Abstract: An optical coordinate transfer assembly provides angular correlation between spatially separated objects. In a particular embodiment of the invention, roll, pitch and yaw of a second directional device 12 relative to a first directional device 11 can be measured (and correction and/or compensation therefor can be made) using an optical alignment sensor 20 mounted on the first directional device 11 and a rooftop-mirror/lens assembly 21 mounted on the second directional device 12. Light beams projected from the optical alignment sensor 20 are reflected by reflector devices 35 and 36 on the rooftop-mirror/lens assembly 21 to linear arrays 69, 70 and 78 of photodetectors, which generate electronic signals indicating angular discrepancies between the orientations of the first and second directional devices 11 and 12 in three degrees of freedom to sub-microradian accuracy over a wide range of measurements.

Abstract: The improved Absolute Distance Sensor has achieved presently a resolution of about 0.03 .mu.m (RMS) for measurements over long distances. A two-color, synthetic Michelson interferometer employing a CO.sub.2 source is designed to sequentially switch between four sets of R and P line pairs and thereby provide a basis for forming simultaneous equations which are employed to greatly reduce the half wavelength ambiguity typical of single wavelength interferometers.

Abstract: A CO.sub.2 laser operating in the 10 .mu.m band is stabilized by a stabilization circuit that compares the power in a selected pair of R and P lines. A switching circuit connected into the stabilization circuit causes the laser's operating point to be switched within a short interval wherein four different pairs of R/P lines can be output within about 100 ms.