Eye-Safe Laser Sensor Detector Array Readout Circuit
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Solution Overview
Problem
Conventional laser guidance systems pose eye safety risks due to non-eye safe lasers and are costly when using gimbaled sensors for eye-safe wavelengths, while body-fixed sensors with existing detector materials cannot effectively detect eye-safe lasers without large arrays or scanning mechanisms.
Innovation Solution
A multi-element detector array with InGaAs or HgCdTe detector elements grouped into subsets, coupled with a readout circuit that generates both four-quadrant compatible and individual detector element outputs, allowing for accurate angle measurement and wide field of view without the need for gimbals or large arrays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional silicon detectors are used in body-fixed sensors, then the sensor structure is simple and low cost, but the detector cannot respond to eye-safe laser wavelengths (1.54 μm)
Solution Approach 1:
The patent changes the detector material parameter from conventional silicon to InGaAs or HgCdTe, which have different bandgap properties that enable response to longer eye-safe wavelengths (1.54 μm) while maintaining detector functionality
2Reliability
If InGaAs or HgCdTe detectors are used to detect eye-safe lasers, then the detection capability for eye-safe wavelengths is achieved, but the detector must be very small due to high capacitance, preventing wide field of view without large arrays or scanning mechanisms
Solution Approach 1:
The patent divides the detector into multiple small elements arranged in an array configuration. Each element has the required small size for InGaAs/HgCdTe material properties, but the collective array provides a wide field of view equivalent to a much larger single detector
3Area of stationary object
If a large array of InGaAs or HgCdTe detectors is used to achieve wide field of view, then the field of view is sufficient, but the device complexity and cost increase significantly
Solution Approach 1:
The patent combines multiple small detector elements into a unified array structure with integrated readout electronics. The elements work together as a single functional unit, providing wide field of view capability while maintaining manageable complexity through standardized configuration and processing
4Measurement precision
If a gimbaled sensor is used to provide wide field of view with eye-safe detectors, then high angle measurement accuracy and wide field of view are achieved, but the cost becomes very high
Solution Approach 1:
The patent replaces the mechanical gimbal system with a body-fixed detector array configuration. The wide field of view and angle measurement capabilities are achieved through the spatial arrangement of detector elements and signal processing algorithms rather than mechanical movement, eliminating gimbal complexity and cost
5Reliability
If non-eye safe lasers (1.06 μm) are used in laser guidance systems, then the laser technology is well-established and effective, but friendly forces and non-combatants are at risk of eye damage
Solution Approach 1:
The patent changes the laser wavelength parameter from 1.06 μm (non-eye-safe) to 1.54 μm (eye-safe). This wavelength change moves the laser operation to a region where the human eye's lens focuses less energy on the retina, reducing eye damage risk while maintaining laser guidance effectiveness through appropriate detector selection
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
The solution enables eye-safe laser detection with improved angle measurement accuracy and cost-effectiveness, compatible with existing four-quadrant guidance systems, while reducing eye safety risks and operational costs.
Implementation Method 1
Newer detector materials such as InGaAs or HgCdTe will respond to eye-safe laser wavelengths
Data Source
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Figure 3a~4
Figure 5a
AI summary
A sensor for laser spot trackers. The novel sensor includes a detector array comprised of a predetermined number of subsets, each subset including a plurality of detector elements, and a readout circuit for providing a first output and a second output, the first output including subset signals that represent the total energy received in each subset and the second output including signals representing energy received by each individual detector element. In an illustrative embodiment, the array is divided into four subsets and the first output includes four subset signals that are compatible with four- quadrant guidance systems. A subset signal is generated by thresholding signals received from each individual detector element to remove noise, and then summing the thresholded signals from each detector element in the subset.