Abstract: This is a target projector projecting a vertical line source of infrared energy for testing of thermal imaging sensors. A vertical wire of a material which heats and emits infrared energy when an electrical current is passed therethrough is heated by a DC source. There is a projector for intercepting a portion of infrared energy from the wire, for passing only a line source beam portion which comprises a narrow beam of about 10 milliradians width and subtends a vertical angle of about 40.degree., and for directing the narrow beam on an optical center line of a thermal imaging sensor being tested. One type of projector comprises a narrow vertical mirror oriented about a longitudinal axis of rotation which is in a common plane with the wire disposed between 4" and 10" from the wire and rotatable about the axis of rotation to project the line source beam in a desired direction. In another projector, the mirror is replaced by a slit. The wire and projector in combination are also rotatable to a position 45.