(under subclass 4.01) Subject matter that includes a way to mechanically, or otherwise, sample the "image" along the optical axis of a fixed focus lens or scan the focus of a transmitted beam to determine the point of maximum focus of the image or reflection of the source which is proportional to the distance to the targeted remote point.
SEE OR SEARCH THIS CLASS, SUBCLASS:
4.04, for determining range based on the focus characteristics of an image at some fixed point from the focusing lens.
