Liquid crystal modulator including a diffuser with plural phase shifting regions

• US 5,225,920 A
• Filed: 04/04/1991
• Issued: 07/06/1993
• Est. Priority Date: 04/06/1990
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Kato, Makoto, Kasazumi, Kenichi, Kobayashi, Ikunori
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): TRICE, RONALD
• Application Number:
  US07/680,484
• Time in Patent Office: 824 Days
• Field of Search: 359/69, 359/48, 359/62, 359/74, 359/82, 359/95
• US Class Current: 349/1
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G03H 1/04 Processes or apparatus for producing holograms G03H1/26 takes precedence
• CPC Class Codes: G03H 1/16 using Fourier transform G03H1/10, G03H1/12, G03H1/14 take precedence; analogue computers G06G, e.g. G06G7/19
• CPC Class Codes: G03H 1/268 Holographic stereogram
• CPC Class Codes: G03H 2210/12 Phase modulating object, e.g. living cell
• CPC Class Codes: G03H 2210/22 2D SLM object wherein the object beam is formed of the light modulated by the SLM
• CPC Class Codes: G03H 2222/31 Polarised light
• CPC Class Codes: G03H 2223/13 Phase mask
• CPC Class Codes: G03H 2225/55 Having optical element registered to each pixel

Abstract

Light emitted from a coherent light source undergoes fine adjustment of its polarizing direction by a polarizing device and is directed to a liquid crystal device through a collimating optical system. The polarizing device is capable of fine-adjusting the polarizing direction in accordance with the wavelength of the incident light, thereby providing a high contrast ratio. When an image is recorded by holography using such a liquid crystal spacial light modulator, it is possible to obtain an image of high quality.

Claims

1. A liquid crystal spacial light modulator comprising:

a coherent light source;

a polarizing device capable of fine-adjusting the polarizing direction of the light emitted from the coherent light source;

a collimating optical system into which the light with its polarizing direction adjusted by the polarizing device is introduced;

a liquid crystal device into which the light passing through the collimating optical system is introduced for transmission therethrough and which modulates the intensity of the transmitting light in accordance with image data; and

a diffuser which has a plurality of phase shift regions arranged at a prescribed pitch and is disposed on an incident light side of the liquid crystal device, at least two of the plurality of phase shift regions of the diffuser being arranged in a manner to correspond to one pixel of the liquid crystal device.

2. A liquid crystal spacial light modulator according to claim 1, wherein a polarizing plate is provided on an outgoing light side of the liquid crystal device.

3. A liquid crystal spacial light modulator according to claim 1, wherein the phase retardation of the phase shift regions of the diffuser is 0, π

/2, π

or 3 π

/2, and the phase difference between adjacent phase shift regions of the diffuser is π

/2.

4. A liquid crystal spacial light modulator according to claim 1, wherein the phase retardation of the phase shift regions of the diffuser is 0, π

/3 or 2 π

/3, and the phase difference between adjacent phase shift regions of the diffuser is π

/3.

5. A liquid crystal spacial light modulator according to claim 1, wherein a glass plate with anti-reflection coating on an outgoing light surface thereof is provided on an outgoing light side of the liquid crystal device.

6. A liquid crystal spacial light modulator according to claim 1, wherein a glass plate is provided on an outgoing light surface of the liquid crystal device, the glass plate consisting of a transparent plate having an outgoing light surface and an incident light surface, the outgoing light surface of the transparent plate being slanted with respect to the incident light surface thereof, and the glass plate being disposed so that the outgoing light surface thereof is slanted with respect to the outgoing light surface of the liquid crystal device.

7. A liquid crystal spacial light modulator according to claim 1, wherein a glass plate is provided on an outgoing light surface of the liquid crystal device, the glass plate consisting of a transparent plate having an outgoing light surface and an incident light surface, the incident light and outgoing light surfaces of the transparent plate being parallel to each other, and the glass plate being disposed so that the outgoing light surface thereof is slanted with respect to the outgoing light surface of the liquid crystal device.

8. A liquid crystal spacial light modulator comprising:

a coherent light source;

a polarizing device capable of fine-adjusting the polarizing direction of the light emitted from the coherent light source;

a collimating optical system into which the light with its polarizing direction adjusted by the polarizing device is introduced;

a liquid crystal device into which the light passing through the collimating optical system is introduced for transmission therethrough and which modulates the intensity of the transmitting light in accordance with image data; and

a diffuser which has a plurality of phase shift regions arranged at a prescribed pitch and is disposed on an incident light side of the liquid crystal device, at least two of the plurality of phase shift regions of the diffuser being arranged in a manner to correspond to one pixel of the liquid crystal device;

wherein a glass plate with anti-reflection coating on an outgoing light surface of the glass plate is provided on an outgoing light side of the liquid crystal device, the glass plate consisting of a transparent plate having an outgoing light surface and an incident light surface, the outgoing light surface of the transparent plate being slanted with respect to the incident light surface of the transparent plate, and the glass plate being disposed so that the outgoing light surface of the glass plate is slanted with respect to the outgoing light surface of the liquid crystal device.

9. A liquid crystal spacial light modulator comprising:

a coherent light source;

a polarizing device capable of fine-adjusting the polarizing direction of the light emitted from the coherent light source;

a collimating optical system into which the light with its polarizing direction adjusted by the polarizing device is introduced;

a liquid crystal device into which the light passing through the collimating optical system is introduced for transmission therethrough and which modulates the intensity of the transmitting light in accordance with image data; and

a diffuser which has a plurality of phase shift regions arranged at a prescribed pitch and is disposed on an incident light side of the liquid crystal device, at least two of the plurality of phase shift regions of the diffuser being arranged in a manner to correspond to one pixel of the liquid crystal device;

wherein a glass plate with anti-reflecting coating on an outgoing light surface of the glass plate is provided on an outgoing light side of the liquid crystal device, the glass plate consisting of a transparent plate having an outgoing light surface and an incident light surface, the incident light and outgoing light surfaces of the transparent plate being parallel to each other, and the glass plate being disposed so that the outgoing light surface of the glass plate is slanted with respect to the outgoing light surface of the liquid crystal device.