Filter can alter the characteristics of a beam of
light. Absorption and particularly wavelength selective absorption
is an important factor in the function of the filters. Filter can
change the overall intensity of the beam without affecting its
spectral content (e.g., neutral density filters). It can also
change or separate the spectral content of the beam through
wavelength-selective absorption or reflection (e.g., high-pass,
low-pass, edge, dichroic and interference
filters).
Advance Optics provide many kinds of optical
filters
including Colored Glass
Filter,Interference
Filter,Neutral Density
Filter,
etc.
You
can search AdvanceOptics on google to get web and
company information.