging device.

Claims

1. A method comprising:

providing a light source having a light emitting diode (LED) that emits a light;

providing a polarization conversion system (PCS) adjacent the LED comprising a linear polarizer and a wave plate, the linear polarizer having an axis of polarization and the wave plate being rotatable between a first and second position about an optic axis of the LED;

providing a polarizing beam splitter (PBS) adjacent the light source;

providing an imaging device adjacent the PBS;

rotating the wave plate of the PCS to a first position;

emitting a first light from the light source when the wave plate of the PCS is in the first position;

converting, at the PCS, the first light to circular polarization;

reflecting the first light with the PBS onto the imaging device;

rotating the wave plate of the PCS to a second position, the second position being 90 degrees apart from the first position;

emitting a second light from the light source when the wave plate is in the second position;

converting the second light to circular polarization; and

,

reflecting the second light with the PBS onto the imaging device subsequent to reflecting the first light onto the imaging device.

2. The method of claim 1, further comprising:

providing a projection lens assembly adjacent the PBS opposite the imaging device;

emitting the first light reflected from the imaging device through the projection lens assembly; and

,

emitting the second light reflected from the imaging device through the projection lens assembly.

3. The method according to claim 1 wherein the circular polarization of the first light is opposite the circular polarization of the second light.

4. The method of claim 1 wherein the wave plate is located in the first position when the wave plate forms a 45 degree angle with the axis of polarization of the linear polarizer.

5. The method of claim 1, wherein the wave plate is located in the second position when the wave plate forms a negative 45 degree angle with the axis of polarization of the linear polarizer.

6. The method of claim 1 wherein the imaging device is a liquid crystal on silicon (LCoS) device.

7. The method of claim 1 wherein the light source additionally comprises a conic section reflector on which the LED is mounted.

8. The method of claim 1 wherein the wave plate of the PCS is in the first position when the first light is emitted and the wave plate of the PCS is in the second position when the second light is emitted.

9. The method of claim 8 further comprising:

rotating the wave plate of the PCS from the second position to the first position; and

emitting a third light from the light source when the wave plate of the PCS is rotated from second position to the first position.

10. The method of claim 9 wherein:

the first light has a left-handed circular polarization;

the second light has a right-handed circular polarization; and

the third light has a left-handed circular polarization.

11. A method comprising:

providing a light source having a light emitting diode (LED) that emits a light;

providing a polarization conversion system (PCS) adjacent the LED comprising a linear polarizer and a wave plate, the linear polarizer having an axis of polarization and the wave plate being rotatable about an optic axis of the LED;

providing a polarizing beam splitter (PBS) adjacent the light source;

providing an imaging device adjacent the PBS;

oscillating the wave plate of the PCS between a first position and a second position, the first position being 90 degrees apart from the second position;

emitting a sequence of light emissions from the LED;

synchronizing the emitting of the light emissions with the oscillating of the wave plate of the PCS, wherein the wave plate of the PCS is oriented in either the first position or second position when light is emitted; and

creating alternating emissions of light having left-handed circular polarization and right-handed circular polarization in response to the sequence of light emissions and the oscillating of the wave plate of the PCS.

12. The method of claim 11 further comprising reflecting the second light with the PBS onto the imaging device subsequent to reflecting the first light onto the imaging device.

13. The method of claim 12 wherein the wave plate is located in the first position when the wave plate forms a 45 degree angle with the axis of polarization of the linear polarizer.

14. The method of claim 12, wherein the wave plate is located in the second position when the wave plate forms a negative 45 degree angle with the axis of polarization of the linear polarizer.

15. The method of claim 12 wherein the imaging device is a liquid crystal on silicon (LCoS) device.

16. The method of claim 12 wherein the light source additionally comprises a conic section reflector on which the LED is mounted.