Difference between narrowband and bandpass filters

The main difference between narrow band filters and bandpass filters is the range of wavelengths over which they pass light.

Narrowband filters pass a very narrow range of wavelengths, usually below 20 nm. This design makes narrow-band filters very effective at blocking light outside of a specific wavelength range, so they are useful in applications where precise wavelengths are required, such as spectral analysis, peak detection, and measuring wavelength stability.

In contrast, bandpass filters pass a wider range of wavelengths, typically above 20 nm. This design allows bandpass filters to pass multiple fields or wavelengths of light at the same time, which is why they have a wide range of applications in fields such as machine vision, medical and environmental protection.

In addition, narrow band filters usually use all-dielectric hard coating technology and dielectric interference principle, and their optical performance is independent of the substrate's thickness, making them more convenient to be built into the imaging system of the instrument. Bandpass filters have a wide range of applications in a relatively wide frequency range, such as video cameras, cameras, etc., due to their wide range of passing frequencies.

Narrowband filters can be applied to the imaging system to improve its optical performance and be effectively applied. By using special optical material substrates, the problem of moldy and unstable optical performance of absorbing synthetic glass in the traditional sense is solved.

A narrowband filter is an optical element that is mainly used to reflect (or attenuate) light of other wavelengths by light of a specific wavelength. The half-wave width is usually controlled below 20nm and can be in the ultraviolet, visible, near-infrared wavelengths, and far-infrared wavelengths. Narrowband filters are made of multilayer rigid films of nanomaterials deposited by ion-assisted deposition under high vacuum, with good densification and high imaging clarity. No monolithic hard coatings, long service life, high penetration rate and high cut-off depth.

Bandpass filters allow optical signals in a specific wavelength band to pass through, while optical signals on both sides of the band are blocked. The passband of a bandpass filter is relatively wide, with a half-bandwidth typically above 40 nm. A narrow-band filter is a type of bandpass filter and has the same definition as a bandpass filter. It allows a specific band of optical signals to pass, while the optical signals on both sides outside this band are blocked, but the narrow band filter is relatively narrow.