Studies On Lens Imaging Spectrograph With Large Aperture

Raman spectrum is widely used as a material testing methods since discovered, Raman scattering effect exist in all molecule, whatever gaseous, liquid or solid. The application of Raman spectrum in gases is quite limited due to its low intensity. A kind of lens imaging spectrometer is designed for Raman scattering of gases in this paper, the strongest feature for this spectrometer is the use of camera lens with high NA as the collimating and converging optics and transmission volume phase holographic grating with high diffraction efficiency as spectroscopic devices, and the sensitivity of the instrument is the top factor to be considered in the design.We determined the performance index of the spectrometer according to the requirement,then Calculate the initial structure of spectrometer. After we manufacture the spectrometer we give a detailed test to it, and build test installation for gas Raman spectrum, the results show that the parameters of the spectrometer is all within the limits of expection and the spectrometer can obtain Raman spectral lines clearly and definitely in a relatively short time. In the test, we also find some shortcomings, spectrometer with high NA introduces a strong slit curve due to light oblique incidence grating and the beam splitting system is not accord to the CCD camera system. To improve the spectrometer, firstly we analysized the cause of the slit curve and correct the slit curve based on the slit curve formula, Then designed the converging lens according to the actual situation of the instrument, which can match the CCD spectral system, to improve the performance of the system.