Pyrometer 1

An instrument adapted to be disposed remotely from a target and comprising:

• manually operated optical range finding means for measuring the distance between target and instrument, said finding means including an objective lens mounted in a rotation-type focusing mechanism, split image effect prisms and a viewing screen whereby a split image appears on the screen plane when viewing until the mechanism is rotated to a unique angular position at which the image split disappears, said unique position being a monotonic function of said distance;
• a multi-turn potentiometer having first and second fixed contacts at opposite ends thereof and movable contact therebetween;
• and
• mechanical gearing means responsive to mechanism rotation and connected to said potentiometer to move said movable contact along said potentiometer in accordance with mechanism rotation to establish for each unique focusing position of said lens a corresponding unique position of the movable contact with respect to said first and second fixed contacts.