Optically powered cryogenic focal plane array (FPA) with an optical data link
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Solution Overview
Problem
Cryogenic focal plane arrays (FPAs) face challenges with heat leakage and electromagnetic interference (EMI) due to electrical penetrations, which become exacerbated as data transfer rates increase, making it impractical to add more electronic data transmission lines without compromising the cooling system's capacity, size, and weight.
Innovation Solution
Implementing an optical data link that powers the cryogenic FPA optically, eliminating electrical penetrations and using a single optical penetration for both power delivery and data transfer, thereby reducing heat leaks and EMI, and incorporating an optical-to-electrical converter to manage power and data signals within the chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If electrical lines are used to carry power and data into/out of the cryogenic volume, then power and data transmission are enabled, but thermal losses and electromagnetic interference increase
Solution Approach 1:
The patent replaces electrical transmission lines with optical transmission media (optical fibers or free-space optical links) to carry both power and data signals. This substitution eliminates the thermal conduction path that electrical wires create through the chamber walls, thereby reducing thermal losses while maintaining power and data transmission capabilities.
Solution Approach 2:
The patent introduces an optical-to-electrical converter (photodetector array) as an intermediary component inside the cryogenic chamber. This converter receives optical power signals through the chamber wall, converts them to electrical signals, and provides power to the focal plane array and readout circuitry without requiring direct electrical connections through the chamber walls.
2Productivity
If multiple electrical lines are added to increase data transfer rates, then data transmission capacity is improved, but the number of thermal conduction paths increases
Solution Approach 1:
The patent replaces multiple electrical data transmission lines with a single optical transmission channel. Optical fibers or free-space optical links can carry high-bandwidth data signals without conducting heat, enabling increased data transfer rates without proportionally increasing thermal conduction paths through the chamber walls.
3Adaptability or versatility
If electrical penetrations are used to provide power and data signals, then system functionality is enabled, but electromagnetic interference is introduced
Solution Approach 1:
The patent substitutes electrical signal transmission with optical signal transmission for data communication. Optical signals do not generate electromagnetic interference, thereby eliminating this harmful effect while maintaining full data transmission functionality between the cryogenic chamber and external systems.
4Loss of energy
If a single optical penetration is used for power and data, then thermal losses are reduced, but optical-to-electrical conversion is required
Solution Approach 1:
The patent employs photodetector arrays that inherently perform both optical detection and electrical signal generation functions. The optical-to-electrical conversion is achieved through the fundamental photoelectric effect in the detector material, which converts incident photons directly into electrical signals without requiring separate conversion hardware, thereby minimizing added complexity.
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 solution significantly reduces thermal losses and EMI, allowing for higher data transfer rates while maintaining system compatibility, as it eliminates the need for multiple electrical connections and enhances the overall efficiency of the cryogenic FPA system.
Implementation Method 1
An optical-to-electrical (O/E) converter converts the optical power signal into an electrical power signal
Implementation Method 2
An IR optical detector array (ODA) receives light through the main optical window and converts the light into a plurality of detected electrical charges
Implementation Method 3
The evacuated chamber and double-walled construction resist irradiant thermal energy exchange with the surrounding air
Implementation Method 4
Cryocoolers such as those based on a Stirling refrigeration cycle are well known in the relevant art
Data Source
AI summary
An optically powered cryogenic FPA with an optical data link eliminates electrical penetrations of the cryogenic chamber for power delivery thereby reducing heat leaks into the cold volume by copper wires and EMI. An optical splitter receives and separates an optical input signal into an optical carrier signal, an optical Data IN signal and an optical power signal. An optical-to-electrical (O/E) converter converts the optical power signal into an electrical power signal, which is converted into a plurality of DC voltage signals to supply power within the chamber. An optical data link modulates the optical carrier signal with electrical signals from the ROIC to form and output an optical Data OUT signal.