The so-called narrow-band filter is subdivided from the band-pass filter, and its definition is the same as that of the band-pass filter, that is, this kind of filter allows the optical signal to pass through in a specific wavelength band, but deviates from the band outside the band. Optical signals on both sides are blocked, and the passband of the narrowband filter is relatively narrow, generally less than 5% of the central wavelength value.
The main function of the narrow-band filter is to pass light of a specific wavelength and to reflect (or attenuate) light of other wavelengths. The half-wave width is usually controlled at 20nm or less and can be used in ultraviolet, visible, near-infrared, and far-infrared wavelengths. The narrow-band filter is made of multi-layer hard film by ion-assisted deposition of nanomaterials through high vacuum evaporation, and the film has good density. The imaging definition is high. Monolithic type does not use glue-plated hard film, long service life, wavelength positioning ion evaporation, small temperature drift, high penetration rate, and high cut-off depth.
1. Monolithic type does not use glue, hard coating, long service life, wavelength positioning, ion evaporation, small temperature drift, and strict production process control.
2. The product size and optical index error are small, imported ultra-thin optical glass, high transmittance, good smoothness, small thickness tolerance, good flatness, and other optical characteristics, using imported coating equipment ion sputtering coating process.
3. The narrow band optical filter has the characteristics of high film firmness, good spectral uniformity, and strong center wave stability.
Narrowband optical filters are used in fluorescence analyzers, microplate readers, cable TV upgrade equipment, transmission equipment, barcode scanning, infrared electronic whiteboards, infrared SHE cameras, infrared touch screens, iris recognition, infrared medical equipment, infrared ink recognition, iris recognition, and face recognition sensor system. Besides, it also can be used in handheld infrared laser rangefinders, laser rangefinders, optical instruments, medical and health equipment, and testing instruments.
Both of them cause the image to be colored and seriously affect the image quality, even in the paraxial region. People define the wavelength in the direction of diffraction this way: the wavelength from the direction of diffraction on the grating to the direction of reflected light on the groove surface is the shining wavelength. This feature can be used to align the center wavelength within a certain range. The introduction and application of electronic computers have promoted the development of the optical design. The monitoring distance is now up to 1500-5000 meters. The optical filter film determines the object a long distance from the target than the infrared thermometer. An infrared pyrometer according to the principle can be divided into a monochromatic pyrometer and a two-color pyrometer (radiation colorimetric pyrometer).