Optical design of concave grating Raman spectrometer

Portable Raman spectrometer is designed with concave grating and spherical mirror on basis of classic Czerny-Turner spectrometer in this paper. The equation of primary coma-free is concluded according to aberration theory of concave grating. Combined with geometrical relationship in tangential plane, the relation of size of image plane and parameter of this system is concluded. Laser of 532 nm is selected asexcitation light source with object numerical aperture (NA) of 0.12. Charge-coupled device (CCD) with 1024 pixel�64 pixel is selected as detector, in which 64 pixels is combined to make a linear array CCD. This design is simulated and analyzed by Zemax, and spectral resolution of 0.3 nm is realized at the band from 537 nm to 615 nm with a portable institutions. Image plane is analyzed in Zemax non-sequential mode. The whole band is in the receiving range of CCD, which proves the feasibility of this structure.