Design Of Weak Signal Detection System Of HgCdTe Infrared Detector

The thermal diffusivity is one of the important parameters ofthermophysical properties of materials characterization, has importantsignificance for structural design of aerospace aircraft and weapons of certain keycomponents. The infrared detection technology is more and more applications inthe thermal diffusivity of the aerospace material measuring device, where the weaksignal detection based on infrared detector is an important part of thermal diffusivitymeasurement device, the quality of the design of weak signal detection system basedon infrared detectors has a direct impact on accuracy of the thermal diffusivitymeasurement.In this paper, the space thermal diffusivity measurement technology as theresearch background, design to a small signal detection and acquisition system basedon HgCdTe infrared detector. Because infrared detection output signal is extremelyweak, easily submerged in noise, so in the design of the whole system havehighlighted the technique of weak signal detection, restrain noise and improve signalnoise ratio of the whole system. The hardware part, a reasonable signal conditioningcircuit is designed, The output signal from channel board through A/D conversion ofthe digital acquisition card DaqBook200into the PC. Software part adopts VC++towrite, using the method of software filtering the weak signal, to realize the signalreal-time detection, acquisition and display, and provides support for the next step ofmeasurement of thermal diffusivity.This paper focuses on the design and analysis of small signal acquisition systembased on the HgCdTe infrared detector in the space of thermal diffusivity ofmeasurement technology, the specific contents are as follows:1Through the analysis and research of related data, summarizes the backgroundand the actual significance of this paper, and researched the principle of measurement of thermal diffusivity by laser pulse;2The paper put forward the overall scheme of weak signal detection system,analyzes the energy conversion of infrared detector, and the choose ofHgCdTe infrared detector. Based on the principles of the high common moderejection ratio, high signal-to-noise ratio, high sensitivity and strong anti interferenceability, the hardware design of the specific detection circuit based on the HgCdTeinfrared detector, including filter processing in power supply module, using highspeed and high accuracy, low noise instrumentation amplifier, and to achieve thedesign of hardware with differential amplification circuit. the software usingmultithreading programming model, completed interface design of signal acquisitionand display, signal digital acquisition card DaqBook200acquisition and display onPC;3Debugging and calibration laboratory experiment, repeated measurementsobtain the measured experimental data, analysis of the effect of error sources of thesystem through the experimental result, assessment of accuracy and the reliability ofthe whole system.