Narrowband Filter

Features of Narrowband Filter

• Center Wavelength: Refers to the wavelength at the center of the passband, usually the operating wavelength of the instrument or device.

  
  

• Bandwidth (Full Width at Half Maximum, FWHM): The distance between the two positions in the passband where the transmittance is half of the peak transmittance.

  
  

• Peak Transmittance: The highest transmittance within the passband of the bandpass filter.

  
  

• Cutoff Range: The wavelength range outside the passband that is required to be blocked.

  
  

• The working principle of narrowband filters is based on the interference and diffraction effects of light. By coating multiple layers of optical films with different refractive indices and thicknesses on a glass substrate, these films are stacked together in a specific order to form a special interference structure. As light passes through these films, it undergoes reflection and transmission between different layers, creating interference phenomena. By precisely controlling the thickness and refractive index of the films, only light within the target wavelength range is enhanced and transmitted through the interference process, while light of other wavelengths is weakened or reflected.

  
  

• Narrowband filters are widely used in various analytical instruments, detection devices, biometric systems, and laser purification fields. For example, in photography, narrowband filters can correct the color contrast of objects, making the colors of various objects meet ideal requirements. In black-and-white photography, narrowband filters effectively adjust the contrast and tonal range of objects, ensuring that the colors of various objects meet the desired contrast and tonal requirements.

Specifications of Narrowband Filter