Polarization light modulator

• US 7,286,277 B2
• Filed: 01/20/2006
• Issued: 10/23/2007
• Est. Priority Date: 11/26/2004
• Status: Active Grant

• Current Assignee: Mantis Vision, Ltd.
• Original Assignee: Alces Technology, Inc. (Mantis Vision, Ltd.)
• Inventors: Bloom, David M., Peterman, Mark C.
• Primary Examiner(s): Schwartz; Jordan
• Assistant Examiner(s): JONES, JAMES
• Application Number:
  US11/336,277
• Publication Number:
  US 20060114544A1
• Time in Patent Office: 641 Days
• Field of Search: 359/279
• US Class Current: 359/279
• CPC Class Codes: G02B 26/06 for controlling the phase of light G02B26/08 takes precedence , measuring optical phase difference G01J9/00
• CPC Class Codes: G02B 26/0808 by means of one or more diffracting elements
• CPC Class Codes: G02B 26/0825 the reflecting element being a flexible sheet or membrane, e.g. for varying the focus flexible mirrors for cosmetic use A45D42/24
• CPC Class Codes: G02B 27/283 used for beam splitting or combining

Abstract

Polarization light modulators are based on an interferometric design in which a polarizing beam splitter serves as a polarizer and analyzer. A polarization displacement device shifts orthogonally polarized light beams parallel to the long axis of their elongated cross sections. Phase shifts are imparted to the orthogonally polarized beams by linear array MEMS optical phase shift devices. The output of the light modulator is a line image which may be scanned to form a two-dimensional image. Features to improve brightness, contrast and overall compactness of design are disclosed.

Claims

1. A polarization light modulator comprising:

a polarizing beam splitter;

a polarization displacement device; and

,

a MEMS optical phase shift device;

wherein,

light propagates through the polarizing beam splitter and the polarization displacement device before arriving at the MEMS optical phase shift device in a beam of elongated cross section oriented perpendicular to ribbons in the MEMS optical phase shift device.

2. A modulator as in claim 1 wherein the polarization displacement device offsets orthogonal polarizations of light in a direction parallel to the long axis of the elongated cross section.

3. A modulator as in claim 2 wherein the polarizing beam splitter also functions as a scanning mirror.

4. A modulator as in claim 2 wherein a line image output from the modulator is focused near infinity for close viewing by an observer.

5. A modulator as in claim 2 further comprising an aperture that blocks stray light from arriving at the MEMS optical phase shift device.

6. A modulator as in claim 2 further comprising a double-slit aperture that improves contrast in a line image.

7. A modulator as in claim 2 wherein the MEMS optical phase shift device comprises ribbons of alternating stiffness.

8. A modulator as in claim 2 wherein the MEMS optical phase shift device comprises ribbons which are supported at their ends and in which alternating ribbons are further supported by intermediate supports.