A multi-spectral optical system comprising: reimaging foreoptics positioned to receive incident electromagnetic radiation and reimage the electromagnetic radiation onto an intermediate image plane; an alignment assembly for facilitating alignment of a first imaging sensor and a second imaging sensor including: a pair of plates selectively positioned at the intermediate image plane, the pair of plates including a first plate and a second plate spaced apart to define a gap between the first plate and the second plate, the first plate having a plurality of apertures formed in a reflective surface thereof, an illumination source positioned to direct illumination at the reflective surface of the first plate, wherein the first plate is interposed between the second plate and the illumination source, and a heating element coupled to the second plate and configured to heat the second plate to emit thermal infrared radiation from the second plate; a controller; an actuator mechanically coupled to the pair of plates and configured to move, in accordance with control signals provided by the controller, the pair of plates between an engaged position substantially at the intermediate image plane, and a disengaged position removed from the intermediate image plane; a first imaging sensor configured to receive reflections of the illumination from the reflective surface of the first plate when the pair of plates is in the engaged position; and a second imaging sensor configured to detect an image contrast created by a thermal emissivity difference between the first plate and the second plate, as viewed by the second imaging sensor through the apertures in the first plate, when the pair of plates is in the engaged position. reimaging foreoptics positioned to receive incident electromagnetic radiation and reimage the electromagnetic radiation onto an intermediate image plane; an alignment assembly for facilitating alignment of a first imaging sensor and a second imaging sensor including: a pair of plates selectively positioned at the intermediate image plane, the pair of plates including a first plate and a second plate spaced apart to define a gap between the first plate and the second plate, the first plate having a plurality of apertures formed in a reflective surface thereof, an illumination source positioned to direct illumination at the reflective surface of the first plate, wherein the first plate is interposed between the second plate and the illumination source, and a heating element coupled to the second plate and configured to heat the second plate to emit thermal infrared radiation from the second plate; a pair of plates selectively positioned at the intermediate image plane, the pair of plates including a first plate and a second plate spaced apart to define a gap between the first plate and the second plate, the first plate having a plurality of apertures formed in a reflective surface thereof, an illumination source positioned to direct illumination at the reflective surface of the first plate, wherein the first plate is interposed between the second plate and the illumination source, and a heating element coupled to the second plate and configured to heat the second plate to emit thermal infrared radiation from the second plate; a controller; an actuator mechanically coupled to the pair of plates and configured to move, in accordance with control signals provided by the controller, the pair of plates between an engaged position substantially at the intermediate image plane, and a disengaged position removed from the intermediate image plane; a first imaging sensor configured to receive reflections of the illumination from the reflective surface of the first plate when the pair of plates is in the engaged position; and a second imaging sensor configured to detect an image contrast created by a thermal emissivity difference between the first plate and the second plate, as viewed by the second imaging sensor through the apertures in the first plate, when the pair of plates is in the engaged position.