5.1 Prism Design and Analysis
More optical tools are available for the analysis of prism and mirror systems than for the design of new systems. Some questions to be considered when approaching the design of a prism for an optical system are:
- Is the prism to be used in an imaging optical system, or as an illumination control element, or both?
- For imaging applications, what is the required orientation of the viewed or projected image? Does the image shape need to be preserved-e.g., no linear magnification?
- Can an existing design, preferably one available from a commercial supplier, be used?
- Can the design be fabricated economically?
- Is the required prism a single or compound element?
- Are compound prisms air-spaced or bonded?
- Are surface coatings required-e.g., antireflection or beam-splitting?
- Does the prism need to be achromatic?
- Will the prism be used in convergent or divergent light?
- What aperture size is required?
- What is the wavelength range of interest?
- Are there size and weight limitations?
- What are the mounting tolerance requirements?
- What are the prism material clarity requirements, angular accuracy of faces, and surface smoothness?
- What is the thermal environment?
There is an extensive library of prism designs in the literature that may provide the requirement of your optical system. Many times, these designs can be modified by a change of glass material or the addition of special coatings. Often two or more existing prisms can be combined in series.