A prism is a solid glass optic shaped and polished to have geometrically and optically significant surfaces. These surfaces’ angles, positions, and numbers define the type and function of the prism. Prisms have various applications, one of which is dispersing white light into its component colors, as demonstrated by Sir Isaac Newton. They are also used to bend or fold light within a system, change the orientation of an image, and combine or split optical beams with partially reflecting surfaces.
Prisms can be modeled as a system of plane mirrors to simulate light reflection within the prism medium. This characteristic makes prisms valuable for replacing mirror assemblies, reducing alignment errors, increasing accuracy, and minimizing system complexity and size.
Manufacturing prisms requires strict tolerances and accuracies due to their variable shapes, sizes, and the number of surfaces. Automated large-scale prism manufacturing is impractical due to these factors and the typically low quantities of high-precision prisms needed.
The manufacturing process involves obtaining a glass block, grinding it with a diamond wheel to near-finished form, then smoothing and polishing it to the specified surface flatness. Chamfering dulls sharp edges, and the prism is cleaned, inspected, and coated with anti-reflection or metallic mirror coatings if necessary. Throughout manufacturing, each surface is continually adjusted and secured using blocking or contacting methods, depending on the precision required. Blocking involves hot wax, while contacting bonds clean glass surfaces through their Van Der Waals interaction, ideal for high precision tolerances.