The document discusses the working principle, process, and applications of an angle dekkor, which is a type of autocollimator used to measure small variations in angular settings. It works by using a focal plane, collimating lens, and reflector to direct light from a point source back to the focal plane. The working process involves using a lamp, prism, microscope, eyepiece, and graticule to illuminate and view the angle being measured. Applications include measuring angles of components, checking V-block slopes, and measuring taper or cone angles.