Hand-held optical triangulation position-determining instrument

Claim 1

A self-contained, hand-held, position-determining instrument for recording the position of the instrument in terms of the compass bearing to a first landmark, and the horizontal angle between the bearings to said first and a second landmark, comprising: a. frame means; b. a first directional index at a first end of said frame, and a second directional index at the second end of said frame to permit orientation of said instrument in the direction of said first landmark; c. first mirror means near said second directional index for imaging a second landmark in relation to said first landmark; d. second mirror means intermediate the ends of said frame, rotatable about a vertical axis, to image said second landmark on said first mirror, and means for indicating a function of the relative angles of said first and second mirror means; e. a compass with casing rotatably mounted to said frame, means to rotate said casing, index means on said casing, pointer means attached to said casing and means on said frame for indicating the angle of said pointer means; and f. means to display a portion of the compass graduations and compass casing index so as to be visible in the general direction of said first mirror, whereby the eye of the operator can simultaneously see the first landmark over the top of said first mirror, the second landmark in said first mirror, and said compass graduations and casing index.