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Porro Prisms


Custom Porro prisms are variants of the standard 90° prism but used as a pair to displace and invert a beam. Custom Porro prisms are widely used in binoculars where they orientate the image correctly and reduce the total length of the binoculars by a small amount.

The Porro prism is shaped as a right-angled triangle and works by the light beam entering the long face (hypotenuse) at 90° and being reflected by TIR from the two sloped faces and exits the longest face at 90°.  As the light beam enters, and leaves, the prism at 90° the beam is not wavelength dispersed, that is, a non-dispersive prism.  Two of these prisms forming a double Porro with the longest faces angled at 90° to each other are used in, for example, binoculars to invert and revert the image so that it is orientated the correct way up and sideways.

Knight Optical supply high quality custom inverting Porro prisms made to your exact specification.  Every optical component is individually tested by our highly skilled technicians in our state of art metrology lab to ensure all components meet our high quality standards.  All prisms are tested on our Trioptics Prism Master capable of accuracy to 3 arc seconds.

Contact our multilingual technical sales team and discover how Knight Optical’s high quality custom Porro prisms and service can improve your instrumentation and supply chain experience.

Our 2018/2019 Catalogue

Inside Knight Optical’s catalogue you’ll find details of the industries we serve as well as the many other services we can offer. It also showcases hundreds of our most popular products, supported by useful technical information, to help you choose the right part for your application.
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