Fluorescent filters generally contain a combination of three pieces, namely, an excitation filter, an emission filter, and a dichroic mirror.
Excitation Filter (Exciting Filter, Exciter Filter,Excitation Filter ): In fluorescence microscopy, only the wavelength of the excitation fluorescence can pass through the filter. In the past, short-wavelength filters were used, but nowadays, band-pass filters are basically used. An arrow is engraved on the housing to indicate the direction of propagation of the recommended light.
Emitting Filter (Emitting Filter,Emission Filter ,Barrier Filter, Emitter): selects and transmits the fluorescence emitted by the sample, other range light cutoff. The wavelength of the emitted light is longer than the wavelength of the excitation light (closer to the red color). A bandpass filter or a long-wavelength pass filter can be selected as the emission filter. Its housing is engraved with arrows indicating the direction of propagation of the recommended light.
Dichroic Mirror (Dichroic Mirror, Dichroic Beamsplitter, Dichromatic Beamsplitter): also known as dichroic filters or dichroic mirrors. It is placed at a 45° angle to the light path of the microscope. The filter reflects one color of light (excitation) and transmits another color of light (emission), with the reflectance of the excitation light being greater than 90% and the transmittance of the emission light being greater than 90%. The non-transmissible portion of the spectrum is reflected rather than absorbed. Filters are also known as dichroic filters because the colors of transmitted and reflected light are complementary to each other.
Fluorescence Filters (Fluorescence Filters) is the abbreviation of fluorescence imaging filters, is used in biomedical and life science instruments, the key components, the main role is in the biomedical fluorescence inspection and analysis system to separate and select the excitation light of the substance and the emission of fluorescence characteristics of the band spectrum. Usually requires the filter cut-off depth in OD5 (optical density, OD = -lgT) or more. The core requirements for filters used in fluorescence detection systems are high cutoff steepness, high transmittance, high positioning accuracy, high cutoff depth and excellent environmental stability.