Use CWL 266nm with 10nm FWHM for 266nm fourth-harmonic laser line selection, source cleanup, or detector-side isolation.
266nm is commonly generated as the fourth harmonic of 1064nm Nd:YAG or Nd:YVO₄ lasers. For this source, the key specs are CWL match near 266nm, FWHM, transmission at 266nm, OD blocking over the unwanted wavelength range, and suitable DUV coating performance for the beam condition.
Broadband DUV source filtering
Use CWL 266nm with 40nm FWHM for broadband DUV source filtering when the setup needs more transmitted UV signal around 266nm.
For deuterium lamps, xenon lamps, or broadband UV sources, the filter extracts a DUV band from a wider spectrum. A 40nm FWHM option is more practical when the system needs usable UV signal for illumination, testing, or detector-side measurement.