Custom right angle prisms

Right Angle Prisms, Made to Your Drawing in Rye

Kingsview Optical makes custom right angle prisms for OEMs, instrument makers and research labs, from 0.8mm micro prisms for endoscopes to large prisms for periscopes and test equipment. We shape, polish, coat and measure every prism at our site in Rye, East Sussex, from a single prototype to production batches.

  • Made in Rye, East Sussex
  • Micro prisms from 0.8mm
  • Coated in-house
  • ISO 9001:2015
Send Your Prism Drawing See the Specification
Custom micro prisms made by Kingsview Optical, right angle prism manufacturer UK
Micro prisms beside a £1 coin, made in Rye.
Prisms made here, start to finish. Shaped, polished, coated, cemented and measured at our site in Rye.
See how we make them →
The basics

What a Right Angle Prism Does

In short: a right angle prism is a 45°-90°-45° prism. Light entering one short face reflects off the hypotenuse by total internal reflection and leaves the other short face, turned through 90°. Used the other way round, through the hypotenuse, it sends light back through 180°.

Because the reflection is total internal reflection, a right angle prism folds a beam with no mirror coating and almost no loss, which makes it a robust, low-cost replacement for a fold mirror. It is the most widely used prism in optical instruments.

A single reflection gives a mirror image, flipped in one axis. Where the image must stay correct-handed, a penta prism or an Amici roof prism is usually the better choice. Used through the hypotenuse, two right angle prisms make a Porro system for erecting an image.

If the beam meets the hypotenuse at too steep an angle for total internal reflection, for example with a wide field of view, we mirror-coat the hypotenuse with protected aluminium, silver or a dielectric design. Two right angle prisms cemented with a polarizing coating on the hypotenuse make a polarizing beamsplitter cube.

Right angle prism: the beam reflects off the hypotenuse and turns through 90°.
ObjectFRight angle prismImageF
A single reflection mirrors the image in one axis.
Applications

Where Our Right Angle Prisms Are Used

Endoscopes and medical imagingMicro prisms that turn the view through 90° at the tip of an instrument.
Periscopes and sightsFolding the optical path in defence and security instruments.
Machine visionFolding long optical paths into compact camera and inspection housings.
Laser systemsSteering and folding beams with low loss, without a mirror coating.
RetroreflectionUsed through the hypotenuse to return a beam through 180°.
Scientific instrumentsBeam folding in spectrometers, microscopes and test rigs.
Specification

Right Angle Prism Specification

These are our standard tolerances. If your design needs tighter, tell us which parameter. We'll tell you plainly whether we can hold it, and what it adds to cost.

Size range0.8mm micro prisms to over 100mm
Dimension tolerance±0.1mm
Angle tolerance±3 arcmin standard, tighter on request
Angles45°-90°-45°, or other angles to your design
Reflecting faceTotal internal reflection, or mirror-coated hypotenuse
Flatnessλ/4 @ 633nm
Surface quality (scratch-dig)60/40 standard, 40/20 on request
MaterialsSchott, Ohara and CDGM optical glass; fused silica
CoatingsBroadband AR (standard 425 to 650nm, wider on request), wide-angle AR, V-coat, MgF2, custom designs; metal or dielectric mirror on the hypotenuse
FinishingBlackened edges, protective chamfers, steps, bevels, drilled holes

Not sure what to specify? Angle tolerances tighter than your system needs are the most common hidden cost in a prism quote. Tell us how the prism is used and we'll help you check.

Options

Made to Fit Your System

CoatingsAR on the short faces, and a metal or dielectric mirror on the hypotenuse if needed
Edge featuresProtective chamfers, steps, bevels and blackened faces, CNC shaped to suit your mount
Mounts and housingsPrism mounts and housings from our own machine shop Cementing and assemblyPrisms cemented into pairs, or fitted into mounts and assemblies
Questions

Right Angle Prism Questions

Does a right angle prism need a mirror coating?
Usually not. When light enters a short face square-on, it meets the hypotenuse at 45°, beyond the critical angle of common optical glass, so it reflects by total internal reflection. A mirror coating is needed if the beam arrives at steeper angles, for example with a wide field of view, or if the hypotenuse will be in contact with adhesive or a mount.
What is the smallest right angle prism you can make?
Our micro prisms start at 0.8mm. Small prisms like these are used at the tips of endoscopes and in compact sensors. Send the drawing and we'll confirm the tolerances we can hold at that size.
Right angle prism or fold mirror: which should I use?
A right angle prism needs no reflective coating, can't tarnish, and is stiff and stable in a mount. A mirror is lighter and has no glass path, so it adds no chromatic effects in converging light. For compact, rugged instruments a prism is usually the better choice.
Does a right angle prism invert the image?
It mirrors the image in one axis, because there is one reflection. Used through the hypotenuse with two reflections, it inverts the image in one axis and returns it through 180°. If you need a correct-handed image after a 90° turn, use a penta prism or an Amici roof prism.
Can you make right angle prisms with mounting features?
Yes. We can add steps, bevels, protective chamfers, drilled holes and blackened faces, and supply prisms fitted into mounts machined in our own workshop.
What do you need to quote a right angle prism?
A drawing showing the leg lengths, height, angles and which faces are polished, plus the glass type, coatings, tolerances and quantities for prototype and production.

Other Prisms We Manufacture

Right angle Penta Roof Dove Risley Optical wedges PSPolarizing cubes

Or see our full optical prism manufacturing capability, and our optical design service if you need help choosing or designing a prism.

Getting a Quote for Right Angle Prisms

Send us your prism drawing. An engineer from the team that would make your prisms, not a sales team, will review it. They'll tell you plainly what's achievable and what will drive cost.

What to send

  • Drawing (PDF or ISO 10110) with dimensions and angles
  • Glass type, or the wavelength range if you're not sure
  • Angle and surface tolerances
  • Coating for each face: AR, or a mirror on the hypotenuse
  • Quantities: prototypes and expected production volumes

What happens next

  1. An engineer reviews itWithin one working day, flagging anything that will drive cost or lead time.
  2. We quote the prismFor the prototype, and for production at your volumes.
  3. We make, measure and deliverAll in Rye, with inspection data if you need it.
Start Your RFQ

Need a Custom Right Angle Prism?

Send your drawing, or describe what the prism needs to do. We'll tell you plainly how we'd make it, what it will cost and how long it will take.

Send Your Prism Drawing Call 01797 226202
Made in Rye, East Sussex. NDA-friendly. Defence and security work welcome. ISO 9001:2015.