Abstract: A contour plotter for testing the response of an infrared detector comprig a small, cathode-ray tube with a hidden electron gun for generating a flying-hot-spot raster, a refracting, optical lens for focussing a reduced image of this raster on the detector under test, an oscilloscope, a two-dimensional sweep generator for sweeping the oscilloscope and the small, cathode ray tube in synchronism, and an electronic amplifier for applying the output of the detector to the Z-axis of the oscilloscope so that the intensity of the oscilloscope scanning beam is varied in accordance with the detector output response.In one embodiment, the small, cathode-ray tube uses an infrared phosphor screen to produce a small source of radiation. In a second embodiment, the cathode-ray tube uses a thin membrane screen formed by a thin film dielectric substrate with a refractory metal film deposited on it for producing a flying hot spot.