Spatial Light Modulator High Spatial Frequency Border
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Solution Overview
Problem
Existing spatial light modulators (SLMs) suffer from unwanted zero-order reflections due to light interacting with the substrate outside the active pixel array, leading to undesirable zero-spatial-frequency spots, which current methods like underfilling or using dummy pixels fail to adequately address without compromising device performance.
Innovation Solution
A spatial light modulator design featuring individually-addressed phase-modulating pixels with a higher spatial frequency border array, where the border pixels are configured to impart additional phase modulations, steering peripheral light outside the target range of angles, thereby minimizing zero-order reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If dummy pixels or mechanical blocking structures are used around the pixel array, then zero-order reflections are reduced, but device complexity increases and positioning precision becomes difficult to achieve
Solution Approach 1:
The pixel array is segmented into two distinct regions: active pixels for information modulation and border pixels for suppressing zero-order reflections. This segmentation allows each region to be optimized for its specific function, with border pixels being non individually-addressable and electrically connected together to collectively manage peripheral light
Solution Approach 2:
The function of suppressing zero-order reflections is extracted from the active pixel array and assigned to a separate border pixel region. This extraction allows the active pixels to focus solely on information modulation while the border pixels handle the harmful reflection suppression
2Object-generated harmful factors
If the beam size is reduced to underfill the active area, then zero-order reflections are minimized, but device performance decreases due to wasted active pixels
Solution Approach 1:
Different regions of the pixel array are assigned different functions: the central active pixel array maintains full illumination for information modulation, while the peripheral border pixel region is specifically designed to handle peripheral light. This local differentiation eliminates the need to reduce overall beam size while still suppressing zero-order reflections
3Adaptability or versatility
If peripheral light is allowed to reflect off the substrate, then beam steering coverage is maximized, but zero-spatial-frequency spots are created that are undesirable in many applications
Solution Approach 1:
The border pixels convert the harmful peripheral light that would create zero-order reflections into a beneficial effect by diffracting it into higher spatial frequencies. The border pixels act as a diffraction grating that redirects peripheral light away from the zero-order direction, transforming a harmful factor into a solution
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 effectively reduces unwanted zero-order reflections by redirecting peripheral light outside the target range, enhancing the SLM's performance without wasting active pixel illumination, thus improving beam steering accuracy and efficiency.
Implementation Method 1
individually-addressed phase-modulating pixels configured to reflect and modify phasing of a beam of coherent light incident on the spatial light modulator
Implementation Method 2
The pixels can be configured to reflect and modify phasing of a beam of coherent light
Implementation Method 3
The second array can have a second spatial frequency of N′, where N′>N, and can be configured to impart M different phase delays to a peripheral portion of the beam outside the target range of angles
Data Source
AI summary
A spatial light modulator having an active and a peripheral region, wherein coherent light impinges on both regions, but due to a higher spatial frequency of pixels within the peripheral region, and due to biasing the peripheral region pixels to maximize dispersion of reflected light therefrom, a majority of light reflected from the peripheral region is directed outside of a three-dimensional target window. A spatial frequency of the pixels in the active region is selected such that maximum dispersion of reflected light from the active region is incident within the three-dimensional target window. In this way, incident light that does not reflect from the active region need not be absorbed, or blocked, but instead can be reflected, but still fails to interfere with the target window.