Comparison of different methods to substantially improve the efficiency of filter-based spectroscopic sensors

Filter-based spectral detectors convince with their simple concept, an extremely compact and robust design and the possibility to adapt the addressed spectral range and the resolution to the individual application requirements. Unfortunately, these filter-based sensors usually suffer from low detection efficiency. In this contribution we discuss and compare different methods that allow to substantially increase the detection efficiency of filter-based spectral sensors. An initial concept is based on a wavelength-dependent redistribution of the incident light before it reaches the individual filter elements of the array. This approach allows a substantial increase in detection efficiency, but requires additional dichroic elements in the beam path. An alternative approach uses a folded beam path architecture and completely waives additional dichroic elements. This approach is not only suitable for filter-based spectral sensors, but can also be transferred to increase the efficiency of hyperspectral imaging systems.