Filter sets consisting of a compatible excitation filter, emission filter, and dichroic beam splitter are required to analyze fluorescence under a microscope. These components are also available individually.
Components for Fluorescence Measurements
Accessory for fluorescence microscopy
Bandpass filters transfer as much energy from the light source into the absorption band as possible and ideally only into the absorption band.
Dichroic Beam Splitters
For one, the dichroic directs as much excitation light onto the sample as possible and, for another, as much fluorescence light onto the detector as possible.
The Emission filters transfer as much fluorescence energy as possible onto the detector.
- QM: With surface-coated QuantaMax designs on single substrates, a very high transmission is achieved at minimal edge drifts.
- 3rd: The 3rd Millennium series filters are based on ALPHA Gamma Technology.
- AE: AE filters based on ALPHA Epsilon technology. They exhibit very steep edges that can be defined very precisely. In addition, a very high blocking – theoretically up to OD10 – can be achieved.
- DF: Discriminating filters consist of 6 high and low refraction interference layers resulting in an almost rectangular bandpass with very steep slopes that block with OD 6 outside of the passband.
- WB: Wide-band filters may consist of 4 or 5 cavities. This design allows for an FWHM of approx. 30 nm up to several hundred nm.
- NB: Narrow-band filters consist of 2 cavities and typically have an FWHM of between 0.2 nm and 8 nm.
In a fluorescence filter cube, the incoming light passes the excitation filter. The filtered light is reflected by the dichroic filter and falls on the fluorophore. The longer-wave fluorescence light then passes the dichroic filter and the emission filter to subsequently reach the detector. The task of the emission filter is to block dispersed excitation light. The result is an illuminating fluorescence with a dark background.
The imaging fluorescence requires of the user the correct filter selection. An optimization has to take into account the corresponding system as well as the application at hand. The light source, the fluorophore, and the detector define the spectral requirements. The employed model and type of the microscope determine the filter dimensions.
Compatible for Standard Microscopes:
Nikon (e.g., Labophot, Diaphot, and Eclipse series), Olympus (e.g., BH and BX series), Leica (e.g., DM and Ploemopak series), and Zeiss (e.g., Axiovert, Axioskop, Axioplan series)
In the fluorescence filter sets an additional filter can be required that increases the blocking bandwidth (1150 nm for silicon) and, at the same time, reduces the heat input into the optical system. Many lamp housings and detectors have filters to block longer wavelengths. Standard sizes of IR blockers are 18 mm, 25 mm, and 32 mm.