Development of a medium-size SWIR imaging telescope: integration, calibration, and MTF measurement

Development of an imaging telescope having a large mirror generally requires a sound infrastructure including expensive devices such as collimators and interferometers. In this paper we investigate the development and characterization of a medium size telescope (140 mm aperture) using simple techniques. Alignment was done with a mechanical measurement device. Detector was placed using an image of a ruled outside building. Radiometric calibration was done with open-sky images. And finally MTF was measured using stellar images. We found that MTF of our telescope is greater than %15 all along the detector at 20 lp/mm, which is the Nyquist frequency of 25 μm pixel size. This shows that alignment and focus adjustments work well enough in the telescope. These simple techniques can be used for the development and characterization of a medium-size and medium-resolution imaging telescopes.