Design of light receiver system for measurement of resonance Raman spectra in deep ultraviolet wavelength region

摘要

We are developing the remote measurement system for detecting harmful substances such as nitrogen dioxide and chemicalmaterials using the resonance Raman scattering effect. Although the most remote measurement systems were designed touse the light from ultraviolet to visible wavelengths region, the characteristic Raman spectra of complex materials wereobserved in deep-ultraviolet (DUV) wavelengths region. The development of the standoff detection system by measuringthe DUV light contributes to identify the various materials remotely. In this study, the design results of the Ramanscattering light receiving equipment (light receiving system) consisting of telescope, relay optical system and spectrometerwere considered. The optical design of the light receiving system was performed based on the estimation model of thesignal-to-noise ratio (SNR) and the ray tracing method. The important parameters (the attenuation of the laser pulse andRaman light in the atmosphere, the amplification factor of the scattering cross section in DUV wavelength region etc.) areincluded in the model, and SNR of the Raman spectrum can be evaluated by changing each parameter. The estimationresults suggest that SNR depends strongly on the reflectance of mirror and the amplification factor of the scattering crosssection in DUV wavelength region. The durability test of the mirror has been performed to evaluate the use in outdoor.The results show that the mirrors with high reflectance in DUV wavelength region have enough tolerance to thetemperature change and the scratch.