A handheld target marker is provided, wherein the target marker includes a housing retaining a quantum cascade laser, a collimating or focusing lens, a driver and a power supply. The quantum cascade laser produces a thermal infrared beam which can be selectively directed to impinge upon a target. The impinging beam is viewable by a thermal imager. The handheld target marker operates at ambient temperatures and incorporates the driver and power supply necessary for operation of the quantum cascade laser.