Research On A High Resolution Spectrometer Based On CCD

CCD(Charge-coupled Device)direct-reading portable spectrum analyzer has a wide range of applications in areas such as environment monitoring and food safety.The existing spectrometer based on linear array CCD is short of low resolution,and that based on area array CCD is too costly.This thesis presents a novel structure of direct-reading spectrum analyzer based on linear array CCD.The main work is as follow:A novel structure of linear array CCD direct-reading spectrum analyzer is presented based on waveband-splitting of the spectrum and space-division multiplexing of the grating,which helps to improve the wavelength resolution substantially.A rotating plate with two different optical filters is placed in front of the CCD detector.The spectrum is split into two sub-wavebands and the sub-wavebands are detected by the CCD in sequence,thus waveband-splitting of the spectrum is implemented.An array of optical filters is placed in front of the grating.Each filter is aligned in a certain position and angle.Thus the central wavelengths of different sub-wavebands incident on the grating in different angles,while the diffraction angles keep coincidence.Thus space-division multiplexing of the grating is implemented.Based on M-type Czerny-Turner optical structure and employing the technologies such as waveband-splitting of the spectrum and space-division multiplexing of the grating,a CCD direct-reading spectrum analyzer is designed.The spectrum measuring range is 450-850 nm,which is split into two sub-wavebands 450-650 nm and 650-850 nm centering on650 nm.Considering correction of spherical aberration,comatic aberration,astigmatism,wide band and wide field optical aberration,the parameters of the optical system and components are designed,including the slit,collimating mirror,grating,focusing mirror and CCD detector.The optical system is modeled and simulated with ZEMAX software.An experimental platform is constructed to verify the feasibility of the spectrum analyzer.A 650 nm red lasersource is employed for optical alignment and a low pressure mercury argon lamp is employed for wavelength calibration.The a 532 nm green laser and 650 nm red laser are measured with the assembled spectrum analyzer.The wavelength error is 0.879 nm and1.26 nm for the two lasers respectively.The experimental results verified the feasibility of the proposal,while further research and optimization is required.