Porro prism is a type of reflection prism which can be used to alter the orientation of an image. Light enters the large face of the prism, then hits on the roof, by total internal reflection twice from the roof, the beam exits again through the large face. An image traveling through a Porro prism is rotated by 180deg but not inverted.
| Dimension Tolerance | +0/-0.2mm |
| Surface Quality | 60/40 scratch and dig |
| Clear Aperture | >80% |
| Flatness | <λ/[email protected] |
| Wavefront Distortion | <λ/[email protected] |
| Deviation | 180°±10 arc seconds |
| Roof Angle Tolerance | <5 arc seconds |
| Chamfer | Sharp roof, other protective chamfered |
| AR Coating | None, available |
