Range finders using projected images
Rebekah Stephens · Journal of research of the National Bureau of Standards · 1958
Two optical range find ers of six-inch base length have been designed and constructed for making measurements to arbitrary points on a model.One measures distances from 2.5 feet to 10 feet, thc other from 9.7 feet to 25 feet.The accuracy of all distances is plus or minus one-quarter inch or better.Because of unusual requirements of use these range find ers operate by projecting two images of a bright cross upon the target, which may be fused into a single image by adjustment of the range knob.