High Precision Right Angle Optical Glass Prism

High-precision Right-Angle Prisms can be used to deviate a light path by 90° or 180°, depending on which surface is used as the input for the light source. These prisms are fabricated from N-BK7, UV fused silica, CaF2, or ZnSe, and they are offered in sizes ranging from 0.50 mm to 200 mm. Our N-BK7 right-angle prisms are available uncoated or with one of our three standard broadband antireflection coatings ( 350 – 700 nm,  650 – 1050 nm, 1050 – 1700 nm) on either the hypotenuse or both legs, thereby reducing surface losses.

Due to total internal reflection (TIR),  the right-angle prism can be used as a 90° reflector. When the input light is incident on one of the prism’s legs, it undergoes TIR at the glass/air boundary of the hypotenuse and exits via the other prism leg. This 90° deviation of the input light makes the right-angle prism a suitable alternative to a mirror.

The right-angle prism can also be used as a 180° retroreflector. When the input light is incident on the face of the hypotenuse, it undergoes TIR at the glass/air boundary at the prism legs. It undergoes TIR a second time at the next prism leg and exits the hypotenuse in a path parallel to that of the input beam. Like the retroreflector, the 180° deviation of the light path is independent of the angle at which the light enters the prism.

** UV Fused Silica Right-Angle Prisms, Uncoated (185 nm – 2.1 µm)

Choose a UV Fused Silica Right-Angle Prism if your application would benefit from higher transmission in the UV or a lower coefficient of thermal expansion. UV-grade fused silica offers high transmission in the deep UV and exhibits virtually no laser-induced fluorescence (as measured at 193 nm), making it an ideal choice for applications from the UV to the near IR. For a given wavelength, UV fused silica also has a lower index of refraction than N-BK7. Please see the Graphs tab for a graph of index of refraction vs wavelength for UV fused silica.

** N-BK7 Right-Angle Prisms, Uncoated (350 nm – 2 µm)

Choose an N-BK7 Right-Angle Prism if the additional benefits of fused silica are not required. N-BK7 provides excellent transmittance in the visible and near infrared portions of the spectrum. Please see the Graphs tab for a graph of index of refraction vs wavelength for N-BK7. Additionally, N-BK7 is a viable choice for UV applications down to 350 nm. For applications that demand maximum transmission, please see our AR-coated N-BK7 prisms below.

** CaF2 Right-Angle Prisms, Uncoated (180 nm – 8 µm)

Choose a CaF2 Right-Angle Prism for applications requiring high transmission in the 180 nm – 8 µm range. The material exhibits a low refractive index, varying from 1.35 to 1.51 within its usage range of 180 nm to 8.0 µm, as well as an extremely high laser damage threshold. Please see the Graphs tab for a graph of index of refraction vs wavelength for calcium fluoride. Calcium fluoride is also fairly chemically inert and offers superior hardness compared to its barium fluoride, magnesium fluoride, and lithium fluoride cousins.

** ZnSe Right-Angle Prisms, Uncoated (600 nm – 16 µm)

Zinc Selenide is ideal for use in the 600 nm – 16 µm range. It features low absorption (including in the red visible wavelength range) and high resistance to thermal shock. ZnSe is ideal for use in CO2 laser systems operating at 10.6 µm, including those with HeNe alignment lasers. Please see the Graphs tab for a graph of index of refraction vs wavelength for ZnSe.

When handling optics, one should always wear gloves. This is especially true when working with zinc selenide, as it is a hazardous material. Due to the low hardness of ZnSe, additional care should be taken to not damage these prisms.

++  N-BK7 Right-Angle Prisms, AR-Coated Hypotenuse

Choose an N-BK7 Right-Angle Prism with the appropriate AR Coating on the hypotenuse if you wish to use your prism as a retroreflector and you want to reduce surface reflections over the specified wavelength range of the coating

++  N-BK7 Right-Angle Prisms, AR-Coated Legs

Choose an N-BK7 Right-Angle Prism with the appropriate AR Coating on the legs if you wish to use your prism as a 90 degree reflector and you want to reduce surface reflections over the specified wavelength range of the coating.