Figure 9-9. Principles of Light Polarization
Prisms. Optical prisms are blocks of glass, of many shapes, with two or more highly polished non-parallel flat
surfaces that reflect or refract light, and which are especially designed and ground to perform various functions. They are
used separately or in pairs to change the direction of light from a few seconds of arc (measuring wedge) or up to 360
degrees (Porro prism system).
The Amici or roof angle prism, as shown in figure 9-10 consists of a roof edge formed upon the long
reflecting face of a right angle prism. It is used in elbow and panoramic telescopes to erect the image
and bend the line-of- sight through a 90 degree angle.
Figure 9-10. Amici Prism
Change 2 9-7