Spatial light modulator featured with an anti-reflective structure

• US 7,542,197 B2
• Filed: 07/11/2007
• Issued: 06/02/2009
• Est. Priority Date: 11/01/2003
• Status: Expired due to Fees

• Current Assignee: Ignite USA (Ignite)
• Original Assignee: Olympus Corporation, Silicon Quest Kabushiki-Kaisha
• Inventors: Maeda, Yoshihiro, Ichikawa, Hirotoshi, Watanabe, Kazuhiro, Ishii, Fusao, Horikawa, Yoshiaki
• Primary Examiner(s): Sugarman; Scott J
• Assistant Examiner(s): Thomas; Brandi N
• Application Number:
  US11/827,552
• Publication Number:
  US 20080013157A1
• Time in Patent Office: 692 Days
• Field of Search: 359/290, 359/291, 359/292, 359/295, 359/298
• US Class Current: 359/290
• CPC Class Codes: G02B 1/118 having sub-optical wavelength surface structures designed to provide an enhanced transmittance, e.g. moth-eye structures
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G02F 1/136277 formed on a semiconductor substrate, e.g. of silicon
• CPC Class Codes: G02F 2201/38 Anti-reflection arrangements
• CPC Class Codes: G02F 2203/12 spatial light modulator
• CPC Class Codes: H04N 9/3141 Constructional details thereof details not peculiar to the presence of an electronic spatial light modulator G03B21/14

Abstract

A spatial light modulator supported on a device substrate includes a plurality of light modulation elements to modulate a light emitted from a light source. The spatial light modulator and the device substrate further comprises a cyclic structure on a surface of the spatial light modulator and/or the device substrate for preventing a reflection of the incident light from the cyclic structure. In an exemplary embodiment the cyclic structure includes cyclic structural elements having a distance between two cyclic elements shorter than the wavelength of an incident light for preventing a reflection of the incident light from the cyclic structure.

Claims

1. An image projection system comprising:

a spatial light modulator supported on a device substrate for controlling a light modulation element further including a hinge disposed on said device substrate to support a mirror at a distance above said device substrate to reflect and modulate an incident light emitted from a light source;

an antireflection structure comprising cyclic protrusions extended from a surface of said device substrate underneath said light modulating element wherein a distance between two of said cyclic protrusions is shorter than a wavelength of an incident light for preventing a reflection of said incident light from said antireflection structure;

said cyclic protrusions having a cross sectional shape of substantially side-by-side vertical triangles; and

said side-by-side triangles is characterized by;

λ

>

P>

λ

/2, and

H/W>

3, where

the P is a pitch between top vertex points of the side-by-side triangles, the λ

is the wavelength of the incident light, the H is the height of the side-by-side triangles, and the W is a base width of the side-by-side triangles.

2. The image projection system according to claim 1 wherein:

said antireflection structure is disposed on a backside of said mirror for preventing a reflection of light from said backside of said mirror.

3. The image projection system according to claim 1 wherein:

said antireflection structure is disposed on a top surface of said device substrate underneath a gap between two adjacent mirrors.

4. The image projection system according to claim 1, comprising:

the antireflection structure is disposed on a top surface of the device substrate adjacent to said hinge underneath said mirror.

5. The image projection system according to claim 1, wherein:

the spatial light modulator further comprising a plurality of light modulation elements each having a mirror for reflecting and modulating the incident light wherein said antireflection structure is disposed on a backside surface of the mirror of each of said light modulation elements.

6. An image display apparatus comprising:

a spatial light modulator modulating an incident light emitted from a light source;

a device substrate for supporting said spatial light modulator thereon wherein said device substrate further includes an antireflection structure comprising cyclic protrusions extended from a top surface of said device substrate having a cross sectional shape of substantially side-by-side triangles wherein a distance; and

said side-by-side triangles is characterized by;

λ

>

P>

λ

/2, and

H/W>

3, where

the P is a pitch between top vertex points of the side-by-side triangles, the λ

is the wavelength of the incident light, the H is the height of the side-by-side triangles, and the W is a base width of the side-by-side triangles.

7. The image projection system according to claim 6 wherein:

said spatial light modulator is contained in a package and said antireflection structure is disposed on internal walls of said package for preventing a reflection from said internal walls of said package.

8. The image projection system according to claim 6, wherein

said spatial light modulator is contained in a package and said antireflection structure is disposed on outer walls of said package for preventing a reflection from said outer walls of said package.

9. The image projection system according to claim 6, comprising:

the cyclic structure is disposed on a top surface and a bottom surface opposite said top surface of the device substrate.

10. The image display apparatus according to claim 6, further comprising

a light source for projecting a polarized incident light, and

the antireflection structure is oriented in one direction parallel with a polarization direction of the polarized incident light.

11. The image display apparatus according to claim 6, further comprising

a light source for projecting a polarized incident light, and

the antireflection structure is oriented in one direction perpendicular to a polarization direction of the polarized incident light.

12. The image projection system according to claim 6 wherein:

said spatial light modulator is contained in a package with a cover member and said antireflection structure is disposed on a surface of said cover member.

13. The image projection system according to claim 6 wherein:

said spatial light modulator is contained in a package with a cover member and said antireflection structure is disposed on an inner surface and an outer surface of said cover member.

14. A method of manufacturing a spatial light modulator for modulating an incident light projected thereon comprising

applying an imprinting method, etching method or sol-gel method for forming an antireflection structure comprising a plurality of cyclic protrusions to having a cross sectional shape of substantially side-by-side triangles extend from a top surface of a device substrate preventing a reflection of said incident light from said antireflection structure;

and

said side-by-side triangles is characterized by;

λ

>

P>

λ

/2, and

H/W>

3, where

the P is a pitch between top vertex points of the side-by-side triangles, the λ

is the wavelength of the incident light, the H is the height of the side-by-side triangles, and the W is a base width of the side-by-side triangles.