An infrared imaging sensor compatible with 2nd Generation Forward Looking Infrared (FLIR) Horizontal Technology Integration (HTI) B-Kit based sensors. In one example, the infrared imaging sensor includes a set of refractive opto-mechanical modules, including an afocal optical module, a receiver assembly, and backward- and forward-compatible electronics modules. The afocal optical module is configured to provide a plurality of different fields of view for the infrared imaging sensor. In one example, the sensor is configured for MWIR and LWIR imagery.