Autokollimátors
An autokollimator is an optical instrument used to measure small angles. It essentially consists of a telescope with a reticle in the focal plane of the objective lens. Light is collimated through the objective, forming a parallel beam. This beam is then reflected off a mirror or other surface. The reflected beam is refocused by the same objective lens, and the image of the reticle is observed through the eyepiece.
When the mirror is perfectly perpendicular to the collimated beam, the reflected image of the reticle is
Autokollimators are used in various applications where precise angle measurement is critical. These include alignment of