Knight Optical supply deviating penta prisms that cover the visual and NIR range.

The deviation prism is an optical component that will redirect a light beam into another known angle relative to the incoming beam. The penta prism is a deviation prism which are used in cameras with a movable mirror that bends the beam vertical onto the focus graticule. The penta-prism provides a 90° deviation of the beam from the focus plane and, via an eyepiece, the user can aim the camera along the same axis as the beam that is focussed onto the detector, electronic or wet film. Deviations through other angles can be accomplished using, for example, abbe constant deviation, littrow, and wadsworth prisms.  

The penta prism has two surfaces that reflect light. The deviation of the light in a penta prism is set by the angle between the two surfaces which is constant. This leads to a situation where the light is deviated by a constant angle which is independent of the incidence angle of the light falling on the prism. This can allow simplification of a design as the need for adjustments can be considerably reduced. Our range of stock penta prisms have aluminised reflecting surfaces and very tight deviation tolerance.  Penta prisms are excellent in metrological applications, e.g. for setting up axes accurately for right angles. Typical usages for penta prisms are for beam steering and range finding, surveying and alignment in an optical system.