Interference-coated long-pass filter

Interference-coated long-pass filters are optical components designed based on the principle of light interference. They form a precise multilayer structure by alternately depositing dozens to hundreds of high and low refractive index dielectric thin films on the surface of an optical substrate. Their working principle is as follows: light of specific wavelengths undergoes constructive interference at the film interfaces, resulting in high transmission. Light with wavelengths shorter than the cutoff wavelength, on the other hand, is reflected or absorbed due to destructive interference, thereby allowing long-wavelength light to pass through and blocking short-wavelength light. These filters are characterized by steep passband edges, high