A new ASE filter is presented, consisting of 20 dispersion prisms and two s
patial filters. The transmission of the filter is measured with a ring-dye
laser. The 1% width of the filter is 0.23 nm. The transmission is approxima
tely 80% for the transmitted wavelengths. The rejection is in the order of
10(-5). The transmission profile is calculated from the index of refraction
of the prisms, Snell's law, and the laser waist diameter. The calculated p
rofile fits the measured profile very well.