Liquid Crystal Optical Modulator for Interferer Suppression
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Solution Overview
Problem
Optical detection systems, such as LIDAR, face challenges when using a single or few photodetectors due to desensitization by bright interferers like the sun, and concentrating received light into a small area can lead to unwanted losses and spatially inefficient optical paths.
Innovation Solution
An optical detection system employing a transmissive liquid crystal structure with adjustable opacity regions, coupled to a control circuit, is used to selectively mask interferers and concentrate scattered or reflected light using a curved reflector, allowing a single photodetector to effectively detect objects while suppressing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single photodetector is used to simplify the optical receiver, then device complexity is reduced, but the detector becomes desensitized by bright interferers such as the sun
Solution Approach 1:
The liquid crystal structure is divided into multiple independently controllable regions (e.g., 8x8 grid of pixels), each of which can be selectively masked or transmitted. This segmentation allows the system to block bright interferers in specific regions while maintaining sensitivity in other regions, thus resolving the contradiction between using a simple single photodetector and avoiding desensitization by bright interferers.
2Measurement precision
If light is concentrated into a small area to improve detection efficiency, then detection sensitivity is improved, but unwanted losses increase and spatial efficiency decreases
Solution Approach 1:
The liquid crystal structure provides dynamic control over light transmission, allowing the system to adaptively adjust which regions transmit light and which mask interferers. This dynamic capability enables the system to concentrate light efficiently while minimizing unwanted losses by only blocking light in regions where interferers are present, rather than uniformly masking the entire field of view.
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 efficient suppression of interference and spatially compact optical detection, allowing for accurate identification of object presence and range using a single photodetector, while maintaining sensitivity and reducing unwanted losses.
Implementation Method 1
an LC structure can have regions of selectable opacity for a specified polarization of incident light
Implementation Method 2
a curved reflector such as a continuously-curved or faceted reflector can be used to concentrate received light and convey such light to a photodetector
Data Source
AI summary
In an optical detection system, received light can be concentrated and presented to a single-pixel photodetector (or an array of relatively few photodetectors). Concentration of received light can be performed by curved concentrator such as a continuously-curved or faceted reflector. A portion or an entirety of the detector might be blinded (e.g., desensitized) by bright interferers such as the sun. An electro-optic shutter such as a liquid crystal (LC) structure can be used to selectively transmit or mask-off portions of the received light. For example, an LC structure can have regions of selectable opacity for a specified polarization of incident light. The LC structure can be controlled to render certain region opaque, such as to suppress interference from unwanted interferers such as the sun, bright lights, or unwanted reflections. An LC structure can also be used to implement a scanned transmit/receive technique.