Spatial Light Modulator Ribbon Height Correction
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Solution Overview
Problem
Spatial light modulators with diffraction grating structures face challenges in uniformly correcting output light amounts due to variations in the height of moving and fixed ribbons, leading to difficulties in determining appropriate input voltages, especially when the height difference is not uniform, resulting in uneven light distribution and complexity in achieving desired light amounts.
Innovation Solution
A method is introduced to correct output light amounts by setting a target light amount common to all modulator elements, obtaining a target voltage by gradually increasing or decreasing the input voltage, and using provisional voltages to rapidly determine the maximum and minimum light amounts, allowing for precise voltage control and uniform light distribution across the modulator elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the height of moving ribbons is made different from that of fixed ribbons to enable continuous light amount change, then the light modulator can achieve higher adaptability in light control, but it becomes difficult to determine appropriate input voltages and correct output light amounts uniformly across multiple elements
Solution Approach 1:
The patent applies preliminary action by pre-determining correction voltages for each light modulator element before actual image recording. The system measures the output light amount at voltage 0 (or initial state) for each element, compares it to a reference value, and stores correction voltages that will equalize the light amounts. When recording, these pre-calculated correction voltages are applied to all elements simultaneously, eliminating the need for real-time voltage optimization during operation.
Solution Approach 2:
The patent replaces complex mechanical/optical adjustment mechanisms with an electrical correction system. Instead of physically adjusting each light modulator element's ribbon height or optical path to achieve uniform light output, the system uses electrical voltage correction signals applied to electrodes. This substitution simplifies the control mechanism from potential mechanical adjustments to straightforward voltage application based on pre-measured correction values.
2Manufacturing precision
If uniform correction of output light amounts is attempted across all light modulator elements, then light distribution uniformity improves, but the complexity of determining individual correction voltages increases due to manufacturing variations
Solution Approach 1:
The patent implements self-service by enabling each light modulator element to be automatically characterized during an initial measurement phase. The system sequentially applies voltages to each element, measures its output light amount, and automatically determines its specific correction voltage without requiring manual intervention or complex calibration procedures. This self-characterization process simplifies the overall system by allowing automatic adaptation to manufacturing variations.
Solution Approach 2:
The patent applies parameter changes by adjusting the voltage parameter for each light modulator element based on its measured characteristics. Instead of attempting to manufacture all elements with identical parameters (which would increase manufacturing complexity), the system accepts manufacturing variations and compensates by changing the operating voltage parameter for each element individually. This approach trades voltage adjustment complexity for manufacturing simplicity.
3Ease of operation
If the zeroth order light beam is used as reference for correction when moving and fixed ribbons have equal height, then correction process simplifies, but this reference state cannot be established when ribbon heights are inherently different
Solution Approach 1:
The patent applies inversion by reversing the conventional approach: instead of trying to create equal-height ribbons to establish a zeroth-order light reference, the system accepts the unequal-height configuration and uses the first-order diffracted light as the reference. The correction process measures output at voltage 0 (where first-order light is maximum) and uses this as the baseline for determining correction voltages, effectively inverting the traditional reference-based correction methodology.
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 the determination of appropriate target voltages for spatial light modulators with varying ribbon heights, ensuring uniform output light amounts and improving the accuracy and efficiency of image recording by minimizing variations in light distribution.
Implementation Method 1
The moving ribbons are sagged in accordance with a voltage inputted to each light modulator element, to change a height of the moving reflective surfaces from the base surface
Implementation Method 2
each light modulator element changes between a state of emitting a zeroth order light beam and a state of first order diffracted light beams
Implementation Method 3
spatial light modulator with diffraction grating structure
Data Source
AI summary
In each light modulator element of a special light modulator with diffraction grating structure where moving ribbons and fixed ribbons are alternately arranged, the maximum light-amount (I1) when an output light-amount first becomes maximum from when the moving ribbons start to sag and the maximum light amount-voltage becoming an displacement amount (P1) at the maximum light-amount, are obtained and the minimum of a plurality of maximum light-amounts is set as a target ON light-amount (It). Since a voltage (corresponding to a displacement amount (Pt1)) between the maximum light amount-voltage and the minimum light amount-voltage at a displacement amount (P2) is obtained as a target ON-voltage for the target ON light-amount (It), it is thereby possible to prevent moving distance of the moving ribbons among ON/OFF from largely differing among the light modulator elements and achieve an appropriate image recording.