High contrast tilting ribbon blazed grating

• US 7,057,819 B1
• Filed: 12/17/2002
• Issued: 06/06/2006
• Est. Priority Date: 12/17/2002
• Status: Active Grant

• Current Assignee: Silicon Light Machines Corporation (SCREEN Holdings Co., Ltd.)
• Original Assignee: Silicon Light Machines Corporation (SCREEN Holdings Co., Ltd.)
• Inventors: Maheshwari, Dinesh
• Primary Examiner(s): Robinson, Mark A.
• Assistant Examiner(s): AMARI, ALESSANDRO V
• Application Number:
  US10/322,202
• Time in Patent Office: 1,267 Days
• Field of Search: 359/224, 359/572, 359/573, 359/290, 359/291, 359/292, 359/293, 359/294, 359/295, 359/571
• US Class Current: 359/571
• CPC Class Codes: G02B 26/0808 by means of one or more diffracting elements
• CPC Class Codes: G02B 5/1828 having means for producing variable diffraction controlling the direction of light by means of one or more diffracting elements G02B26/0808; acousto-optical elements G02F1/11, G02F1/33; electro- or magneto-optical diffraction G02F1/292, G02F1/2955

Abstract

The light modulator includes elongated elements and a support structure coupled to the elongated elements. Each element includes one or more lengthwise slits within an active optical area, and a light reflective planar surface with the light reflective planar surfaces lying in a grating plane. The support structure maintains a position of the elongated elements relative to each other and enables tilting of each element about a lengthwise axis. The elongated elements are tilted between a first modulator configuration wherein the elongated elements act to diffract an incident light into one or more diffraction orders, and a second modulator configuration wherein the elongated elements act to diffract the incident light into at least one diffraction order different than the one or more diffraction orders in the first modulator configuration.

Claims

1. A blazed grating device comprising:

a. a plurality of elongated elements, each element including one or more lengthwise slits within an active optical area and a light reflective planar surface, the light reflective planar surfaces lying in a grating plane; and

b. a support structure coupled to the elongated elements to maintain a position of the elongated elements relative to each other and to enable rotational tilting of each element about a lengthwise axis, and between a blazed configuration wherein the elongated elements act to diffract an incident light into a first distribution of diffracted light with first-order diffraction at a first angle θ

1B, and a flat configuration wherein the elongated elements act to diffract the incident light into a second distribution of diffracted light with first-order diffraction at a second angle which is a multiple (at least twice) of the first angle θ

1B,

wherein the one or more slits symmetrically divide the width of the element within the active optical area into a plurality of segments of substantially equal width, and

wherein the elongated elements are rotationally tilted to a blaze angle with respect to the grating plane.

2. The blazed grating device according to claim 1 wherein a width of the slit equals a width of a gap between each element.

3. The blazed grating device according to claim 1 wherein the incident light impinges the active optical area of the elongated elements normal to the grating plane.

4. The blazed grating device according to claim 1 wherein the second angle is about twice the first angle θ

1B.

5. The blazed grating device according to claim 1 wherein the second tangle is about the first θ

1B times the sum of the number of slits plus one.

6. The blazed grating device according to claim 1 wherein a resultant contrast is heightened due to a higher ratio between intensities of the first and second distributions at said first angle θ

1B.

7. The blazed grating device according to claim 1 wherein the slits are cut through the thickness of the elongated element.

8. The blazed grating device according to claim 1 wherein the slits are formed by removing a corresponding portion of the reflective surface of the elongated element.

9. The blazed grating device according to claim 1, wherein said rotational tilting is performed around a lengthwise axis, and wherein the lengthwise axis is a center axis of the elongated element.

10. The blazed grating device according to claim 1, wherein said rotational tilting is performed around a lengthwise axis, and wherein the lengthwise axis is an edge axis of the elongated element.

11. The blazed grating device according to claim 1 further comprising means for applying an electrical bias to each element to enable said rotational tilting of each element.

12. The blazed grating device according to claim 1 wherein a length of each slit is at least as long as a width of the active optical area.

13. A method of diffracting an incident light utilizing a blazed grating comprising:

a. supporting a plurality of elongated elements, each element including one or more lengthwise slits within an active optical area and a light reflective planar surface with the light reflective planar surface, with the light reflective planar surfaces lying in a grating plane;

b. rotationally tilting the plurality of elongated elements about a lengthwise axis, and between blazed configuration and a flat configuration; and

c. diffracting an incident light such that in the blazed configuration the incident light is diffracted into a first distribution of diffracted light with first-order diffraction at a first angle θ

1B and in the flat configuration the incident light is diffracted into a second distribution of diffracted light with first-order diffraction at a second angle which is a multiple (at least twice) of the first angle θ

1B,

wherein each slit is cut through an entire thickness of the elongated element, and

wherein the elongated elements are rotationally tilted to a blaze angle with respect to the grating plane.

14. The method according to claim 13 wherein a resultant contrast is heightened due to a higher ratio between intensities of the first and second distributions at said first angle θ

1B.

15. The method according to claim 13 wherein tilting the plurality of elements is performed by applying an electrical bias to each element.

16. A blazed grating device comprising:

a. means for supporting a plurality of elongated elements, each element including one or more lengthwise slits within an active optical area and a light reflective planar surface, with the light reflective planar surfaces lying in a grating plane;

b. means for rotational tilting the plurality of elongated elements about a lengthwise axis, and between a blazed configuration and a flat configuration; and

c. means for diffracting an incident light such that in the blazed configuration the incident light is diffracted into a first distribution of diffracted light with first-order diffraction at a first angle θ

1B and in the flat configuration the incident light is diffracted into a second distribution of diffracted light with first-order diffraction at a second angle which is a multiple (at least twice) of the first angle θ

1B,

wherein each slit goes through an entire thickness of the elongated element, and

wherein the elongated elements are rotationally tilted to a blaze angle with respect to the grating plane.