Dove Prism: Image Rotation, Specs & Applications
A dove prism is a truncated right-angle prism used to invert an image without changing the direction of the beam. Its standout property is rotational: turn the prism around its long axis, and the transmitted image rotates at twice the prism's rotation rate — which makes it a compact, purely optical image rotator.
Key Specifications at a Glance
| Parameter | Typical Value |
|---|---|
| Substrate | N-BK7, UV fused silica |
| Length | 10 mm–150 mm |
| Aperture | 5 mm–50 mm |
| Surface flatness | λ/4–λ/10 at 633 nm |
| Surface quality | 60-40 (standard), 20-10 (precision) |
| Coating | AR-coated entrance/exit faces; bottom face uncoated (TIR) |
How It Works
Light enters one angled end face, undergoes total internal reflection off the long bottom face, and exits the opposite angled face. Because there's a single reflection, the image comes out inverted top-to-bottom but not flipped left-to-right.
Why Use One
Rotating a dove prism is a simple way to rotate an image or beam pattern without moving any other part of the optical system — and because the image rotates twice as fast as the prism, a small rotation stage gives a large rotational range.
Applications
- Image rotators in beam-shaping and laser systems
- Interferometry and astronomy instruments
- Pattern recognition and machine vision
Buying Tips
Dove prisms need a minimum beam diameter relative to their length — too short a prism relative to the beam causes vignetting or double images at the edges. Confirm your beam diameter against the prism's clear aperture and length before ordering; a wider beam needs a longer prism.
