The 548 nm filter is a green visible light narrowband filter with a center wavelength fixed at 548 nm (FWHM 10–40 nm), peak transmittance >90%, and out-of-band blocking depth ≥OD4. It employs a multilayer hard coating ion sputtering process, resulting in dense film layers, high damage threshold, and surface accuracy of 40-20. It only allows green light to pass through while effectively blocking violet, blue, yellow, and infrared stray light. Widely used in fluorescence microscopy, flow cytometry, colorimetric analysis, machine vision, and laser protection, it is compatible with dyes such as Cy3 and Alexa Fluor 532, offering high imaging contrast and low background noise. It serves as a core component in biochemical detection and precision optical systems.