Method and apparatus for correction of microbolometer output
First Claim
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1. A method of correcting the output of a microbolometer detector system, said method comprising:
- providing a microbolometer detector system for operation in an ambient temperature range, said microbolometer detector system further comprising at least one microbolometer detector, and an apparatus for reducing thermal noise;
providing a temperature stabilization system for correcting the temperature variation of the microbolometer detector;
providing an electronic system for conditioning the output of the microbolometer detector wherein the electronic system;
responds to variations in a radiant flux signal from a source;
modulates the sensitivity of the microbolometer detector to the variations in the radiant flux signals;
converts the output from the microbolometer detector from an analog signal to a digital signal using an analog-to-digital converter; and
limits the output from the microbolometer detector so that the microbolometer detector output remains within an input sensitivity range of the analog-to-digital converter; and
applying a correction factor to the output signal of the microbolometer detector.
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Abstract
A method and apparatus for correction of temperature-induced variations in the analog output characteristics of a microbolometer detector in an infrared detecting focal plane array utilizing electronic means to correct for the temperature variation of the individual microbolometer detector. The electronic circuitry and associated software necessary for implementation is also described.
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Citations
26 Claims
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1. A method of correcting the output of a microbolometer detector system, said method comprising:
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providing a microbolometer detector system for operation in an ambient temperature range, said microbolometer detector system further comprising at least one microbolometer detector, and an apparatus for reducing thermal noise;
providing a temperature stabilization system for correcting the temperature variation of the microbolometer detector;
providing an electronic system for conditioning the output of the microbolometer detector wherein the electronic system;
responds to variations in a radiant flux signal from a source;
modulates the sensitivity of the microbolometer detector to the variations in the radiant flux signals;
converts the output from the microbolometer detector from an analog signal to a digital signal using an analog-to-digital converter; and
limits the output from the microbolometer detector so that the microbolometer detector output remains within an input sensitivity range of the analog-to-digital converter; and
applying a correction factor to the output signal of the microbolometer detector. - View Dependent Claims (2, 3)
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4. A method of correcting the output of a microbolometer detector system, said method comprising:
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providing a microbolometer detector system for operation in an ambient temperature range, said microbolometer detector system further comprising at least one microbolometer detector, and an apparatus for reducing thermal noise;
said apparatus for reducing thermal noise being selected from the group consisting of a lens, a dewar window, and a cold shield;
providing a temperature stabilization system for correcting the temperature variation of the microbolometer detector;
providing an electronic system for conditioning the output of the microbolometer detector; and
applying a correction factor to the output signal of the microbolometer detector wherein applying the correction factor to the output signal of the microbolometer detector decreases effects of temperature variations in the lens, dewar window, or cold shield.
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5. A method of correcting the output of a microbolometer detector system, said method comprising:
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providing a microbolometer detector system for operation in an ambient temperature range, said microbolometer detector system further comprising at least one microbolometer detector, and an apparatus for reducing thermal noise;
providing a temperature stabilization system for correcting the temperature variation of the microbolometer detector;
providing an electronic system for conditioning the output of the microbolometer detector wherein the electronic system performs an algorithm to calculate a corrected offset value based on the difference between an individual microbolometer detector temperature and a baseline temperature; and
applying a correction factor to the output signal of the microbolometer detector. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of correcting the output of a microbolometer detector system, said method comprising:
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providing a microbolometer detector system for operation in an ambient temperature range, said microbolometer detector system further comprising at least one microbolometer detector, and an apparatus for reducing thermal noise;
providing a temperature stabilization system for correcting the temperature variation of the microbolometer detector;
providing an electronic system for conditioning the output of the microbolometer detector;
providing a system for varying the responsivity of the microbolometer;
applying a correction factor to the output signal of the microbolometer detector. - View Dependent Claims (16, 17, 18, 19, 20)
adjusting the sampling time, bias voltage, or degree of mechanical vignetting;
recording the resulting analog offset values which satisfy the requirement that the output of the microbolometer detector be well matched to the input sensitivity range of a analog-to-digital converter; and
curve fitting the results.
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19. The method of claim 18, further comprising the step of applying an analog offset correction factor.
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20. The method of claim 18, further compensating for variations in the temperature of system components, said steps comprising:
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providing temperature sensors operationally connected to said system components;
monitoring said temperature sensors;
correlating system component temperatures with an analog offset voltage required to bring said microbolometer detector output to the approximate center of the input sensitivity range of the analog-to-digital converter;
curve fitting the correlated system component temperatures and the analog offset voltages; and
producing at least one mathematical function of analog offset voltage vs. system component temperature.
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21. An apparatus for correction of a microbolometer detector output, said apparatus comprising:
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at least one microbolometer detector;
a thermal noise reduction system operationally connected to said at least one microbolometer detector;
an electrical reference circuit connected to said at least one microbolometer detector;
an output from said electrical reference circuit connected to an input of a signal conditioning circuit wherein the signal conditioning circuit further comprises;
a differential amplifier;
a first reference source;
a signal processor;
an output from said electrical reference circuit connected to a first input of said differential amplifier;
an output from said first reference source connected to a second input of said differential amplifier; and
an output from said signal processor connected to said first reference source, wherein the output of the first reference source is determined by the signal processor; and
an output from said signal conditioning circuit connected to a display device. - View Dependent Claims (22, 23, 24)
a temperature sensor operationally connected to said microbolometer;
a second reference source operationally connected to said temperature sensor;
an analog-to-digital converter operationally connected to said temperature sensor, said second reference source, and to said signal processor.
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23. The apparatus of claim 21, wherein the first reference source is a voltage source.
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24. The apparatus of claim 23, wherein the voltage source is a digital-to-analog converter.
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25. An apparatus for correction of a microbolometer detector output, said apparatus comprising:
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at least one microbolometer detector;
a thermal noise reduction system operationally connected to said at least one microbolometer detector;
an electrical reference circuit connected to said at least one microbolometer detector;
an output from said electrical reference circuit connected to an input of a signal conditioning circuit wherein the signal conditioning circuit contains an algorithm to calculate a corrected offset value based on the difference between an individual microbolometer detector temperature and a baseline temperature; and
an output from said signal conditioning circuit connected to a display device. - View Dependent Claims (26)
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Specification