Filter sets are optimized for the listed fluorophore. For alternative fluorophore compatibility information, see the Fluorophores tab.
Click to Enlarge Thorlabs' filter cubes feature labels for identifying installed filters.
Drop-in Filter Cubes with Pre-Installed Fluorescence Filter Sets for Select Nikon and Olympus Microscopes (See Table Below)
Filters Optimized for Common Fluorophores (See Table to the Right)
Pre-Installed Filters Minimize Handling of Bare Optics
Durable Aluminum Filter Cube Body
Side Labels for Marking Installed Filters
This page offers Thorlabs' microscope filter cubes with pre-installed fluorescence filter sets. Choose from 13 available imaging filter sets; each is optimized for a specific fluorophore (see table to the right for options). These filter sets can also be used with other fluorophores (see the Fluorophores tab for more information). Four filter cube body options are available for each filter set; they are compatible with select Olympus and Nikon fluorescence microscopes (see the table below for microscope compatibility).
Filter Design Our filters are manufactured to high-performance optical specifications and designed for durability. They are produced via multiple dielectric layers deposited on a high-precision, fused silica substrate. The substrate is ground and polished to ensure that the highest possible image quality is maintained. The resulting hard-coated optics consist of filter layers that are denser than those obtained from electron beam deposition techniques, and which reduce water absorption while greatly enhancing durability, stability, and performance of the filter. Each filter layer is monitored during growth to ensure minimal deviation from design specification thickness, ensuring overall high-quality filter performance.
Installation of Filters into the TLV-U-MF2 Cube
Microscopy Filter Cubes These cubes feature a spring plate retention mechanism for the dichroic mirror that results in lower optic stress for improved imaging. Our design also offers an all-aluminum cube body, simplified optic mounting, and three labels for writing information about installed filters. Each cube is also engraved with the empty cube item number. Refer to the table below to view which filter cubes are compatible with which microscope.
Although one filter set is pre-installed into each filter cube, users can easily swap the installed filters. The cubes are compatible with the following filters: one excitation filter (Ø25 mm, up to 5 mm thick), one emission filter (Ø25 mm, up to 3.5 mm thick), and one dichroic mirror (up to 25.2 mm x 36.0 mm x 1.1 mm). Optics can be mounted, aligned, and swapped out easily as illustrated in the video to the right. For detailed assembly instructions, please refer to the assembly manuals in the table below.
When these cubes are placed in a filter cube turret, it is important to balance the weight. To ensure longevity of a motorized filter cube turret and prevent unnecessary wear, please place filter cubes opposing each other to maintain balance.
MDF-YFP filter set transmission graph. Note the dichroic mirror (green) reflects light in the excitation wavelength range (blue), and transmits light in the emission wavelength range (green).
Filters for Fluorescence Microscopy
Fluorophores A fluorophore is a molecule or portion of a molecule that is capable of producing fluorescence. When light of the appropriate frequency necessary to excite a molecule from its ground state to an excited state is present, excitation will occur. However, once in an excited state, the molecule will be unstable. After some short period of time (typically 10-15 to 10-9 s), a photon will be released, thereby enabling the molecule to return to a lower energy state. The emitted radiation will be at a longer wavelength (lower energy) than the absorbed radiation due to the loss of energy through various mechanisms such as vibrations, sound, and thermal energy.
A single fluorophore can be continually excited unless it is destroyed by photobleaching (i.e. the nonreversible destruction of a fluorophore due to photon-induced chemical damage or covalent modification). The average number of excitation and emission cycles that a particular fluorophore can undergo prior to photobleaching depends on its molecular structure and the local environment; some fluorophores bleach quickly after emitting only a few photons while others are far more robust and can undergo thousands or even millions of cycles before bleaching occurs.
Filters for Fluorescence Microscopy The experimental setup to the right shows the typical filters used for epi-fluorescence microscopy, a form of microscopy in which both the excitation and emission light travel through the microscope objective. By carefully choosing the appropriate filters and mirrors for a given application, the signal-to-noise ratio can be maximized. As shown in the schematic to the right, three types of filters are used to maximize the fluorescence signal while minimizing the unwanted radiation. Each optical element is discussed below.
Excitation Filter The excitation filter only allows a narrow band of wavelengths to pass through it, around the peak fluorophore excitation wavelength. For example, as shown in the graph to the right, the bandpass region corresponding to greater than 90% transmission for the Yellow Fluorescent Protein (YFP) Excitation Filter (MF497-16) is 489 - 505 nm; incident radiation outside of this range is either partially (for regions near the transmission region) or totally (for regions further from the bandpass region) blocked by the filter.
Dichroic Mirror Dichroic mirrors are designed to reflect light whose wavelength is below a specific value (i.e. the cutoff wavelength) while permitting all other wavelengths to pass through it unaltered. In a microscope, the dichroic mirror directs the proper wavelength range to the sample as well as to the image plane. The cutoff wavelength value associated with each mirror indicates the wavelength that corresponds to 50% transmission. For example, as shown in the graph to the right, the cutoff wavelength for the Yellow Fluorescent Protein (YFP) Dichroic Mirror (MD515) is ~515 nm. The Specs tab provides information on wavelength ranges corresponding to ≥ 90% average reflectance and transmission for each type of dichroic mirror.
By placing one of these mirrors into the experimental setup at 45° with respect to the incident radiation, the excitation radiation (shown in blue in the above right schematic) is reflected off of the surface of the dichroic mirror and directed towards the sample and microscope objective, while the fluorescence emanating from the sample (shown in red in the above right schematic) passes through the mirror to the detection system.
Although dichroic mirrors play a crucial role in fluorescence microscopy, they are not perfect when it comes to blocking unwanted light; typically, ~90% of the light at wavelengths below the cutoff wavelength value are reflected and ~90% of the light at wavelengths above this value are transmitted by the dichroic mirror. Hence, some of the excitation light can be transmitted through the dichroic mirror along with the longer wavelength fluorescence emitted by the sample. To prevent this unwanted light from reaching the detection system, an emission filter is used in addition to the dichroic mirror.
Emission Filter An emission filter serves the purpose of allowing the desirable fluorescence from the sample to reach the detector while blocking unwanted traces of excitation light. Like the excitation filter, this filter only allows a narrow band of wavelengths to pass through it, around the peak fluorophore emission wavelength. For example, as shown in the graph to the right, the bandpass region corresponding to greater than 90% transmission for the Yellow Fluorescent Protein (YFP) Emission Filter (MF535-22) is 524 - 546 nm; incident radiation outside of this range is either partially (for regions near the transmission region) or totally (for regions further from the bandpass region) blocked by the filter.
Acceptable - Actual performance depends on individual experimental conditions.
Compatible - Ideal, or nearly ideal, performance under most experimental conditions.
Optimized - Optimal performance under all experimental conditions.
a. Absorption and emission spectra are unavailable if any is red.
The table below displays all of the fluorophores that are compatible with our filter sets. The filter set item numbers are listed across the top row and the fluorophores are listed down the first column. Scroll through the table to view fluorophore compatibility with our filter sets.
Click on the below to view the filter set transmission with the absorption and emission spectra of the fluorophore. The key to the right details the meaning of all check marks in the table below. Please note that absorption and emission spectra are unavailable if any is red.