Multispectral imaging system for short wave infrared applications

A lot of applications as well as in the laboratory range and industrial range need a short-wave infrared imaging system. Especially multispectral imaging in that wavelength region are often enable new applications for quality assurance and monitoring of industrial processes. Due to the cost of the SWIR image sensors a multispectral imaging system should be flexible and adjustable to realize a maximum of applications. Normally push broom devices will fulfill these requirements. Disadvantages are that the sample must be moved, the spectral crosstalk and the blurring between the different channels can disturb the processing, and the correctness of spatial resolution along the scanning direction lead to uncertainties for dimensional measurements. For that reasons a twelve-channel filter-based imaging system was designed. A motor driven filter-wheel with a high precision drive will ensure that the filters will be placed in front of a SWIR Image sensor very precisely. To compensate the spectral aberrations along the optical axis a second drive positioning the image sensor into the focus plane. This enable sharp images in all spectral channels as well as high SNR (depends also on the capability of the SWIR Sensor). Furthermore, this implementation allows also to focus without changing the adjustment of the objective lens. A special designed dome light using halogen bulbs delivers very homogeneous radiation on the sample table. For the image readout, the control of the drives as well as the image presentation a software with a graphical user interface was developed. To export the image stacks in 3rd party software the imaging software saves the multispectral images in the envi-format.