Amici prism
The Amici prism (named after its inventor Giovanni Battista Amici ) is an optical prism belonging to the erecting prism . It is used in optical systems to bend a beam path by 45 ° or 90 ° without causing any interchanging of two opposite sides or making the image not mirror-inverted.
It is also called the Amici roof prism because its reflective surfaces only have two roof edges. In its abbreviated name, roof prism , it represents the basic form of all more complex inverted prisms that also contain roof prisms.
Structure and functionality
The Amici prism is a normal prism in the shape of a half-cube (right-angled triangle as base) with a "roof edge" placed on the long side ( hypotenuse side ), i.e. with two attached partial surfaces at right angles to each other.
In the roof prism part, the image is split in the middle, and the fields are reflected twice separately before they reunite. This must be done with a high degree of accuracy - accurate to about 3 to 4 arc seconds - otherwise double images will result. The necessary precision generally makes the production of the Amici prism more expensive. With the automatic production used today, however, the difference is hardly there.
Roof pages are also used in many other prisms for image change, to include the roof prism and penta , the Schmidt-Pechan , the Abbe King and Uppendahl prism .
Application and similar prisms
The Amici prism is used, for example, in the finder of a telescope and is therefore frequently used in observational astronomy, among other things . The advantage here is that the upright and laterally correct position of the objects in the telescope makes orientation easier, since the direction of movement of the instrument and the observed displacement in the eyepiece are the same.
Prisms that are used for similar purposes are the roof-prism pentaprism , which is particularly common in cameras, and the double Porro prism , which is often built into binoculars.
Finderscope with Amici prism
Amici prism with 45 ° deflection and 1.25 ″ plug size
