Optical Pulse Detection Device Using Adjustable Frequency Filters
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Solution Overview
Problem
Conventional optical pulse detection systems face challenges in accurately detecting short-duration pulses, such as laser pulses, due to high false alarm rates caused by parasitic solar flux and imprecise angular localization, especially with four-quadrant detectors and imaging matrix detectors.
Innovation Solution
A detection device comprising a sensor with multiple pixels, each equipped with a receiver generating electrical signals, an event detection unit with adjustable frequency filters, and a chronometry unit, allowing for precise detection of short pulses by filtering out noise and accurately localizing the emission source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If four-quadrant detectors with large bandwidth are used, then detection of very short pulses is improved, but sensitivity is reduced due to daytime noise and localization precision deteriorates outside the center
Solution Approach 1:
The detector is divided into multiple independent pixels arranged in a matrix, where each pixel operates as an independent detection element with its own event detection unit and frequency filter. This segmentation allows parallel processing of optical signals across multiple spatial locations, maintaining high bandwidth for short pulse detection while reducing the impact of noise through spatial distribution.
Solution Approach 2:
Each pixel incorporates an event detection unit with adjustable frequency filters that can dynamically adapt the bandwidth characteristics. The event detection unit detects variations in electrical signals only when their frequency falls within the adjustable bandwidth, allowing optimization between detecting very short pulses and rejecting longer duration noise events on demand.
2Measurement precision
If imaging matrix detectors are used, then localization precision is improved, but false alarm rate increases due to long integration times that cannot distinguish short laser pulses from longer solar reflections
Solution Approach 1:
The event detection unit in each pixel incorporates adjustable frequency filters that can be configured to detect only specific frequency ranges corresponding to short-duration optical pulses. By setting the bandwidth characteristics appropriately, the system can distinguish between short laser pulses and longer solar reflections, maintaining precise localization while reducing false alarms from integrated noise.
Solution Approach 2:
The system changes the temporal integration parameter by using event detection based on frequency-filtered signal variations rather than long integration times. This allows the detector to respond to rapid optical pulse events while ignoring slower solar reflection events, achieving both precise localization and reduced false alarm rates through parameter optimization.
3Use of energy by moving object
If long integration times are used in imaging matrix detectors, then signal accumulation is improved, but the ability to distinguish short events from longer events deteriorates
Solution Approach 1:
The event detection unit uses adjustable frequency filters to dynamically control the temporal response characteristics. By configuring the bandwidth to pass only high-frequency variations corresponding to short-duration pulses, the system achieves effective signal accumulation for laser pulses while automatically rejecting lower-frequency solar reflection events, thus improving event discrimination capability.
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 device effectively detects short-duration optical pulses with high precision, reducing false alarms and enabling precise angular localization of the emission source, while rejecting longer duration events like solar reflections.
Implementation Method 1
a receiver configured to receive optical pulses and to generate an electrical signal having variations representative of the received optical pulses
Data Source
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AI summary
The present invention relates to a device for detecting optical pulses, the device comprising a sensor (20) having a plurality of pixels, each pixel comprising: - a receiver configured to receive optical pulses and to generate an electrical signal; - an event detection unit comprising a frequency filter having an adjustable cutoff frequency defining a bandwidth for the event detection unit, the adjustable cutoff frequency being such that the upper limit of the bandwidth is higher than or equal to 1 megahertz, the detection unit being configured to detect the variations in the electrical signal generated by the receiver only when the frequency in the frequency domain of said variations is within the bandwidth of the event detection unit; and - a time-measuring unit configured to date each variation of the electrical signal detected by the event detection unit.