Roof prisms can rotate and invert images and deflect light at 90°. They are suitable for telescope eyepieces and any optical instrument that needs to flip the image from the objective lens, turn the right side, and bend it at 90° to maintain the correct visual direction.

The key to roof prisms is the existence of a roof surface. The so-called roof surface is a roof-shaped reflective surface sandwiched by two reflective surfaces in the light path. The edges of the two surfaces are in the middle of the light path, so some roof prisms can see a dividing line in the middle, which can actually be understood as splitting the light beam into two halves and then splicing them together.

The reflective surface of a roof prism usually relies on total internal reflection, but it can be coated to increase the working angle range of the prism. For a roof prism, the 90° angle between the two faces must be very accurate to 90°, otherwise the image quality will be affected.

AOS Optics can provide custom roof prisms in various materials, including UV Fused Silica for UV applications.