Performance comparison between a prism and diffraction grating in a low-cost spectrometer

Optical spectroscopy is a very important branch of chemistry; it can be used for the quantitative analysis of chemical specimen, but also provides a detailed view of the structure and behavior of chemical systems.When using fluorescence spectroscopy on weakly emitting samples, a very sensitive spectrometer must be used to collect as much of the signal as possible. For a spectrometer to operate correctly, it must be able to separate light into individual frequencies as accurately and efficiently as possible. The two common dispersive elements used in the visual Spectrum are a prism and a diffraction grating. A prism is a triangular shaped piece of glass which splits light into individual wavelengths by refraction. The diffraction grating being used for this experiment is a grating which has 1800 lines/mm. While diffracting gratings tend to perform better under normal conditions, the effects of ghosting and the presence of multiple orders of diffraction can cause a loss of signal for weakly emiting samples, even though only the first order is used.The experiments undertaken in this study use light sources at various intensities to assess the performance of a low-cost spectrometer with both types of dispersive elements. One set of experiments is performed using a diffraction grating (which is the dispersive element in the original spectrometer), while the diffraction grating is replaced by a modified prism for the second set of experiments