A digital range sensor comprises a light source, an optical element to focus the light from the source down to a small spot on a target, a second optical element that is mounted obliquely from the source axis, and a prism mounted on a multi-element detector, which in turn is mounted at the focus of the...http://www.google.com/patents/US6288786?utm_source=gb-gplus-sharePatent US6288786 - Digital range sensor system
