Monolithic Miniature Spectral Sensor for Multi-Channel Spectral Analysis

The utilisation of spectral information gains increasing acceptance in many industrial processes. The reason for that is the very high resolution of the wavelength range. Thus, additional metrologically relevant data can be derived from image data. One problem of spectral signal processing is the mostly insufficiently low number of parallel analysable measuring signals. High quality multi-channel signal processing is only achieved by the parallel setup of multiple one-channel spectrometers. Therefore a new spectral sensor utilising a CCD matrix as image acquisition unit has been developed. The light is coupled into a monolithic optical system by optical fibres. Afterwards it is highly precise positioned on the monolithic optical system. In contrast to state of the art spectrometers single coupling directions are intentionally chosen as to not using the complete image. The aim of this approach is to sample single channels optically precise and to minimise the crosstalk of the single channels. The investigations and results regarding the crosstalk and the wave-length accuracy are outlined in detail. A significant result is that up to four channels from different measuring locations can be simultaneously analysed. Further investigations for the analysis of increasing the number of spectra and special applications are object of the ongoing research.