Manually portable apparatus enabling high-resolution, two-dimensional infrared imaging of remote, non-contacting targets is described. An on-axis optical subsystem consists of a single, single-faceted planar scanning mirror that is reciprocable by stepper motors about two orthogonal axes. Oriented at approximately 45.degree. relative to the mirror's line-of-sight axis to a target, the scanning mirror reflects infrared energy incident thereon toward a spherical converging mirror, which may be manually focused to change the distance between it and a single-element, non-cryogenically cooled, heat-sensitive detector located behind the scanning mirror. An ADC, a microprocessor and a motor control circuit provide means for imaging the target by sampling the serial, conditioned output of the detector in timed relation to the angular positions of the stepper motors, and transforming energy density data to temperature data in a two-dimensional, pixel array. Integral display means are provided, by which a colorable infrared image may be viewed. In a proposed modification, a parabolic, rather than spherical, converging mirror is used. In another proposed modification, the detector interposes the scanning mirror and the converging mirror, insubstantially occluding the infrared energy reflected by the former.