Aluminized Optical Prisms Height 12.7mm Half Penta Prism Used In Telescopes

Overview:

Half-Penta prisms also known as Bauernfeind prisms or Semi-pentaprisms are used to deviate the line of sight by 45° without inverting or reverting the image. It is widely used in telescopes and also has applications in projection and imaging system, in microscope tubes, and in geodesy.

The Half-penta prism has the geometrical structure of a penta prism cut in half. The beam is reflected twice in the prism, first with total internal reflection and a second time on a coated reflecting surface. The prism requires aluminized and over-coated with Inconel and black paint for the non-TIR surface to be usable in practice.

Combining a Half-Penta Prism with a correspond size Schmidt roof prism creates a Pechan prism pair. The Pechan prism pair will invert or revert the image while not deviating the line of sight.

General Specifications of Half-penta Prism:

Material	BK7
Dimension Tolerance	±0.2mm
Angle Tolerance	<3 arc minutes
Roof Angle Tolerance	<3 arc sec
Flatness	λ/4@632.8nm
Surface Quality	60/40 scratch and dig
Clear Aperture	>90%
Coating	No coating, available

Standard Products of Half-penta Prism: