Switchable In-Path Optical Diffuser for Satellite Sensor Calibration
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Solution Overview
Problem
Conventional satellite sensor calibration methods are complex and costly, requiring mechanisms to move calibration optics in and out of the sensor's field of view, which increases size, weight, and complexity, and are not suitable for future smaller, lighter, and cheaper sensor requirements.
Innovation Solution
An in-path optical device capable of reversibly switching between a transparent and diffuse state, such as a PDLC device, is integrated into the sensor's optical path, eliminating the need for moving parts and mechanisms for calibration optics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional calibration methods using movable diffusers are used, then calibration capability is maintained, but device complexity and size increase
Solution Approach 1:
The patent merges the calibration diffuser and imaging optic into a single integrated optical element. The diffuser is permanently mounted in the optical path without requiring separate mechanisms to move it in and out, combining two previously separate functions into one unified component that eliminates mechanical complexity while maintaining calibration capability.
Solution Approach 2:
The optical diffuser is designed to serve multiple functions: it acts as a calibration target when needed and simultaneously functions as a permanent optical element in the imaging path. This multi-functionality eliminates the need for dedicated calibration mechanisms, reducing overall device complexity while maintaining both imaging and calibration capabilities.
2Reliability
If movable calibration optics are used, then calibration can be performed, but weight and complexity increase
Solution Approach 1:
The patent extracts the movable mechanism from the calibration system, leaving only the essential calibration function. By making the diffuser permanent and eliminating the need for motors, gears, and control systems required for movement, the weight of moving components is reduced to nearly zero while calibration capability is preserved through alternative means.
Solution Approach 2:
The patent replaces the mechanical system of moving the diffuser in and out of the optical path with an electrical or software-controlled system. The diffuser's optical properties are modulated electronically or through material property changes rather than physical movement, eliminating heavy mechanical components and reducing overall sensor weight.
3Device complexity
If permanent in-path diffuser is used, then complexity is reduced, but risk of optical performance degradation increases
Solution Approach 1:
The patent applies preliminary protective measures by coating the permanent diffuser with anti-degradation layers and selecting materials resistant to space environment effects. The diffuser is pre-conditioned and protected before deployment to prevent performance degradation from UV exposure, atomic oxygen, and thermal cycling, ensuring long-term optical stability without requiring complex active compensation mechanisms.
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 reduces the size, weight, and complexity of satellite sensors while maintaining on-orbit calibration capabilities, ensuring reliable and efficient sensor performance without the risks associated with moving parts.
Implementation Method 1
a plurality of liquid crystals dispersed in a polymer between two conductive layers
Implementation Method 2
an electric field is created between the two conductive layers by the switchable power supply, the electric field aligns the liquid crystals in the polymer
Implementation Method 3
no electric field is created between the two conductive layers, the liquid crystals are misaligned, or randomly orientated in the polymer, and the sensor receives light diffused by the liquid crystals
Data Source
AI summary
Systems and methods of calibrating a sensor using an in-path optic capable of remaining in the sensor's optical path of view for both nominal imaging and for solar calibration collects are described. The optic is reversibly switchable between a transparent state and a diffuse state. An electric field aligns a plurality of liquid crystals dispersed in a polymer between two conductive layers is created to enable the transparent state. Incident light is transmitted through the aligned liquid crystals. The electric field between the two conductive layers is removed, misaligning the plurality of liquid crystals dispersed in the polymer between the two conductive layers. Light dispersed by the misaligned liquid crystals is received, and the sensor is calibrated based on the light dispersed by the misaligned liquid crystals.