Filters for Fluorescent Measurements

Filter Combinations for the Fluorescence Imaging Method

Operating Principle of a Fluorescence Filter Cube:

The incident light passes through the excitation filter of a fluorescence filter cube. The filtered light is then reflected by the dichroite and hits the fluorophore. Now, the longer wavelength fluorescent light passes through both the dichroite and the emission filter to reach the detector. The purpose of the emission filter is to block the scattered excitation light. As a result, you see a bright fluorescence against a dark background.

Each of the three components must meet specific requirements.

Excitation Filters

The excitation filter reflects all the wavelengths of the light source that do not lie within the excitation range of the fluorophore. Transmittance in the passband must be as high as possible in order to achieve bright, brilliant images.

Dichroic Beam Splitters

A dichroic beam splitter guides the largest possible amount of excitation light to the sample while also directing the highest possible proportion of the fluorescence signal to the detector.

Emission Filters

The emission filter is the counterpart to the excitation filter. This bandpass or longpass filter is designed to transmit as much fluorescence light as possible to the detector.

Our hard coatings allow for higher quality designs with transmission values up to >98%, high blockings of >OD 6 and very steep edges. These ULTRA designs optimize instrument performance and provide extremely clear images and high contrast. For this purpose, we offer filters with tight wavelength tolerances, very steep edges, increased blocking values and one of the highest transmittances on the market.

Selecting the Right Set of Filters:

In fluorescence imaging, excellent results can only be achieved with the right choice of filters. In doing so, the user must consider the respective system as well as the specific application. The spectral requirements are defined by light source, fluorophore and detector. Filter dimensions depend on the manufacturer and model of the microscope - e.g..: Nikon (Labophot, Diaphot or Eclipse series), Olympus (BH or BX series), Leica (DM or Ploemopak series) and Zeiss (Axiovert, Axioskop or Axioplan series).