Spatial light modulation device and spatial light modulation method

Patent metadata

Field	Value
Publication number	US-9223159-B2
Application number	US-201214000428-A
Country	US
Kind code	B2
Filing date	Feb 13, 2012
Priority date	Feb 22, 2011
Publication date	Dec 29, 2015
Grant date	Dec 29, 2015

Abstract

A spatial light modulation device includes a phase-modulation type spatial light modulator, a temperature sensor detecting a temperature of the spatial light modulator, and a control unit providing a drive signal to the spatial light modulator. The control unit has a storage unit. The storage unit stores N correction patterns created so as to correspond to N (N is an integer not less than 2) temperature values of the spatial light modulator in order to correct phase distortion of the spatial light modulator. The control unit selects one correction pattern according to a temperature value of the spatial light modulator, and generates the drive signal based on a phase pattern created by adding the one correction pattern to a desired phase pattern. Thereby, it becomes possible to suppress phase distortion according to a temperature change while suppressing a delay in operation.

First claim

The invention claimed is:

1. A spatial light modulation device comprising:
a spatial light modulator modulating a phase of incident light for each of a plurality of pixels one-dimensionally or two-dimensionally arrayed;
a temperature sensor generating a temperature signal which is a signal corresponding to a temperature of the spatial light modulator; and
a control unit providing a drive signal for controlling a phase modulation amount for each of the plurality of pixels to the spatial light modulator, wherein
the spatial light modulator has a silicon substrate, a liquid crystal layer provided on the silicon substrate, a first electrode disposed between the silicon substrate and the liquid crystal layer, and a second electrode provided at a position so as to sandwich the liquid crystal layer with the first electrode,
the control unit
has storage means storing N correction patterns which are created as correction phase patterns so as to correspond to N (N is an integer not less than 2) temperature values of the spatial light modulator in order to correct phase distortion of the spatial light modulator caused by a warpage of the silicon substrate due to a temperature change in the spatial light modulator, and
selects one correction pattern from among the N correction patterns according to a temperature value indicated by the temperature signal, and generates the drive signal based on a corrected phase pattern which is created by adding the one correction pattern to a desired phase pattern.

2. A spatial light modulation device comprising:
a spatial light modulator modulating a phase of incident light for each of a plurality of pixels one-dimensionally or two-dimensionally arrayed;
a temperature sensor generating a temperature signal which is a signal corresponding to a temperature of the spatial light modulator; and
a control unit providing a drive signal for controlling a phase modulation amount for each of the plurality of pixels to the spatial light modulator, wherein
the spatial light modulator has a silicon substrate, a liquid crystal layer provided on the silicon substrate, a first electrode disposed between the silicon substrate and the liquid crystal layer, and a second electrode provided at a position so as to sandwich the liquid crystal layer with the first electrode,
the control unit
has storage means storing N coefficient value groups calculated from N correction patterns which are created as correction phase patterns so as to correspond to N (N is an integer not less than 2) temperature values of the spatial light modulator in order to correct phase distortion of the spatial light modulator caused by a warpage of the silicon substrate due to a temperature change in the spatial light modulator, and
selects one coefficient value group from among the N coefficient value groups according to a temperature value indicated by the temperature signal, and generates the drive signal based on a corrected phase pattern which is created by adding the correction pattern reconstructed from the one coefficient value group to a desired phase pattern.

3. A spatial light modulation device comprising:
a spatial light modulator modulating a phase of incident light for each of a plurality of pixels one-dimensionally or two-dimensionally arrayed;
a temperature sensor generating a temperature signal which is a signal corresponding to a temperature of the spatial light modulator; and
a control unit providing a drive signal for controlling a phase modulation amount for each of the plurality of pixels to the spatial light modulator, wherein
the spatial light modulator has a silicon substrate, a liquid crystal layer provided on the silicon substrate, a first electrode disposed between the silicon substrate and the liquid crystal layer, and a second electrode provided at a position so as to sandwich the liquid crystal layer with the first electrode,
the control unit
has storage means storing a function of the temperature value and N coefficient value groups calculated from N correction patterns which are created as correction phase patterns so as to correspond to N (N is an integer not less than 2) temperature values of the spatial light modulator in order to correct phase distortion of the spatial light modulator caused by a warpage of the silicon substrate due to a temperature change in the spatial light modulator, and
calculates one coefficient value group from among the N coefficient value groups by applying a temperature value indicated by the temperature signal to the function, and generates the drive signal based on a corrected phase pattern which is created by adding the correction pattern reconstructed from the one coefficient value group to a desired phase pattern.

4. The spatial light modulation device according to claim 2 , wherein
the respective N coefficient value groups contain only coefficient values dependent on a temperature of the spatial light modulator,
the storage means further stores a reference phase pattern created by subtracting a phase pattern reconstructed from the coefficient values dependent on a temperature of the spatial light modulator from the correction pattern at a reference temperature, and
the control unit creates the corrected phase pattern by adding the correction pattern and the reference phase pattern to the desired phase pattern.

5. The spatial light modulation device according to claim 2 , wherein
the respective N coefficient value groups contain only coefficient values whose degrees of dependence on a temperature of the spatial light modulator are higher than a reference,
the storage means further stores a second coefficient value group containing only coefficient values whose degrees of dependence on a temperature of the spatial light modulator are lower than the reference, and
the control unit creates the corrected phase pattern by adding the correction pattern reconstructed from a coefficient value group obtained by combining the one coefficient value group and the second coefficient value group, to the desired phase pattern.

6. The spatial light modulation device according to claim 1 , further comprising a mechanism for controlling a temperature of the spatial light modulator.

7. The spatial light modulation device according to claim 1 , further comprising:
a light source generating the incident light; and
an optical component guiding the incident light from the light source to the spatial light modulator, wherein
each of the N correction patterns is created such that, when a temperature value indicated by the temperature signal is a corresponding temperature value among the N temperature values, the incident light is made incident from the light source into the spatial light modulator in a state in which the drive signal is not provided for the spatial light modulator, and a sign of a phase pattern of emitted light emitted from the spatial light modulator is inverted.

8. The spatial light modulation device according to claim 7 , further comprising:
a measurement unit measuring a phase pattern of the emitted light; and
a correction pattern creation unit creating the N correction patterns by inverting a sign of the phase patterns of the emitted light.

9. A spatial light modulation method which uses a spatial light modulator modulating a phase of incident light for each of a plurality of pixels one-dimensionally or two-dimensionally arrayed and having a silicon substrate, a liquid crystal layer provided on the silicon substrate, a first electrode disposed between the silicon substrate and the liquid crystal layer, and a second electrode provided at a position so as to sandwich the liquid crystal layer with the first electrode, the spatial light modulation method comprising:

Assignees

• Takiguchi Yuu
• Matsumoto Naoya
• OTSU Tomoko
• Hamamatsu Photonics Kk

Inventors

• Takiguchi Yuu
• Matsumoto Naoya
• OTSU Tomoko

Classifications

• G02B26/06 Primary

  for controlling the phase of light (G02B26/08 takes precedence {, measuring optical phase difference G01J9/00}) · CPC title

• G02F2203/21

  Thermal instability, i.e. DC drift, of an optical modulator; Arrangements or methods for the reduction thereof · CPC title

• G02F2203/60

  Temperature independent · CPC title

• G02F1/136

  Liquid crystal cells structurally associated with a semi-conducting layer or substrate, e.g. cells forming part of an integrated circuit (G02F1/135 takes precedence) · CPC title

• G09G3/36

  using liquid crystals · CPC title