Rolling-Shutter CMOS Laser Impact Imaging for PRI Estimation
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Solution Overview
Problem
Existing guided munitions rely on Indium gallium arsenide (InGaAs) CMOS sensors for visualizing laser pulse impacts, which do not allow for the determination of pulse repetition period (PRI), increasing complexity, size, power consumption, and cost due to the need for additional avalanche photodiodes.
Innovation Solution
A method and device using a silicon CMOS type optronic sensor with a rolling shutter readout circuit and electronic image processing circuit to visualize laser pulse impacts and estimate PRI by exploiting the readout phase shift between sensor lines, allowing for detection of transition points in image frames.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If InGaAs CMOS sensors are used to visualize laser pulse impacts, then visualization capability is achieved, but the ability to determine pulse repetition period is lost
Solution Approach 1:
The patent introduces an intermediary mechanism - the rolling shutter readout circuit's time-dependent line-by-line exposure - that enables PRI determination through the existing CMOS sensor without requiring additional specialized detectors. The sequential reading of lines creates a time-stamped record of laser spot position that serves as an intermediary for extracting repetition period information.
Solution Approach 2:
The patent replaces the need for complex additional detection hardware (avalanche photodiodes) with a software-based analysis of the rolling shutter readout data. The mechanical/physical complexity of adding specialized sensors is substituted by computational processing of the existing sensor's temporal exposure patterns.
2Measurement precision
If avalanche photodiodes are added to detect PRI, then pulse repetition period determination is enabled, but device complexity, size, power consumption, and cost increase
Solution Approach 1:
The patent makes the rolling shutter readout circuit serve multiple functions: its primary function of reading sensor data is combined with a secondary function of providing temporal information for PRI determination. This multi-functionality eliminates the need for dedicated PRI detection hardware, reducing overall device complexity while maintaining measurement capability.
Solution Approach 2:
The existing rolling shutter readout circuit inadvertently provides the temporal information needed for PRI determination without requiring additional components. The system essentially serves itself - the necessary timing information is already embedded in the readout process, and software analysis extracts this information without needing separate detection hardware.
3Measurement precision
If avalanche photodiodes are added to detect PRI, then pulse repetition period determination is enabled, but device size increases
Solution Approach 1:
The patent extracts the PRI determination capability from the physical hardware domain and relocates it to the software/data processing domain. By taking out the need for additional physical detectors and implementing the functionality through analysis of existing readout data, the device size is reduced while maintaining the measurement capability.
4Measurement precision
If avalanche photodiodes are added to detect PRI, then pulse repetition period determination is enabled, but power consumption increases
Solution Approach 1:
The rolling shutter readout circuit's power consumption remains unchanged as it continues its standard operation. The PRI determination is achieved by analyzing the data already being collected during normal sensor operation, eliminating the need for additional power-hungry detection hardware while maintaining full functionality.
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 simple, reliable, and cost-effective visualization and estimation of laser pulse repetition period without the need for additional components, reducing complexity and cost while maintaining accuracy.
Implementation Method 1
a silicon CMOS type optronic sensor having a predetermined number of lines, a 'Rolling Shutter' type reading circuit
Implementation Method 2
an optronic sensor (1) of the CMOS type having a predetermined number of lines (Z), a reading circuit (2) of the 'Rolling Shutter' type
Implementation Method 3
laser pulses emitted by a laser designator
Implementation Method 4
a signal resulting from a reflection of one of the laser pulses
Data Source
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AI summary
Method for visualising impacts of laser pulses emitted by a laser designator, according to a predetermined repetition interval (PRI), onto a target present in a scene, by means of a device comprising: an optronic sensor of the silicone-based CMOS type having a predetermined number of rows associated with a rolling shutter-type readout circuit. Each row of the sensor is exposed for an exposure time and read during a reading time so that the exposure time is no less than the reading time but no more than the product of the reading time and the number of rows. A transition between the rows exposed to a signal and the rows not exposed to said signal is detected in at least two images in order to infer the PRI.