Abstract: A beam from a test image is split into two paths. The beam in one path may pass through broad-band or narrow-band attenuators to the intensifier being tested. A portion of the beam in the other path passes through a hole in a reflector to the eye of a viewer. The intensifier provides an output beam, and this beam is reflected by the reflector to the eye of the view. The viewer thus sees an image that may have a lighter or darker portion, depending on whether the output beam from the intensifier is brighter or dimmer than the test image. Various attenuators may be inserted in the one optical path to provide tests of such things as intensifier gain, relative gain, or EBI on a go/no go basis.