A right angle prism works in two distinct modes. In folding mode, the hypotenuse face reflects by total internal reflection and the prism turns a beam through 90 degrees or folds a path back on itself, with no coating needed on the reflecting face — the general behaviour of the form, set out here as background; no folding-prism listing is separately recorded in the catalogue behind this site. In splitting mode, a partially reflective coating on the hypotenuse turns the prism into a beam splitter. The documented catalogue records one stock listing of that kind — a high-reflective right-angle prism with a dielectric coating, sold as a light splitter prism with a 1-piece minimum; note exactly what the record holds: the listing's name and its dielectric coating. The record does not state which face carries the coating, so the coated face is confirmed in the quotation.
The 90-degree-prism geometry is also the building block inside porro and penta assemblies, periscope pairs and the fold sections of compact viewing instruments. Because the part is a single piece of glass, it holds its angle through handling and temperature in a way a pair of aligned mirrors does not.
Documented Right Angle Listing
| Listing (storefront) | Documented detail | MOQ |
|---|---|---|
| Stock right angle light splitter prism | High-reflective dielectric coating, as named in the listing — the record does not state the coated face | 1 piece |
| Right angle prism group | A group entry within the documented prism families; no individual folding-prism listing is recorded beyond the stock splitter above | Per quotation |
Specifying a Right Angle Prism
Leg length (the equal sides of the triangle) is the primary dimension; glass, and the coating decision per face, are the first fields the enquiry asks for. State plainly which mode you need: uncoated hypotenuse for TIR folding, or a coated hypotenuse with a stated split ratio for splitting. If the prism works at 45-degree incidence inside a polarisation-sensitive system, say so in the enquiry — coating behaviour at that angle is part of the quotation discussion. Buyers comparing geometries can also review the wedge prisms for small-angle deviation and the family overview on the optical prisms page.
Frequently Asked Questions
What is the minimum order?
1 piece on the documented stock splitter prism listing — evaluation quantities are straightforward.
Does the reflecting face need a coating?
Not for folding: the hypotenuse reflects by total internal reflection. A coating is needed only when the prism must split the beam; the documented stock splitter listing is recorded by its name and its dielectric coating, and which face is coated is confirmed in the quotation.
Can the prism split by polarisation?
No polarising beam splitter listing is recorded in the source catalogue. State the split behaviour you need; availability and construction must be confirmed in the quotation.
Tolerances That Show: Angle and the Hypotenuse
Two specification items belong at the head of a right angle prism enquiry. The first is the 90-degree angle tolerance: the deviation of the output beam is twice the error in the prism's right angle in the sensitive plane, so alignment-grade work should state the deviation the system can absorb rather than accepting a default grade. The second is the state of the hypotenuse face. In folding service it works by total internal reflection, which is total only above the critical angle and only while the face stays clean — a fingerprint or a cement layer on that face frustrates the reflection locally, which is why TIR prisms are mounted clear of the hypotenuse and why a splitter requirement is specified as its own form rather than assumed from the folding prism. Neither point appears on a headline listing; both belong in a serious enquiry, and stating them is what separates a prism bought for an instrument from a prism bought for a drawer.
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.