基于谱图还原的中阶梯光栅光谱仪有效波长提取算法

An Effective Wavelength Detection Method Based on Echelle Spectra Reduction

中阶梯光栅光谱仪具有高色散、高分辨率、宽波段、全谱瞬态直读等诸多优点,是先进光谱仪器的代表之一。在中阶梯光栅光谱仪民用化、商品化的发展趋势之下,其二维谱图图像处理的地位越来越重要。目前,国内一般先利用质心提取算法计算光斑质心再结合谱图还原算法计算有效波长,但这种方法难以达到较为理想的要求。为了提升运算速度、波长提取精度以及成像误差补偿能力,提出了基于谱图还原的有效波长提取算法。利用谱图还原算法,将探测器拍摄的二维谱图转换为一维图,通过改进的直方图双峰法选取阈值对一维图降噪,实现了二维谱图中全部有效(x,y)点对应波长的一次性提取。先将二维谱图转换为一维图进行图像处理,使算法在提升运算速度的基础上提取精度也得到了改善,还可以对一定范围内的成像误差进行补偿。采用标准汞灯作为待测光源开展了中阶梯光栅光谱仪成像实验,并使用该算法进行数据处理。实验结果表明,不仅能够自动补偿光谱仪0.05μm(两个像元)以内的成像偏差,而且能在精确提取有效波长的基础上大幅提升运算速度,波长误差小于0.02 nm,满足中阶梯光栅光谱仪图像处理的要求。

Echelle spectrometer with high dispersion,high resolution,wide spectral coverage,full spectrum transient direct-reading and many other advantages,is one of the representative of the advanced spectrometer.In the commercialization trend of echelle spectrometer,the method of two-dimension spectra image processing is becoming more and more important.Currently, centroid extraction algorithm often be used first to detect the centroid position of effective facula and then combined with echelle spectrum reduction method to detect the effective wavelength,but this method is more difficult to achieve the desired require-ments.To improve the speed,accuracy and the ability of imaging error correction during detecting the effective wavelength,an effective wavelength detection method based on spectra reduction is coming up.At the beginning,the two-dimension spectra will be converted to a one-dimension image using echelle spectra reduction method instead of finding centroid of effective facula.And then by setting appropriate threshold the one-dimension image is easy to be dealing with than the two-dimension spectra image and all of the pixel points stand for effective wavelength can be detected at one time.Based on this new idea,the speed and accu-racy of image processing have been improved,at the same time a range of imaging errors can be compensated.Using the echelle spectrograph make a test applying this algorithm for data processing to check whether this method is fit for the spectra image processing or not.Choosing a standard mercury lamp as a light source during the test because the standard mercury lamp have a number of known characteristic lines which can be used to examine the accuracy of wavelength detection.According to experi-mental result,this method not only increase operation speed but improve accuracy of wavelength detection,also the imaging er-ror lower than 0.05 mm （two pixel）can be corrected,and the wavelength accuracy would up to 0.02 nm which can satisfy the requirements of echelle spectrograph for image processing.