The spectral image acquisition and processing system based on folded gratings spectrograph and ICCD

Abstract

A spectral image acquisition and processing system based on a commercial available ICCD camera which has an internal Digital Delay Generator module and a purpose-built folded gratings spectrometer without movable parts internally was built up to fulfill the wide wavelength coverage, high spectral resolution and time-resolved detection requirement in oceanic environment. In this system, the spectral information is contained in the spectral images acquired by the camera. And some measures are taken to assure the image quality and acquisition efficiency: using DDG to resolve the image smearing; 4 readout speeds selectable to balance the readout noise and acquisition efficiency; arbitrary resolution spectral image (1024*1024 maximum) achieved by pixels binning or local image acquisition to improve image acquisition efficiency. In the course of image processing, wavelength calibration of every one of the 9 sub-images is done with Fourth-order Polynomial Calibration Methods. And then the 9 spectral segments are spliced into a complete spectral. The preliminary test results for LIBS of Cu plate show that the system can realize wavelength coverage of 300-700nm, 0.054nm spectral resolution and 0.1nm wavelength accuracy. The effectiveness of the image acquisition and processing methods make it a promising choice in the future combined spectrum detection system.