Re: How exactly does a short wave pass filter work?

A short wavelength pass filter works exactly as the name suggests. It will selectively pass the short wavelengths of light and filter out the longer wavelengths of light preventing them from passing through. This is done by manufacturing the filter from materials that have the appropriate transparency in the wavelength region of interest. It does not however alter the wavelength of the incident light in any way. It just allows light of the shorter wavelengths through.

There are many types of optical filters and each has different characteristics. Band-pass filters like the one you suggest typically will have a gradual "roll-off" meaning that there is not a fixed sharp cutoff wavelength, but rather the attenuation with wavelength will gradually increase as the wavelength gets longer. This also depends on the materials used and the resulting optical properties.

[note added by MadSci Admin: There are optical materials which can shift wavelengths of the electromagnetic radiation incident on them, but these are nonlinear materials which are usually used in frequency doubling applications.]