Notch filter

Notchfilter

Notch filters are used to block a narrow wavelength range. In Raman spectroscopy, this allows Stokes-scattered (long wavelengths) and anti-Stokes-scattered (short wavelengths) light to be observed while the laser line is blocked at the same time. A high degree of transmission in the passband and deep blocking on the seed laser line (OD > 6) provides a stronger signal with less background noise.