Feb 12 2014
The Schmidt prism, also referred to as Schmidt–Pechan prism, is a prism that reverts an image while deviating the line of sight by 45°. It is a type of optical roof prism.
Although the Schmidt–Pechan prism resembles the Pechan prism, there is a key difference between the two. The Schmidt prism has a roof edge while the Pechan prism does not. However, if a roof is added to the top surface of a Pechan prism by replacing its upper prism, a Schmidt prism can be formed. The Schmidt–Pechan prism has six reflections while the Pechan prism has five. Thus the Schmidt–Pechan prism has the ability to invert and revert images and thus can act as an image rotator.
The Schmidt–Pechan prism enables rotation of an image by 180°. It is primarily used in binoculars as an image erecting system. The ray deviation of 45° makes the Schmidt prisms very useful in eyepiece assemblies and imaging units that require a path bend.
It is recommended that this prism is bought as an assembled gadget, as the mounting of the parts is quite tricky and should be handled by experts.
References