Synchronous Detecting System Of Working Parameters Of Spectrometer

The stability is an important index of spectral instrument, and it has many influence factors. A synchronous monitoring system for working parameter of spectrometer was designed to meet requirements of stability analysis of self-made near infrared spectrometer PISA-S. The system provided the basis for confirming the stability influence factor and improving the stability of spectrometer.According to the structure and operation process of the PISA-S spectrometer,this paper analyzes the factors affecting spectrometer stability and determines parameters and indicators.Synchronous detecting system is designed by using the STM32 microcontroller and PC control, realizing real-time simultaneous multi-parameter monitoring, data logging, analysis and storage.The system has three parts including NIRlight source detecting module, sensor refrigeration detecting moduleand signal demodulation detecting module, and each module uses STM32 microcontroller as the bottom controller. It makes communication with the host computer through the serial port to transmit data and instructions.The light source detecting module included the voltage/current sampling unit, the analog to digital conversion unit and illumination and temperature measurement unit. The supply voltage, supply current, illumination and environment temperature were measured by the microcontroller and computer. The sensor refrigeration detecting module included the impedance matching unit and the analog to digital conversion unit. The thermistor of sensor was measured to calculate the refrigeration temperature by the microcontroller.The signal demodulation detecting module includes signal wave-shaping unit and signal measurement unit,the processed detection signal by signal wave-shaping unit and the reference signal were transmitted to the interfaces of microcontroller, microcontroller achieved the frequency,duty ratio and phase difference of detection signa and reference signal by the capture function of timing counter.Synchronous detecting system got spectrometer operation signal to achieve simultaneous measurement.The results of system test and experiment shown that the synchronous monitoring system realized synchronous measuring of the supply voltage, supply current, illumination and environment temperature of light source, the refrigeration temperature of sensor, the frequency, duty cycle and phase difference of measured signal and reference signal. The design indexes were satisfied in the synchronous monitoring system.