90 Degrees Deviation Penta Prism

Penta Prism, 90 Degrees Deviation Prism, Right-Handed Image Prism

Overview:

A Penta Prism is a five-sided reflecting prism used to deviate a beam of light by a constant 90°, even if the entry beam is not at 90° to the prism. The beam reflects inside the prism twice, allowing the transmission of an image through a right angle without inverting it (that is, without changing the image's handedness) as an ordinary right-angle prism or mirror would.

The reflections inside the prism are not caused by total internal reflection, since the beams are incident at an angle less than the critical angle (the minimum angle for total internal reflection). Instead, the two faces are coated to provide mirror surfaces. The two opposite transmitting faces are often coated with an antireflection coating to reduce spurious reflections. The fifth face of the prism is not used optically but truncates what would otherwise be an awkward angle joining the two mirrored faces.

Penta prism is the ideal optical tool for defining a right angle in an optical system, laser level and alignment.

General Specifications of Penta Prism:

Material	BK7, UV grade Fused Silica
Dimension Tolerance	±0.2mm
90° Deviation Tolerance	30 arc seconds
Flatness	λ/4@632.8nm
Surface Quality	60/40 scratch and dig
Clear Aperture	>90%
Chamfer	Protective<0.5mm@45°
Coating	Protected Aluminum reflective coating Single Layer MgF2 AR coating at VIS

Standard Products of Penta Prism: