The 222nm narrow-band filter is an optical component derived from band-pass filters, with its core function being to allow light signals within the specific 222nm wavelength band to pass while blocking light signals outside this band. Its key parameters are as follows:

• Center Wavelength (CWL): 222nm, which is the wavelength at the center of the passband and the core operating wavelength of the filter.
• Full Width at Half Maximum (FWHM): Typically 10nm-60nm, referring to the distance between the two points in the passband where the transmittance is half of the peak transmittance. Some products can be customized with a bandwidth of 10nm to meet high-precision requirements.
• Blocking Range: Covers 200-1100nm, including both short-wave blocking (wavelengths shorter than the center wavelength) and long-wave blocking (wavelengths longer than the center wavelength), ensuring effective blocking of non-target wavelengths.
• Blocking Depth (OD Value): Generally OD2-OD4, meaning the maximum allowable transmittance is 0.01%-1% (OD = -logT). Different applications have varying requirements; for example, fluorescence analysis requires OD4 or higher (T ≤ 0.001%), while general monitoring and recognition can be satisfied with OD2 (T ≤ 1%).