I am making a spectrometer as my school project. It's main application will be analyzing the light emitted by various light sources. It measures visible, near IR and UVA/UVB radiation. I need it to be relatively weatherproof, so it needs to have some form of a window to protect the measuring modules from water, dust, debris etc.
I am concerned that passing light through a transparent material would cause a change in the spectrum. Are my concerns true, or are they false or too small to make a difference? Additionally, what would be the best material to use as a window? (the only material available to me right now are clear plastic sheets designed for use with printers, would that be at least marginally OK?)