Why would you use a plastic prism?

Answer 1

I take it you mean "instead of glass / crystal" as opposed to why use a prism at all.

1. Cheaper - Depending on the material and specification, a simple prism can be made on an extrusion basis and simply sliced to length making for a very inexpensive product.

2. Lighter - many plastics are much less dense than glass - if the task can be handled with plastic and weight is an issue, glass would be a poor alternative.

3. Stability - although glass may have a higher survival rate (temperature), a prism that must be exposed for some reason may well be more vulnerable to chipping than plastic

4. Transmission / Reflection properties. Although most of the visible spectrum will pass well through all clear glass / plastics, as you begin to approach IR and most especially UV, the material have VERY different properties. UVB and UVC for example being blocked by most glass - hence UVC lamps use quartz rather than regular glass.

To give more information, it would help to know if there is a specific focus to your question - eg: application specific - in which case other factors may or may not be worth mentioning.

Answer 2

Plastic prisms are lightweight, durable, and affordable compared to glass prisms. They can be used in educational settings for teaching about light refraction or in Photography to create artistic effects. They are also safer to use, as they are less likely to shatter if dropped.