US Patent 10955683 Imaging incident angle tracker

An imaging incident angle tracking device, including: a light source; a first and second beam splitters or dichroic mirrors; a position sensitive detector; wherein the first and second beam splitters or dichroic mirrors are configured to direct light from the light source to a window surface through an objective lens; the first and second beam splitters or dichroic mirrors is further configured to direct the light reflected from the window surface and through the objective lens into the position sensitive detector. A positioning system, including: a baseplate; a platform; a plurality of strut assemblies connecting the baseplate and the platform; wherein each of the strut assembly includes: a linear actuator; a first flexure assembly and a second flexure assembly at the first and second ends of the strut assembly; the first and second flexure assemblies are rigid along and flexibly bendable orthogonal to the length of the strut assembly.