LCOS Phase Modulation Correction via Voltage-LUT Mapping
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Solution Overview
Problem
Conventional LCOS spatial light modulators face challenges in accurately correcting phase modulation characteristics due to nonlinear voltage-dependent phase modulation and voltage-independent distortion, especially when input light conditions such as angle and wavelength change, leading to inefficiencies in phase modulation control.
Innovation Solution
A phase modulating apparatus comprising a reflective electric address spatial light modulator with input light condition inputting, correction condition determining, input value setting, and driving means to convert input values into appropriate voltage values, using look-up tables and correction coefficients to ensure accurate phase modulation across varying input conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If voltage is applied to pixel electrode to rotate liquid crystal molecules for phase modulation, then phase modulation function is achieved, but phase modulation amount changes nonlinearly relative to applied voltage
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing correction values in a look-up table that compensates for the nonlinear voltage-dependent phase modulation characteristics. Before actual phase modulation operations, the system characterizes the nonlinear behavior and creates correction data that is applied in advance to linearize the relationship between applied voltage and phase modulation amount.
Solution Approach 2:
The patent changes the parameter relationship by introducing correction coefficients that transform the nonlinear voltage-phase modulation relationship into a linear one. By applying these correction coefficients to the input signals, the system modifies the effective parameters to achieve predictable linear phase modulation despite the inherent nonlinear liquid crystal response.
2Ease of manufacture
If silicon substrate is processed through semiconductor process, then LCOS spatial light modulator is manufactured, but mechanical strength becomes weak and substrate distorts
Solution Approach 1:
The patent replaces mechanical correction approaches with computational correction methods. Instead of mechanically reinforcing the silicon substrate or correcting its distortion through physical means, the system uses software-based phase correction algorithms and look-up tables to compensate for the distortion effects, substituting mechanical solutions with computational ones.
3Manufacturing precision
If correction methods are applied for voltage-dependent phase modulation characteristic, then phase modulation accuracy improves, but device complexity increases
Solution Approach 1:
The patent uses copying by creating a digital model (look-up table) that replicates the nonlinear phase modulation characteristics. Instead of physically modifying the liquid crystal device or adding complex hardware correction mechanisms, the system creates a digital copy of the error characteristics and uses it to generate corrected drive signals, simplifying the correction approach.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The apparatus enables precise correction of phase modulation characteristics, ensuring consistent and accurate phase modulation amounts even with changes in input light conditions, enhancing the control and stability of phase modulation in LCOS spatial light modulators.
Implementation Method 1
When a voltage is applied to a pixel electrode, liquid crystal molecules of the LCOS-spatial light modulator are rotated on a surface vertical to a substrate to change a phase modulation amount of an incident light
Implementation Method 2
change a phase modulation amount of an incident light
Implementation Method 3
Δn(V) denotes a birefringence relative to a polarization component having an electric field vibrating in a direction parallel to an orientation of liquid crystal
Data Source
AI summary
The present invention relates to a phase modulating apparatus capable of highly accurately and easily correcting the phase modulation characteristic of a reflective electric address spatial light modulator even when a condition of input light is changed. In the LCOS phase modulating apparatus, an input unit inputs the condition of the input light, and a processing unit sets an input value for each pixel. A correction value deriving unit determines a correction condition according to the condition of the input light. A control input value converting unit converts the input value set for each pixel into a corrected input value based on the correction condition. An LUT processing unit converts the corrected input value into a voltage value, and drives each pixel by using a drive voltage equivalent to the converted voltage value.