Geiger-mode Ladar Frame Rate Optimization via Resonance Removal
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Solution Overview
Problem
Framed Geiger-mode LADAR systems face challenges in achieving high sensitivity due to resonances, which reduce the ability to detect weak return signals, leading to blind spots and gaps in data, and requiring increased laser power, complicating signal processing and calibration.
Innovation Solution
The implementation of signal processing circuitry that selects an initial frame rate to maximize sensitivity of a Geiger-mode Avalanche Photodiode (GmAPD) detector and adjusts it to reduce and/or remove system resonances, determining a final optimal frame rate for processing LADAR pulse returns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the frame rate is increased to improve detection sensitivity, then the ability to detect weak return signals improves, but system resonances cause sensitivity reduction at certain wavelengths
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the frame rate of the Geiger-mode LADAR system based on detected resonance conditions. When resonances are detected at specific frame rates, the system changes the frame rate parameter to avoid these resonant frequencies, thereby maintaining consistent detection sensitivity across different operating conditions and eliminating blind spots in the detection spectrum.
2Measurement precision
If laser power is increased to compensate for sensitivity loss, then detectable return signals improve, but system size, cost and heat increase
Solution Approach 1:
The patent changes the operational parameter (frame rate) to avoid resonance-induced sensitivity losses rather than compensating with increased laser power. This approach maintains signal detectability while avoiding the need for higher power lasers, thereby preventing increases in system size, cost, and heat generation.
Solution Approach 2:
The patent replaces the mechanical approach of increasing laser power with a control system approach that dynamically adjusts frame rate based on resonance detection. This substitution uses software/control logic instead of hardware scaling, avoiding the physical consequences of increased system size and power consumption.
3Measurement precision
If frame rate is adjusted to remove resonances, then sensitivity is improved, but clustering of pulse returns occurs
Solution Approach 1:
The patent applies dynamics by making the frame rate adjustable and adaptive rather than fixed. The system dynamically changes the frame rate based on real-time resonance conditions, allowing it to optimize between sensitivity and pulse return distribution. This dynamic adjustment enables the system to maintain uniform pulse spacing when resonances are present while preserving high detection sensitivity.
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 results in improved sensitivity for framed Geiger-mode LADAR systems, potentially increasing detection capabilities by up to 20% or more, while minimizing clustering of pulse returns and maintaining optimal frame rates.
Implementation Method 1
Framed Geiger-mode LADAR systems use an avalanche photodiode operated above its breakdown voltage so that a single photon detection can trigger a large electrical pulse allowing for high sensitivity
Data Source
AI summary
A framed Geiger-mode laser detection and ranging (LADAR) system includes signal processing circuitry configured to select an initial frame rate to maximize sensitivity of a Geiger-mode Avalanche Photodiode (GmAPD) detector. The signal processing circuitry may adjust the initial frame rate to reduce and/or remove system resonances to determine a final (i.e., more-optimal) frame rate. The signal processing circuitry may process LADAR pulse returns using the final frame rate. The initial frame rate may be an initial optimal anti-blocking frame-rate determined from a background rate of the LADAR system, a read-out period of the GmAPD detector, and the Lambert W function. The initial frame rate may be adjusted to remove resonances using an Nth order Farey sequence to determine the final frame rate.