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  • Solid Penta Prism

    Penta Prism
  • Roof Penta Prism

    Penta Prism
  • Roof Penta Prism Beam Deviation Inspected on Interferometer

    Penta Prism
  • Master Hollow Penta Prism < 1 Arc Second Accuracy

    Penta Prism

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Penta Prism / Half Penta Prism

Typical Specifications

  • Material: N-BK7, Fused Silica, Custom
  • Sizes: 3mm to 200mm
  • Dimensional Tolerances: ± 0.012mm to ± 0.250mm
  • Clear Aperture Types: circular, square, custom
  • Clear Aperture Sizes: up to 90% of edge dimension / surface area (typical)
  • Surface Quality: Per MIL-PRF-13830_B; ANSI/OEOSC OP1.002-2009; ISO 10110
  • Roof-Edge Chips: < 0.010mm to < 0.127mm
  • Bevels: 0.25mm – 0.50mm face width or custom
  • Surface Flatness: λ/40 – λ/8
  • Transmitted Wavefront: λ/20 – λ/4
  • Beam Deviation: < 1 arc second to < 5 arc minutes
  • Coatings: Laser line anti-reflection, broadband anti-reflection, dielectric mirrors, metal mirrors, custom coatings

The penta prism employs reflection off two surfaces to deviate a light beam by 90° while preserving image parity. The beam deviation is invariant to slight rotation of the prism, making it useful for applications where critical alignment is necessary. Alternate prism configurations include the roof penta, which reverses the parity of the image, and the half-penta, which deviates light by 45°. Penta prisms are commonly used in image erecting assemblies and as laser insertion prisms for advanced surveillance and range-finding applications.

Aluminum, silver, and gold mirror coatings with protective epoxy paint overcoats are commonly applied to the two reflecting faces of the penta prism. Alternatively, the 22.5° incident angle upon the reflecting faces is ideal for dielectric high reflective mirrors and dichroic beamsplitter coatings that operate over wide cone angles.

Precision Optical is pleased to offer a diverse selection of standard and custom penta prism configurations with excellent beam alignment, image clarity and cosmetic quality. Laser-line and broadband anti-reflection coatings are available on the entry/exit faces, and protected metal as well as custom dielectric coatings are available on the reflecting faces. Penta prisms may also be bonded to wedges prisms or other components to create optical subassemblies. Please visit our coating and assembly capabilities pages for more information.

Precision Optical has the ability to precisely measure the accuracy of 90 degree azimuthal beam deviation with our state-of-the-art metrology equipment and custom tooling. Our high-end goniometers allow for advanced, modern inspection techniques. Our laser interferometers combined with precise custom optical and mechanical fixturing, allow highest resolution penta prism measurements, with precision near 0.5 arc seconds. This capability makes Precision Optical a leader in the production of high-end penta prisms.