Maximum Filter Thicknesses
Excitation	5 mm
Emission	3.5 mm
Dichroic	1.1 mm

Click to Enlarge
Fluorescence filter sets can be easily mounted in the DFM Filter Cube (filters sold separately).

Features

Prealigned Fluorescence Filter Holder Within a 30 mm Cage Cube
Easily Swap Between Filter Sets Using Additional Inserts (Sold Separately)
Kinematic Design Provides Repeatable Alignment
Compatible with 30 mm Cage and SM1 Lens Tube Systems
Premounted Filter Cubes Available Upon Request

Click to Enlarge
The DFM features write-on labels for filter management.

Thorlabs' DFM Fluorescence Filter Cube is designed to hold a fluorescence filter set (dichroic mirror and excitation and emission filters) in a 30 mm cage-compatible cube for homebuilt microscopy applications. The light-tight filter cube consists of a base and top lid with an insert to hold the filter set.

The base unit (DFMB) has four SM1-threaded (1.035"-40) ports for compatibility with our SM1 lens tubes. Four 4-40 tapped holes surround each port for compatibility with our 30 mm cage system. The bottom surface contains an 1/4"-20 (M6) tap that is directly compatible with our Ø1" posts or Ø1.5" posts. The DFMB can also be directy attached to our Ø1/2" posts using a user-supplied 1/4"-20 (M6) set screw; alternately, an AE8E25E (AE4M6M) adapter can be used for compatibility with our Ø1/2" posts' 8-32 (M4) threaded studs. For details on all of the mounting features, see the mechanical drawings below.

The top with insert (DFMT1) is designed to hold a 25.2 mm x 35.6 mm dichroic mirror and two Ø25 mm filters (excitation and emission). The dichroic mirror is clamped in place using a design that provides uniform pressure without causing deformation to the mirror, and is locked in place using two 4-40 screws locked by a 3/32" hex key. Only light force is required to mount the filter; we recommend screwing in both screws most of the way before final tightening with a balldriver. The excitation and emission filters are held using the included SM1RR Retaining Rings, which can be tightened or loosened with our SPW606 or SPW602 Spanner Wrenches (sold separately). The SM1-tapped hole in the top plate’s emission port is oriented at a 3° angle with respect to the face of the bottom of the cube, thereby eliminating unwanted reflections.

Through an innovative kinematic design, filter sets can easily be swapped without requiring realignment. Additional tops and bases can be purchased separately. To help keep track of your filter sets, spaces are provided on the top to write the specific mirror and filters that are mounted in each cube.

Mounting Service
If any of our imaging filters is ordered at the same time as the DFM, Thorlabs will premount the filters at no additional charge. In order to take advantage of this option, please contact Technical Support prior to ordering.

Flourescence Filter Cube Mechanical Drawing

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Outer DFM Cube Dimensions

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Cube top (DFMT1) assembly. Parts A and B are fastened together with two 4-40 captive screws. There are four ports with SM1 threads for Ø1" or Ø25 mm optics. A 25 mm x 36 mm x 1.1 mm rectangular optic can be secured between parts A and B when they are fastened togehter.

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Posted Comments:

Poster: syim

Posted Date: 2013-05-14 21:45:07.743

I have tried DFM/M for a home-built confocal microscopy. But I found my focused laser beam having severe aberrations. I believe the two small rubbers for dichroic beamsplitter give too much stress, since my collimated Gaussian beam turns to elliptical beam horizontally after about 50 cm. I tried my dichroic beamsplitter as well as a standard beamsplitter of Thorlabs (BSW20). My Nikon filter cube has no such problem (as you may know, it has a metal spring, instead of rubbers).

Poster: jlow

Posted Date: 2013-05-14 11:56:00.0

Response from Jeremy at Thorlabs: It could be that the screws are being over-tightened. You just need to have the screws in finger-tight (just enough to hold the optic in place). Also, it would be good to screw in both screws a considerable amount before the final tightening. I will contact you to discuss about this further.

Poster: n-lindquist

Posted Date: 2013-05-04 13:45:03.383

I am using a 1.1 mm thick "laser flat" dichroic filter and noticed that some significant astigmatism is introduced when mounted in this DFMT1 cube vs your standard cage-cube dichroic filter holders. Could the DFMT1 bend the dichroic at all?

Poster: jlow

Posted Date: 2013-05-09 16:43:00.0

Response from Jeremy at Thorlabs: The DFM shouldn't be bending your optic. I will contact you directly to look into this issue you are having.

Poster: werley

Posted Date: 2013-02-20 14:54:22.65

The magnetic filter cube is very convenient and we are hoping to use it in several home-built microscopes in the lab, but there are a couple issues. First, it would be great if the cube could accept slightly larger dichroics (26x38mm) that are standard in some Olympus filter cubes. This would facilitate interchange between different microscopes. We are hesitant to make the switch if we can't use any of the dichroics we already own. Second, I don't like how the piece that unscrews from the DFMT1 to insert or remove the dichroic has a smaller clear aperture than standard for SM1. Could you not move the rubber cylinders so the press on the corners of the dichroic to fix it in place, and bore the holes out a bit further? Thanks.

Poster: cdaly

Posted Date: 2013-03-06 09:09:00.0

Response from Chris at Thorlabs: Thank you for using our web feed back. The DFM had been designed with the intention of keeping the product as compact as possible for use with our dichroic filters for fluorescence. I agree that this interoperability would be quite useful. I will bring up your recommendations in our internal forums and make sure that this is known to our engineers for possible revision.

Poster: tcohen

Posted Date: 2012-12-06 16:26:00.0

Response from Tim at Thorlabs: Thank you for your feedback! The DFM is designed to accept our line of fluorescence dichroics and our standard dichroic mirrors. For larger filters, we offer a solution with the use of either the CM1-DCH or the C4W with a B3C and FFM1. These have recently been updated to reduce deformation of the filter.

Poster: seamus.holden

Posted Date: 2012-11-27 13:39:45.043

I would very much like to use thicker dichroics (2mm) with this design. Thicker dichroics are very important for TIRF applications. Has there been any progress on this? - I see that this issue was last raised in March.

Poster: bdada

Posted Date: 2012-04-23 16:48:00.0

Response from Buki at Thorlabs: Thank you for your feedback. We are discussing your request with our production team and will post an update soon.

Poster:

Posted Date: 2012-04-19 14:52:21.0

Limiting the dichroic thickness to only 1 mm really limits what filters you can use. Can the design be modified to support thicker filters?

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30 mm Cage-Compatible Fluorescence Filter Cube

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