Computer implemented method for detecting short pulse lasers
AssigneeThe Secretary of State for Defence
InventorSean Michael Tsi-Ong Tipper
Life of this patent
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Abstract
The present application relates to the field of detecting pulsed radiation, in particular to methods and apparatus suitable for use in detecting short pulse lasers and extracting their pulse repetition frequencies, and especially an improved computer implemented method for detecting a pulse repetition frequency of pulsed radiation using a sensor array of sensor elements arranged in element lines.
Claims21
A computer implemented method for detecting a pulse repetition frequency of pulsed radiation using a sensor array of sensor elements arranged in element lines, the method comprising the steps of:
- a) addressing the sensor array of sensor elements using a rolling shutter operation, wherein the rolling shutter operation comprises addressing each element line consecutively for a predetermined integration period;
- b) reading the sensor array to obtain a radiation image, the radiation image comprising a plurality of pixel values, with each pixel value corresponding to a sensor element in the sensor array;
- and then
- c) applying a pulse detection operation to the radiation image to detect a pulse repetition frequency of the pulsed radiation;
- wherein the step of applying the pulse detection operation comprises the steps of:
- d) extracting a beat signal from the pixel values of the radiation image in a sensor array direction corresponding to the direction of the rolling shutter operation;
- e) calculating a beat frequency of the beat signal;
- f) calculating a peak to trough ratio of the beat signal;
- g) calculating a value for a pulse shape parameter of the beat signal;
- and then
- h) calculating a pulse repetition frequency of the pulsed radiation using a pulse repetition frequency function, the pulse repetition frequency being a function of the beat frequency, peak to trough ratio and pulse shape parameter.
A non-transitory computer-readable medium storing computer-executable instructions, wherein when executed by a processing device, cause the processing device to perform operations comprising:
- addressing a sensor array of sensor elements using a rolling shutter operation, wherein the rolling shutter operation comprises addressing each element line consecutively for a predetermined integration period;
- reading the sensor array to obtain a radiation image, the radiation image comprising a plurality of pixel values, with each pixel value corresponding to a sensor element in the sensor array;
- and
- applying a pulse detection operation to the radiation image to detect a pulse repetition frequency of pulsed radiation, wherein applying the pulse detection operation comprises:
- extracting a beat signal from the pixel values of the radiation image in a sensor array direction corresponding to the direction of the rolling shutter operation;
- calculating a beat frequency of the beat signal;
- calculating a peak to trough ratio of the beat signal;
- calculating a value for a pulse shape parameter of the beat signal;
- and
- calculating a pulse repetition frequency of the pulsed radiation using a pulse repetition frequency function, the pulse repetition frequency being a function of the beat frequency, peak to trough ratio and pulse shape parameter.
Dependencies are inferred from the claim text.