What are corner cube retroreflectors? Today, let’s take a brief understanding. The corner cube retroreflector is generally called Paul prism or Pro prism. It is an optical element used in optical instruments, and it is a refracting prism used to modify the image orientation.
The corner cube retroreflector is an isosceles right-angle prism formed of glass, the end plane faces the right angle. In use, the light enters from the largest rectangular surface in the prism, passes through the two total reflections of the inclined surface, and then penetrates the original incident plane. Because light only enters and exits in a normal state, the prism has no effect of dispersion. However, the image passing through the corner cube retroreflector will be flipped 180° and will enter in the original direction.
The entry direction of the corner cube retroreflector has also changed by 180°, but because the image has been reflected twice, the handedness does not change. Corner cube retroreflectors are most often used in pairs with a combination of double corner prisms. The second prism is rotated 90° relative to the first. Let the light pass through the two prisms arranged in this way. The net effect of the prism system is that the incident light is parallel to change the direction of travel, the image is rotated 180°, and the eccentricity remains unchanged.
The bicubic prism system is suitable for changing the image direction of small optical telescopes (arrangement of image reconstruction system), especially in many binoculars, providing image reconstruction and longer optical path folding, effectively shortening the distance between the objective lens and the eyepiece. Generally, in the combination of double-corner prisms, two prisms are glued together, and excess parts are cut off to reduce weight and size. The Paul prism alone can also be regarded as a roof prism, but it is not used in binoculars. A variant of the double Paul prism is the Paul Abbe prism.