The Infrared Detector Uses The Noise Measurement Of The Bias Voltage Source

Infrared imaging system utilizes optical system and infrared detector to receive the infrared radiation of the target object and handle the infrared radiation distribution with the way of visible to human.The functions of the imaging processing circuit include providing power supply,bias voltage and drive signal for detector.The weakest infrared radiation signal that an infrared imaging system can detect is limited by its noise.The noise of bias voltage source will introduce noise to the output of detector,and increase the NETD of the system and reduce the system performance.At present,there are many researches on the design of bias voltage source for infrared detectors,but there is almost no research for accurate noise measurement of bias voltage sources.Generally,the quality of the bias source is only judged by the imaging quality,Therefore,it is important and necessary to study the noise measurement of the bias voltage source for infrared detectors.The main research content of this article is as follows:1.The article investigated the technical literature,proceeded from the noise in the infrared imaging system,focused on analyzing the specific effects of the bias voltage source for the infrared detector,summarized the research status and problems of the bias voltage source,and demonstrated the research status of the bias voltage source noise measurement.2.By studying the fundamental theory of noise,the paper summarizes the principle of noise measurement adopted in this paper.The preamplifier circuit and the filter circuit of the low-frequency noise measurement circuit were designed,and the device selection and function simulation were performed respectively,verifying the correctness of the noise measurement system.3.The article uses two schemes to design the bias voltage source for infrared detectors.One is to apply a voltage reference to divide the voltage,then filter and buffer to get the bias voltage;the other is to use a linear regulator to generate the bias voltage.4.Based on the hardware implementation of low noise bias voltage source circuit and noise measurement circuit,the low-frequency noise measurement device was used to measure and compare the low-frequency noise of the four bias voltage circuits.The experimental results show that the low-frequency noise measurement device can effectively measure the noise value of the bias voltage under the current laboratory conditions,so as to select the bias source scheme with lower noise.After processing and analyzing the noise data,provide guidance to the bias voltage generation circuit: a scheme based on the voltage reference to generate the bias voltage is feasible,but in order to avoid the amplifier introducing large noise,the equivalent current noise of the op amp should be unavoidably considered.