光电探测器阵列光敏元宽度对谱线峰值位置影响的研究

本文针对采用光电阵列探测器进行信号采集的光谱分析系统,分析了探测器阵列光敏元宽度对光谱峰值定位的影响.指出由于光敏元具有一定宽度,导致非对称型光谱峰值的亚象元定位误差,并提出用反卷积消除这种误差.

INFLUENCES ON SPECTRUM LINE POSITION CAUSED BY LIGHT ACTIVATED ELEMENT'S WIDTH OF ELECTROPHOTONIC ARRAY

Electrophotonic detector array,such as CCD,has been used in various micro spectrometers,for it can easily collect all signals in working spectra range simultaneously and it also helps to simplify the system structure by reducing possible moving parts in the traditional detecting system.In the spectral analysis,the position of spectrum line is a important paramter,for its direct relationship to correspondent wavelength.So the precision of spectrum line position on the detecting array will determine the precision of the correspondent wavelength.As signal obtained by using such array is sampling of original spectral signal,it may cause some deformation on the signal actually obtained compared with the original one.And the width of the detector element has convolution effect on original signal,which can cause increment in spectral half-width and displacement of the spectral line.The increment in half-width will decrease the spectrum resolution of spectrometer and the displacement will reduce the precision of the wavelength,especially for a micro spectrometer,which usually has a shorter spread span of working spectrum and a lower element resolution compared with traditional one.Under such circumstances,the spectrum displacement caused by light activated element can’t be ignored and a deep study of such influences should be carried out to find a possible way to overcome these problems.In this paper,the relationship between the displacement and the element width is analyzed and solution is put forward to correct the error between real spectrum line and reconstructed spectrum line.Authors study shows the displacement of the spectral line can be expressed by δb=-b,where b is the real spectrum line position and is the position actually measured,and authors find that b and satisfy a simple equation I(+Δ/2)=I(-Δ/2),where I(x) is the spectrum energy distribution in the space field and Δ is the width of the light activated element.The equation shows that there will no any difference between b and when the spectrum is of symmetry,and the difference will increase as the symmetry becomes worse.In fact,to obtain a fine precision do not required a good symmetry in the whole spectrum line.Only a fine symmetry in the rangeb-Δ/2,b+Δ/2]will lead to a high precision of spectrum line position.While in many circumstances to get a spectrum line of good symmetry in the whole range of working spectrum is very difficult and this would require a more complicated optical system,which will make it impossible to realize the miniaturization and integration of spectrometer.Further study shows that this problem can be easily settled by using deconvolution in frequency domain.