Spatial light modulator, and spatial light modulating method

Patent metadata

Field	Value
Publication number	US-9250459-B2
Application number	US-201213985214-A
Country	US
Kind code	B2
Filing date	Feb 10, 2012
Priority date	Feb 15, 2011
Publication date	Feb 2, 2016
Grant date	Feb 2, 2016

Abstract

A spatial light modulation device includes a liquid crystal layer modulating a phase of incident light according to a level of an applied electric field, a temperature sensor generating a temperature signal corresponding to a temperature of the liquid crystal layer, a plurality of pixel electrodes provided for each of a plurality of pixels and applying a voltage to the liquid crystal layer, and a driving device providing a voltage to the plurality of pixel electrodes. The driving device has a nonvolatile storage element storing in advance a coefficient α included in a function expressing a correlation between a temperature change amount in the liquid crystal layer and a variation in phase modulation amount in the liquid crystal layer, and performs a calculation for correcting a level of voltage by use of a temperature indicated by the temperature signal and the coefficient α.

First claim

The invention claimed is:

1. A spatial light modulation device which modulates a phase of incident light for each of a plurality of pixels one-dimensionally or two-dimensionally arrayed, the device comprising:
a liquid crystal layer modulating a phase of the incident light according to a level of an applied electric field;
a temperature sensor generating a temperature signal which is a signal corresponding to a temperature of the liquid crystal layer;
a plurality of pixel electrodes which are provided for each of the plurality of pixels and apply a voltage for generating the applied electric field to the liquid crystal layer; and
a voltage generation unit providing the voltage to the plurality of pixel electrodes, wherein
the voltage generation unit has storage means storing in advance one or a plurality of coefficients included in a function expressing a correlation between a temperature change amount with respect to a reference temperature of the liquid crystal layer and a variation in phase modulation amount in the liquid crystal layer, and a look up table for correcting nonlinearity between a level of the voltage and the phase modulation amount at the reference temperature, and
carries out a calculation for correcting the level of the voltage to be applied to each pixel electrode by correcting a control input value S for controlling the level of the voltage by use of a temperature indicated by the temperature signal provided from the temperature sensor and the one or plurality of coefficients, and determining the level of the voltage based on the corrected control input value S by use of the look up table.

2. A spatial light modulation method which uses a liquid crystal layer modulating a phase of incident light according to a level of an applied electric field, and a plurality of pixel electrodes which are provided for each of a plurality of pixels one-dimensionally or two-dimensionally arrayed, and apply a voltage for generating the applied electric field to the liquid crystal layer, the method comprising:
a temperature acquisition step of acquiring a temperature signal which is a signal corresponding to a temperature of the liquid crystal layer from a temperature sensor;
a correction calculation step of reading out one or a plurality of coefficients and a look up table from storage means storing in advance the one or plurality of coefficients included in a function expressing a correlation between a temperature change amount with respect to a reference temperature of the liquid crystal layer and a variation in phase modulation amount in the liquid crystal layer, and the look up table for correcting nonlinearity between a level of the voltage and the phase modulation amount at the reference temperature, and
carrying out a calculation for correcting the level of the voltage to be applied to each pixel electrode by correcting a control input value S for controlling the level of the voltage by use of a temperature indicated by the temperature signal and the one or plurality of coefficients, and determining the level of the voltage based on the corrected control input value S by use of the look up table; and
a voltage application step of providing the corrected voltage to the plurality of pixel electrodes.

3. A spatial light modulation device which modulates a phase of incident light for each of a plurality of pixels one-dimensionally or two-dimensionally arrayed, the device comprising:
a liquid crystal layer modulating a phase of the incident light according to a level of an applied electric field;
a temperature sensor generating a temperature signal which is a signal corresponding to a temperature of the liquid crystal layer;
a plurality of pixel electrodes which are provided for each of the plurality of pixels and apply a voltage for generating the applied electric field to the liquid crystal layer; and
a voltage generation unit providing the voltage to the plurality of pixel electrodes, wherein
the voltage generation unit has storage means storing in advance one or a plurality of coefficients included in a function expressing a correlation between a temperature change amount with respect to a reference temperature of the liquid crystal layer and a variation in phase modulation amount in the liquid crystal layer, and carries out a calculation for correcting a level of the voltage by use of a temperature indicated by the temperature signal provided from the temperature sensor, and the one or plurality of coefficients,
the function is a linear function, and the number of the coefficients is one, and
the voltage generation unit corrects a control input value S for controlling a level of the voltage based on the following formula:

S
=

S
⁢

⁢
0

100
-

(

T
-

T
⁢

⁢
0

)

×
α

×
100

(where, T is a temperature indicated by the temperature signal provided from the temperature sensor, T 0 is a reference temperature, S 0 is a control input value for obtaining a desired phase modulation amount at the reference temperature T 0 , and α is the coefficient).

4. A spatial light modulation device which modulates a phase of incident light for each of a plurality of pixels one-dimensionally or two-dimensionally arrayed, the device comprising:
a liquid crystal layer modulating a phase of the incident light according to a level of an applied electric field;
a temperature sensor generating a temperature signal which is a signal corresponding to a temperature of the liquid crystal layer;
a plurality of pixel electrodes which are provided for each of the plurality of pixels and apply a voltage for generating the applied electric field to the liquid crystal layer; and
a voltage generation unit providing the voltage to the plurality of pixel electrodes, wherein
the voltage generation unit has storage means storing in advance one or a plurality of coefficients included in a function expressing a correlation between a temperature change amount with respect to a reference temperature of the liquid crystal layer and a variation in phase modulation amount in the liquid crystal layer, and carries out a calculation for correcting a level of the voltage by use of a temperature indicated by the temperature signal provided from the temperature sensor, and the one or plurality of coefficients,
the function is an n-th order function (n is an integer not less than 2), and the number of the coefficients is n, and
the voltage generation unit corrects a control input value S for controlling a level of the voltage based on the following formula:

S
=

S
⁢

Assignees

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

Inventors

• OTSU Tomoko
• Matsumoto Naoya
• Takiguchi Yuu

Classifications

• G09G2360/145

  the light originating from the display screen · CPC title

• G09G3/3611 Primary

  Control of matrices with row and column drivers · CPC title

• G02F1/13306 Primary

  Circuit arrangements or driving methods for the control of single liquid crystal cells (G02F1/132, G02F1/133382 take precedence) · CPC title

• G09G2320/041

  Temperature compensation · CPC title

• G09G2320/0285

  using tables for spatial correction of display data · CPC title