Custom Risley prisms

Risley Prisms for Beam Steering, Made in Rye

Kingsview Optical makes custom Risley prism pairs for beam steering, scanning and pointing systems. We polish matched wedges to your deviation, design achromatic pairs where your system works across a waveband, and cement and coat them in our own cleanroom and chambers in Rye.

  • Made in Rye, East Sussex
  • Achromatic pairs cemented in-house
  • Coated in-house
  • ISO 9001:2015
Send Your Prism Drawing See the Specification
Round wedge prisms for Risley pairs made by Kingsview Optical in Rye, UK
Wedge prisms for Risley pairs, 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 Risley Prism Pair Does

In short: a Risley prism pair is two wedge prisms placed one behind the other. Rotating the wedges relative to each other, and together, steers the beam anywhere within a cone, from straight through to twice the deviation of one wedge.

Each wedge bends the beam by a small, fixed angle. When the two wedges line up, the deviations add. When they oppose, they cancel and the beam goes straight through. Every position in between points the beam somewhere inside the cone, so a Risley pair can steer a beam or point a camera with no mirrors and no moving optics in the beam path other than the rotating wedges.

A simple glass wedge bends blue light more than red, which spreads a broadband beam into colours. For imaging or multi-wavelength systems, each element can be an achromatic wedge: two glasses cemented together so their dispersion cancels. Optical glass choice is critical here, and our designers choose the glass pair for your waveband.

Because the two elements must deviate by the same amount, we polish Risley wedges as matched pairs and check them against each other. For single wedges and wedged windows on their own, see our optical wedges page.

Risley pair: two wedges deviate the beam.
Rotating the wedges steers the beam within a cone.
Applications

Where Our Risley Prisms Are Used

Beam steeringPointing a laser beam without mirrors or gimbals.
Scanning and LIDARScanning a beam in circular, spiral or rosette patterns.
Camera pointingLooking around a scene by rotating the prisms in front of a camera.
Laser alignmentFine adjustment of beam direction in optical set-ups.
Free-space optical communicationPointing and tracking for optical links.
Defence and securityCompact pointing optics for sights and sensors.
Specification

Risley 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
Wedge angleTo your required deviation, ±3 arcmin standard
ConstructionSingle wedges, or achromatic wedges of two cemented glasses
MatchingSupplied as matched pairs
AdhesivesNorland and NTT, others on request
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
FinishingBlackened edges, protective chamfers, steps, bevels, drilled holes

Not sure what to specify? Tell us the maximum steering angle you need, the clear aperture and the waveband. We'll work out the wedge angle and whether you need an achromatic design.

Options

Made to Fit Your System

CoatingsAR coatings designed for your waveband on every face
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 assemblyAchromatic elements cemented in our cleanroom, and pairs fitted into rotating mounts
Questions

Risley Prism Questions

How does a Risley prism pair steer a beam?
Each wedge deviates the beam by a fixed angle. Rotating the wedges relative to each other changes how much the deviations add or cancel, and rotating them together changes the direction. Between them, they can point the beam anywhere in a cone up to twice the deviation of one wedge.
What is an achromatic Risley prism?
One where each element is an achromatic wedge, two different glasses cemented together so their dispersion cancels. The beam is steered without being spread into colours, which matters for imaging and broadband sources.
How do I choose the wedge angle?
The deviation of a thin wedge is roughly (n − 1) times the wedge angle, where n is the refractive index. Halve your maximum steering angle to get the deviation each wedge needs, then choose the wedge angle for your glass. We'll do the calculation for you if you send the steering angle, aperture and waveband.
Do you supply Risley prisms as matched pairs?
Yes. The two elements need to deviate by the same amount, so we polish and check them as a matched pair.
Can you supply Risley prisms in mounts?
Yes. We can machine the mounts in our own workshop and assemble the prisms into them. The rotation mechanism and motors are usually designed by the customer.
What do you need to quote Risley prisms?
The maximum steering angle or wedge angle, clear aperture, waveband, whether you need achromatic correction, coatings and quantities.

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 Risley 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
  • Maximum steering angle, or wedge angle
  • Clear aperture and waveband
  • Whether you need achromatic correction
  • 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 Risley Prism Pair?

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.