Narrow Band Filter

A narrow band filter (NBF) is an optical component that selectively allows light within a specific narrow wavelength range to pass through while effectively blocking other wavelengths. Its core principle typically relies on the interference effect of light. Through a precisely designed multi-layer dielectric film structure, light at the target wavelength undergoes constructive interference and transmits, whereas light at other wavelengths experiences destructive interference and is reflected or absorbed. Narrow band filters feature extremely narrow passband widths (usually less than 10 nm, and even down to sub-nanometer levels), high transmittance, and deep attenuation depth. They can accurately screen for specific wavelengths of light and are widely used in laser technology, spectral analysis, biomedical imaging, astronomical observation, and optical communication fields to enhance signal purity, suppress stray light, or achieve precise wavelength selection.