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: | PN. | Material | A(mm) | h (mm) | Deviation | Coating | | PTP0706 | N-BK7 | 7.0 | 6.0 | 30 arc sec | MAL + MgF2 | | PTP1010 | N-BK7 | 10.0 | 10.0 | 30 arc sec | MAL + MgF2 | | PTP2020 | N-BK7 | 20.0 | 20.0 | 30 arc sec | MAL + MgF2 | | PTP2525 | N-BK7 | 25.4 | 25.4 | 30 arc sec | MAL + MgF2 |
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