High performance cooled LWIR imager optics for optronics mast systems

The development and performance verification of a cooled long wave infrared (LWIR) imager optics for a high resolution 10μμm pitch detector is described for the next generation optronics mast systems (OMS). The optical system features a Field of View (FOV) changing re-imager architecture, offering high definition imagery over a 3x magnification range under harsh environmental and built-in conditions, characteristic of submarine periscope applications. Details concerning optical design philosophy and evolution of the system from low (320x256) to high resolution (1024x768) detectors are discussed. The optical system includes a steerable de-scanner plate that enables motion blur compensation in a fast azimuth scan mode of the system for panoramic image acquisition. A conceptual framework simulates the complete imaging path taking into account a combination of relative illumination, distortion and relative boresight error across the FOV's of the system. Systematic limitations of the achievable optical performance due to metrology assisted alignment processes are analyzed with ray-trace modelling. Optical performance metrics of as-built systems from the OMS family are studied from a predictive modelling perspective to qualitatively understand their dominant error modalities. These are used to recommend actions to maximize achievable as-built optical performance for the system under development.