Spatial light modulator, and spatial light modulating method

Patent metadata

Field	Value
Publication number	US-9250458-B2
Application number	US-201213985083-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, and in the storage means, one or a plurality of first coefficients included in a first 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 plurality of second coefficients included in a second function which is a nonlinear function expressing a correlation between an applied voltage and a phase modulation amount at the reference temperature are stored in advance, and
the voltage generation unit carries out a calculation for correcting a phase modulation amount indicated value which is a target value of a phase modulation amount by use of a temperature indicated by the temperature signal provided from the temperature sensor, and the one or plurality of first coefficients, thereafter converts the phase modulation amount indicated value into an applied voltage corresponding value by use of the plurality of second coefficients, and provides the voltage corresponding to the applied voltage corresponding value to the plurality of pixel electrodes.

2. The spatial light modulation device according to claim 1 , wherein the voltage generation unit transforms a desired phase modulation amount into a control input value which is a value for controlling the voltage and whose relationship with the phase modulation amount is able to be handled as linear, and generates the phase modulation amount indicated value based on the control input value.

3. The spatial light modulation device according to claim 1 , wherein the voltage generation unit stores the corrected phase modulation amount indicated value and the applied voltage corresponding value calculated based on the phase modulation amount indicated value, and in the case where there is an applied voltage corresponding value corresponding to the corrected phase modulation amount indicated value, without performing a calculation, provides the voltage corresponding to the applied voltage corresponding value to the plurality of pixel electrodes.

4. 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 first coefficients from storage means storing in advance the one or plurality of first coefficients included in a first 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 plurality of second coefficients included in a second function which is a nonlinear function expressing a correlation between an applied voltage and a phase modulation amount at the reference temperature, and carrying out a calculation for correcting a phase modulation amount indicated value which is a target value of a phase modulation amount by use of a temperature indicated by the temperature signal, and the one or plurality of first coefficients;
a voltage conversion step of reading out the plurality of second coefficients from the storage means, and converting the phase modulation amount indicated value into an applied voltage corresponding value by use of the plurality of second coefficients; and
a voltage application step of providing the voltage corresponding to the applied voltage corresponding value to the plurality of pixel electrodes.

5. The spatial light modulation method according to claim 4 , wherein, in the correction calculation step, a desired phase modulation amount is transformed into a control input value which is a value for controlling the voltage and whose relationship with the phase modulation amount is able to be handled as linear, and the phase modulation amount indicated value is generated based on the control input value.

6. The spatial light modulation method according to claim 4 , wherein, in the voltage conversion step, the corrected phase modulation amount indicated value and the applied voltage corresponding value calculated based on the phase modulation amount indicated value are stored, and in the case where there is an applied voltage corresponding value corresponding to the corrected phase modulation amount indicated value, in the voltage application step, without performing a calculation, the voltage corresponding to the applied voltage corresponding value is provided to the plurality of pixel electrodes.

7. 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, and in the storage means, one or a plurality of first coefficients included in a first 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 plurality of second coefficients included in a second function which is a nonlinear function expressing a correlation between an applied voltage and a phase modulation amount are stored in advance, and
the voltage generation unit carries out a calculation for correcting a phase modulation amount indicated value which is a target value of a phase modulation amount by use of a temperature indicated by the temperature signal provided from the temperature sensor, and the one or plurality of first coefficients, thereafter converts the phase modulation amount indicated value into an applied voltage corresponding value by use of the plurality of second coefficients, and provides the voltage corresponding to the applied voltage corresponding value to the plurality of pixel electrodes,
the first function is a linear function, and the number of the first coefficients is one, and
the voltage generation unit corrects the phase modulation amount indicated value based on the following formula:

Assignees

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

Inventors

• OTSU Tomoko
• Matsumoto Naoya
• Takiguchi Yuu

Classifications

• G02F1/13306 Primary

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

• G09G2320/0285

  using tables for spatial correction of display data · CPC title

• G02F2203/12

  spatial light modulator · CPC title

• G09G2360/145

  the light originating from the display screen · CPC title

• G09G3/3611 Primary

  Control of matrices with row and column drivers · CPC title