Fluorescence filter is the abbreviation of fluorescence imaging filter. It is a key component used in biomedical and life science instruments. Its main function is to separate and select the characteristic bands of excitation and emission fluorescence of biomedical fluorescence detection and analysis system. spectrum. The filter cut-off depth is usually required to be above OD5 (optical density, OD=-lgT). The core requirements for filters used in fluorescence detection systems are high cut-off steepness, high transmission, high positioning accuracy, high cut-off depth, and excellent environmental stability.
Fluorescent filters typically comprise a combination of three, an excitation filter, an emission filter, and a dichroic mirror.
Exciting filter ( Excitation filter) In a fluorescence microscope, only the filter that excites the wavelength at which fluorescence can pass. In the past, short pass filters were used, and bandpass filters are now basically used. The housing is engraved with an arrow indicating the direction of propagation of the recommended light.
Emitting Filter (Emission Filter) elect and transmit the fluorescence emitted by the sample, and other ranges of light are cut off. The wavelength of the emitted light is longer than the wavelength of the excitation light (closer to red). A band pass filter or a long pass filter can be selected as the emission filter. The housing is engraved with an arrow indicating the direction of propagation of the recommended light.
Dichromoic Mirror, Also known as dichroic filter or dichroic mirror. Placed at a 45° angle to the optical path of the microscope. This filter reflects one color of light (excitation light) and transmits another color of light (emitted light), the reflectance of the excitation light is greater than 90%, and the transmittance of the emitted light is greater than 90%. The impenetrable portion of the spectrum is reflected rather than absorbed. The color of the filter under the transmitted light and the reflected light is complementary to each other, and is also called a dichroic filter.