Multi-band focal plane array with integrated visible and infrared detectors
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Solution Overview
Problem
Current focal plane arrays are limited in simultaneous multi-band detection, primarily operating within the infrared range and requiring cryogenic cooling, which restricts their effectiveness for day and night surveillance and reconnaissance applications.
Innovation Solution
A multi-band focal plane array architecture that integrates visible and infrared detectors in a checkerboard pattern or alternate rows/columns, using silicon and IV-VI based photon detectors, allowing simultaneous detection across visible and short/medium infrared wavelength bands without cryogenic cooling, and utilizing flip-chip bonded readout circuits for enhanced resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single focal plane array is used for multi-band detection, then the detection capability across multiple spectral ranges is improved, but the device complexity and cooling requirements increase
Solution Approach 1:
The focal plane array is segmented into distinct detector regions, each optimized for specific wavelength bands. The array includes first detectors for long-wavelength infrared, second detectors for medium-wavelength infrared, and third detectors for short-wavelength infrared, allowing each segment to operate independently at different temperature ranges without requiring uniform cryogenic cooling across the entire array.
Solution Approach 2:
Different regions of the focal plane array are assigned different thermal characteristics and detector types based on local detection requirements. Long-wavelength detectors are positioned in regions with better thermal isolation, while short-wavelength detectors can operate at higher temperatures, allowing optimized performance for each wavelength band without compromising the entire system.
2Measurement precision
If cryogenic cooling is used for infrared detection, then the detection sensitivity is improved, but the system complexity and cost increase
Solution Approach 1:
The detector array is divided into multiple groups with different cooling requirements. Only the long-wavelength infrared detectors require cryogenic cooling to achieve high sensitivity, while medium and short-wavelength detectors can operate at higher temperatures, significantly reducing the overall cooling system complexity and cost.
Solution Approach 2:
The operating temperature parameter is optimized differently for each detector type based on its wavelength sensitivity requirements. Long-wavelength detectors operate at cryogenic temperatures (77K or lower) for maximum sensitivity, while medium and short-wavelength detectors operate at progressively higher temperatures, eliminating the need for uniform extreme cooling across all detectors.
3Measurement precision
If separate focal plane arrays are used for different wavelength bands, then the detection precision for each band is improved, but the system complexity increases
Solution Approach 1:
Multiple detector types with different wavelength sensitivities are merged into a single focal plane array structure. The array integrates long-wavelength infrared detectors, medium-wavelength infrared detectors, and short-wavelength infrared detectors in one unified device, maintaining band-specific detection precision while reducing system complexity compared to using separate arrays for each wavelength band.
Solution Approach 2:
The focal plane array is designed as a multi-functional device that can detect across multiple wavelength bands simultaneously. Each detector element is optimized for specific wavelength ranges, but the entire array functions as a universal surveillance system capable of operating across the full infrared spectrum without requiring separate specialized arrays.
4Adaptability or versatility
If visible and infrared detectors are integrated, then the simultaneous day and night detection capability is improved, but the manufacturing complexity increases
Solution Approach 1:
Visible light detectors and infrared detectors are merged into a single focal plane array structure with unified readout electronics and control systems. The array uses consistent fabrication processes and materials where possible, integrating different detector types in a standardized architecture that simplifies manufacturing compared to assembling separate visible and infrared systems.
Solution Approach 2:
The integration approach adds a spectral dimension to the detector array by incorporating multiple wavelength-sensitive detector types within the same physical structure. Rather than stacking detectors in three dimensions, the array uses a two-dimensional layout where different detector types are positioned in specific regions, allowing simultaneous visible and infrared detection without excessive manufacturing 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
Enables simultaneous detection of visible and infrared light across multiple bands, improving detection probability and reducing false alarms, while eliminating the need for cryogenic cooling, thus simplifying and cost-reducing the system.
Implementation Method 1
The first detector includes a visible detector such as a CMOS detector or a CCD detector, while the second detector includes an IR detector operative to detect short or medium wavelength infrared light
Implementation Method 2
As the visible detector is transmissive to the IR wavelength range, the light will transmit through the visible detector and incident on the IR detector
Data Source
AI summary
A multi-band focal plane array architecture operative to detect multiple spectral image. The multi-band focal plane array architecture has an integrated readout circuit, a plurality of first detectors integrated in the readout circuit and a plurality of second detectors deposited on the readout circuit. Preferably, the first detectors are operative to detect visible signals and the second detectors are operative to detect infrared signals. The first and second detectors are arranged in a checkerboard pattern, in alternate rows or columns, or at least partially overlapped with each other to realize simultaneous detection in two different wavelength bands. The architecture may also have an additional integrated readout circuit flip-chip bonded to the integrated readout circuit. By forming a plurality of third detectors on the additional integrated readout circuit, a tri-band focal plane array may be realized. In one embodiment, a dual-band focal plane array architecture by forming two arrays of detectors on two individual integrated readout circuit and flip-chip bonding these two readout circuits.