Combined laser system and infra-red imaging system for e.g. surveillance aid - uses common optical system with paired zinc sulphide and zinc selenide lenses at objective and eyepiece

摘要

The optical system comprises an astronomical lens [11] and a field lens [12]. Mirrors [16,17] between the objective [10] and field lens fold the optic axis [14] of the telescope. The system uses a laser and refraction elements operative in the range of 0.5-14 micrometres. Infra-red radiation emitted from objects is received at the objective [10] and traverses to the infra-red imager [20]. Focussing of the laser along each path from source to return is maintained using a zinc sulphide lens [10,30,36] arranged in a pair, parallel to another constituent zinc selenide lens. The laser is brought to focus at the field element using hermetically sealed lens pair [60,61] spaced to withstand the power density of the laser beam.