This filter is necessary to observe the fluorescence emitted by applying excitation light to a sample stained with a fluorescent dye.
In order to carry out fluorescence observation, not only a light source but also a fluorescence filter and an objective lens that transmit only specific light are required.

[Fluorescence filter (abbreviation: BA)]
An individual element that makes up an optical device or optical system that efficiently transmits fluorescence emitted from a sample and removes other unnecessary light.

[Excitation filter (abbreviation: EX)]
Individual elements that make up an optical device or optical system that extracts the light (wavelength) required to excite a fluorescent substance from a light source