Apparatus and method to perform per-pixel microbolometer camera time constant measurements
AssigneeThe United States of America as represented by the Secretary of the Army
InventorsDennis L. Waldron, Rolf-Dieter J. Lohrmann
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Abstract
An apparatus to measure the time constant of microbolometer-type uncooled thermal imaging camera pixels on a per-pixel basis has been developed. The apparatus utilizes a longwave infrared laser and acousto-optic modulator as a periodic light source to excite the pixels of the camera's focal plane array. The image frames captured by the camera during excitation are then processed and the data fit using the algorithms developed to find the time constant for each pixel in the array.
Claims22
An apparatus for gathering appropriate data from which TC can be extracted for each pixel, comprising:
- a laser source to output a source laser beam;
- a closed loop laser line tracker disposed to stabilize the laser source;
- an AOM with radio frequency driver disposed to modulate the source laser beam into orders −1, 0, and 1 laser beams, wherein said order 1 laser beam is the desired modulated beam and orders −1 and 0 laser beams are undesired laser beams;
- a waveform generator to provide a square wave control to the AOM modulating the source laser beam;
- a beam block to block the undesired order −1 and 0 laser beams;
- a collimating beam expander to appropriately size the order 1 laser beam;
- a beam expander to expand the order 1 laser beam as an expanded beam larger than the input of the camera;
- a camera device under test directed to image said expanded beam and output a camera digital signal;
- a video splitter to replicate and split the camera digital signal into a digital video signal and other data stream;
- a DVR to record the digital video signal and output digital video frames;
- a time tagger device to generate timestamps for each data frame of other data stream;
- a clock pulse generator to provide an accurate time reference signal to the time tagger device to generate timestamps;
- a frequency standard to discipline the clock pulse generator and said waveform generator;
- and
- a PC to process data generated from said digital video frames and timestamps.
Dependencies are inferred from the claim text.