Liquid Crystal Spatial Light Modulator Wavefront Correction
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Solution Overview
Problem
Conventional high-precision spatial light modulation requires expensive MEMS deformable mirrors, whereas a cost-effective solution using liquid-crystal type spatial light modulators is needed to achieve similar precision.
Innovation Solution
A spatial optical modulating system with a liquid-crystal spatial light modulator and a controller that adjusts voltages applied to electrodes based on phase image data, allowing for variable phase shift amounts per gradation, enabling high-precision modulation and wave front correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a MEMS deformable mirror is used for high-precision wave front correction, then measurement precision is improved, but device cost increases significantly
Solution Approach 1:
The patent replaces the expensive MEMS deformable mirror with an inexpensive liquid crystal spatial light modulator. Although liquid crystal modulators have different operational characteristics, they achieve comparable wave front correction precision through phase modulation, providing a cost-effective alternative that eliminates the need for costly MEMS devices while maintaining ultra-high precision correction capability
Solution Approach 2:
The patent changes the operational parameters of the liquid crystal spatial light modulator by applying individually controllable voltages to each pixel electrode. This enables dynamic phase modulation of the light wave front, transforming the static liquid crystal display into an active wave front correction device that can achieve precision comparable to MEMS deformable mirrors
2Ease of manufacture
If a liquid-crystal spatial light modulator is used instead of MEMS, then device cost is reduced, but phase modulation precision deteriorates
Solution Approach 1:
The patent divides the liquid crystal spatial light modulator into individually controllable pixel electrodes arranged in a two-dimensional array. Each pixel electrode can be independently driven with a specific voltage, enabling precise local phase modulation across the entire aperture. This segmentation allows the system to achieve high precision wave front correction by controlling each pixel's phase contribution, compensating for the inherently lower precision of liquid crystal materials compared to MEMS
Solution Approach 2:
The patent implements a feedback control system where the phase image data from wave front sensing is processed by a controller that calculates the required voltage for each pixel electrode. This closed-loop feedback mechanism continuously adjusts the phase modulation to correct wave front aberrations, enabling the liquid crystal modulator to achieve precision levels comparable to expensive MEMS deformable mirrors
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
This approach enables high-precision spatial light modulation using a relatively inexpensive liquid-crystal type spatial light modulator, effectively correcting wave front aberrations and improving phase resolution, while allowing for flexible use of the gradation range.
Implementation Method 1
The spatial light modulator is provided with a liquid crystal and a plurality of electrodes arranged along a surface of the liquid crystal. The spatial light modulator is configured to perform phase modulation of a light that passes through the liquid crystal by applying individual voltages to the liquid crystal from each of the plurality of electrodes.
Implementation Method 2
The controller is provided with a converter that is configured to convert gradation values, which are the values of each pixel represented by the predetermined gradations, into voltages input to the electrodes corresponding to each pixel. A phase shift amount of the light by the spatial light modulator changes according to the voltages input to the electrodes.
Data Source
AI summary
A system includes a spatial light modulator and a controller. The spatial light modulator is configured to perform phase modulation of a light that passes through a liquid crystal by applying individual voltages to the liquid crystal from each of a plurality of electrodes. The controller is configured to control the voltages applied to the liquid crystal from each of the plurality of electrodes based on phase image data. The phase image data represents values of each pixel corresponding to each of the plurality of electrodes by predetermined gradations. The controller converts gradation values, which are the values of each pixel, into voltages input to the electrodes corresponding to each pixel. The controller is configured to change a fluctuation width from a minimum value to a maximum value of the input voltages corresponding to a fluctuation width from a minimum value to a maximum value of the gradation values.