Filters and mounts
176
Goldeye G/CL Technical Manual V4.2.0
Stopband
The stopband is the range of wavelengths over which unwanted signals are
attenuated. Bandpass filters have two stopbands, one above and one below the
passband. As a rule, the end of the stopbands is not precisely defined.
CWL (=central wave length)
The wavelength at the center of the filter’s passband. This wavelength is the
arithmetical mean of the Cut-on and Cut-off wavelengths.
Cut-on and Cut-off wavelength
The Cut-on wavelength is the wavelength within the transition slope from rejection
to pass where the transmittance is at 50 percent of peak transmittance. The
Cut-off wavelength is the wavelength within the transition slope from pass to
rejection where the transmittance is at 50 percent of peak transmittance. The
range between both wavelengths is called the
FWHM
.
Figure 49: Example of a response curve of a bandpass water filter
