Characterization of fiber-based slit homogenizer devices in the NIR and SWIR

In this contribution, an approach for the characterization of various fiber-based slit homogenizer devices in the NIR and SWIR is shown. The devices are to be tested for use in a satellite-based spectrometer for spatial monitoring of anthropogenic greenhouse gases. This leads to the characterization requirement for temporal coherence and spatial incoherence. Speckle noise has to be reduced to a very low level, which is achieved using a fixed diffusor in combination with a rotating diffusor and a tunable (wavelength) laser as well as temporal averaging. Remaining variations due to unwanted interferences at the imager are removed by controlled movement of the sensor with an automated micro positioning stage in combination with image processing. The design, realization and characterization of the measurement breadboard as well as near field homogenization results for different input scenes and polarizations are shown. Additionally, the geometric characteristics and the depolarization effect of the fibers are investigated for a homogeneous input scene. Furthermore, a setup and measurement results concerning the focal ratio degradation of the fibers are presented.