It is no longer possible to use normal diffuse light to measure the diameter of rotationally symmetrical parts or the pitch on threads and taps, because the lights cannot "bend" around the edges, so that the diameter is indicated as less than it is in reality. Parallel bottom light can be used for such applications, because it guarantees that the light comes straight from below making precise measurement possible. The light from the blue LED (blue = least deflection) is guided though an optical systems by a semi-translucent mirror and passes through a Fresnel lens which radiates the light upward in parallel. The image quality corresponds to that of a high quality profile projector. The power pack included with the unit allows fine dimming in addition to standard dimming. If desired, this system is also available in a white or green version. Parallel illumination units have a fixed aperture.
Zeichnung - Drawing - PPL-B