Spectrometer Design approaching the Limit

摘要

The design limits of grating array spectral sensors are discussed. The limit of a grating spectrometer with respectto the resolution is given by the diffraction limit of the grating. To approach the limit for the visible spectralregion the entrance slits should reach a width of 2 μm and larger depending on wavelength and numericalaperture. The detector pixel sizes should be in the same range, which is achieved virtually by the discussed doublearray arrangement with a transmissive, static slit array and detector array.A number of techniques are applied for optimizing the performance as well as for miniaturization. A sub-pixelimaging including a sub-pixel analysis based on the double array arrangement virtually reduces the detector pixelsizes down to about 20%. To avoid the imaging aberrations the spectra is imaged from different entrancepositions by the entrance slit array.The throughput can be increased by using a two dimensional entrance slit array, which includes a multiplexpattern or a fixed adaptive pattern.The design example of a UV-Raman spectral sensor is presented including spectral measurements.