Where the other prisms in the group fold beams through large angles, the wedge prism is the fine adjustment: two faces inclined at a slight wedge angle deviate the beam by a small, precise amount set by the wedge angle and the glass index. One wedge gives a fixed deviation; two wedges rotated against each other — a Risley pair — steer the beam anywhere inside a cone, which is how compact instruments scan and centre beams without moving the detector or the source.
For any wedge requirement, precision is the operative specification issue: the deviation is only as repeatable as the wedge angle itself, so angle tolerance and face flatness must be confirmed for the exact part. The catalogue record used for this site lists prism families such as right angle, penta, cube, roof, Porro, Dove and rhombic, but it does not record a wedge prism product entry. Wedge prisms also serve as anamorphic and correction elements in instrument optics, and in pairs as compensators that trim out small alignment errors designed into an assembly on purpose — the error is budgeted, then wedged out.
Specifying a Wedge Prism
| Specification item | Why it matters |
|---|---|
| Wedge angle or required deviation | The two are linked by the glass index; state either and the quotation works from it |
| Diameter / clear aperture | Sets the beam size the wedge can steer without clipping |
| Glass | Index decides deviation per degree of wedge; state the required glass or the deviation at the design wavelength |
| Coating | State the coating requirement in the enquiry; the coating for the part is confirmed in the quotation |
For the large-angle end of beam folding, see right angle prisms; for the whole prism family in context, the prisms overview. No wedge prism minimum, price or stock specification is published here; the written reply must first confirm whether the part can be supplied.
Frequently Asked Questions
What deviation can a wedge prism give?
Small angles — the exact value follows from the wedge angle and glass index. State the deviation you need; no wedge listing is recorded in this catalogue, so availability and the wedge angle are confirmed first in the enquiry.
What is a Risley pair?
Two wedge prisms in rotating mounts. Rotating them relative to each other steers the deviated beam around a cone, giving two-axis beam steering with no moving mirrors.
What should my enquiry include?
Required deviation or wedge angle, aperture, glass preference and quantity.
Wedge Prisms in Beam Steering Systems
A Risley pair needs two wedges of matched deviation in rotation mounts with readable angular scales, because the steering solution — the combination of the two rotation angles that points the beam at a target — is computed from their equality. A single wedge used as a compensator needs its deviation marked relative to a stated edge direction, or the assembly technician cannot clock it into the mount correctly. Deviation also scales with wavelength through the glass's dispersion, mildly but measurably, so laser systems working at two wavelengths should expect slightly different deviations at each and say both wavelengths in the enquiry. These are the details that make wedge prisms a system component rather than a catalogue curiosity, and they cost nothing to include in the first message beyond the minute it takes to write them down.
Request a Quotation
Tell us the component, material, dimensions and coating you need. Pricing and lead time for your specification are confirmed in the written quotation.