Development of an Ultra-Sensitive Spectrometer

Abstract: A high dynamic range imaging (HDRI) spectroscopic instrument was designed and developed in this thesis. Achieving higher measurement accuracy in imaging spectroscopic measurements require both a suppression of the background light (stray light) as well as HDR imaging. A Digital Micromirror Device (DMD), which spatially modulates the light, was employed in the designed spectrometer to produce HDRI and the Periodic Shadowing technique was used for stray light elimination. A Czerny-Turner spectrometer was designed and developed, having a grid pattern at the entrance slit to enable Periodic Shadowing. The DMD was introduced at the output of the spectrometer, which allowed a desired percentage of the spectral lines to be reflected onto the detector. This made it possible to resolve weak spectral lines in the presence of intense ones at one exposure time, without saturating the camera. Experimental results are provided to demonstrate the capabilities of the device and the HDRI achieved. This instrument holds promise for improved Raman scattering spectroscopy, which currently is restricted by both stray light and a limited dynamic range.