Research On Broad Spectrum Testing Technology Based On Grating Multiplexing

Spectral responsivity refers to the voltage response or current response generated when light radiation of different wavelengths is irradiated on the detector,and is an important parameter for evaluating the performance of the detector.In-depth researches on the detector's spectral testing technology and the improvement of the theoretical system of spectral testing can improve the performance of the detector.This thesis mainly explores the wide-spectrum testing technology based on monochromator to realize grating multiplexing.The built spectral response test system has realized a wide test range and high resolution relative spectral response test.This paper mainly introduces the research content from the following aspects:(1)On the premise of in-depth study of the four commonly used detector spectral response testing methods of broadband filter method,standard replacement method,direct comparison method,and Fourier transform method,a new spectral test method based on monochromator is proposed.This method adopts the idea of standard alternative method and builds a high-resolution and wide-spectrum spectrum test system based on grating multiplexing.(2)In order to remove the interference of the surrounding environment on the signal,based on the principle of Fourier transform,a chopper is used to modulate the radiation signal,and then the collected data is demodulated to ensure the accuracy of the test results.(3)By studying the working principle of the monochromator,design experiments to analyze the influence of the width of the entrance slit of the monochromator on the resolution of the instrument,and draw the following conclusions: as the width of the entrance slit increases,the half-height width of the corresponding wavelength increases,The light flux increases,the center wavelength shifts to the long wave direction,and the resolution of the monochromator decreases accordingly.This conclusion provides a basis for balancing the flux and resolution of the instrument.(4)On the basis of the theory of diffraction,deeply understand the principle of the blazed grating in the monochromator.Because the exit wavelength of the monochromator has a certain bandwidth,the paper innovatively proposes to construct a model in the case of a large exit slit width(such as a 2.5mm exit slit)and use algorithm processing to restore the reality spectrum.(5)According to the formula corresponding to the light intensity diffraction pattern derived in this paper,it is found that there is strong light radiation near the center of the first-order blaze wavelength,and its intensity gradually decreases along both ends.Based on this phenomenon,it is proposed that the wavelength point of the switching grating should be located in the middle of the blazed wavelength of the two gratings,and that the switching point should not select the abrupt point,thereby realizing grating multiplexing and expanding the test range of the spectrum test system.(6)In terms of data processing,the data is pre-processed using a hybrid method of quadratic sequential filtering and median filtering to select pixels that can characterize the spectral characteristics of the detector.In the process of data collection,the Grubbs criterion is used to eliminate abnormal data.Finally,MATLAB is used to perform spline interpolation on the collected data to smooth the data curve,and to obtain the curve segmentation function,which plays the role of predicting the response value of a specific wavelength.