Rather than specify a parallelism value as a maximum angular deviation between the two surfaces of the window, wedged windows specify both a maximum and a minimum value for wedge angle. In addition, the nominal angular values are larger, because the purpose of these windows is to deliberately provide a noticeable angular deviation between the first and second surfaces of the window. In applications where fringing between parallel surfaces or coaxial reflections from the first and second surfaces are a problem, wedged windows offer a simple solution. They are also useful in transmission as wedge prisms. Plano Partial Reflectors Partial Reflectors are used in numerous laser and other optical applications in the UV, VIS, and IR regions of the spectrum.
Partial reflectors utilize one surface to reflect some specified fraction of incident radiation.
This surface is most often coated to produce the desired performance but may be uncoated. In this case the reflectivity is determined by the substrate index of refraction.