Autocollimation
Under autocollimation is meant an optical structure in which a collimated light beam, an optical system leaves and is reflected by a polished end face again in the system.
One application is the autocollimator for precise measurement of small angles in the range of arc seconds (90 ° 0 ' 0 ")
With autocollimation it is also possible to determine the focal length of lenses or lens systems. In the case of a converging lens, an object (or a pinhole diaphragm) is initially positioned approximately at the focal point of the system and a plane mirror (at any distance) on the other side of the lens. Now the object is shifted until the image of the object, which is generated by the lens and mirror, is sharply in the same plane as the object (see drawing).
In the case of a thick lens or a lens system, the focal length can also be determined from the ratio of the bundle radius between the optics and the plane mirror to the tangent of half the opening angle. For this purpose, the divergent bundle has to be limited by a diaphragm so that its rays pass completely through the optics. The result can be used to determine the position of one of the two main levels .
Autocollimation is also suitable for measuring image defects that are not too large optics.
Web links
- Theresa Neuhierl: A new method for direction transmission by coupling inertial measurement technology and autocollimation. (Dissertation) Online (accessed August 23, 2012)
- Basics of autocollimators (accessed on April 19, 2014; PDF file) Missing 06/06/2020