Abstract: A method for focusing a rapidly moving scanning lens is disclosed. The lens is mounted onto a ferromagnetic insert which is attached to the scanning assembly. A stationary electromagnet generates a uniform magnetic field along the path of the scanning lens. This field is coupled to the ferromagnetic insert via a second ferromagnetic insert which is rigidly mounted to the scanning assembly. Changing the current in the electromagnet changes the position of the scanning lens and enables it to focus on the scanned object.

Abstract: The present invention relates to a device which replaces a video image of a light beam with a quantized image, having contours corresponding to preset intensity percentages. The continuous analog video waveform is replaced by a stepped waveform, resulting in contours to appear on the video image. These contours can be preset to appear at the common percentages of the maximum. The most useful contours are at 90%, 50%, 37% (corresponding to 1/e of intensity), 14% (corresponding to 1/e.sup.2 of intensity) and 10%. A normalizing circuit makes the contours independent of light level.