Flourescence microscopy equipment

Changing the Zeiss 47 17 61 flourescence epi-illuminator condensor on the Zeiss IM microscope

When I purchased my Zeiss IM inverted microscopy just over one year ago, there was no epi-fluorescence condenser present. I purchased one off ebay (Zeiss part 47 17 61 – in this post I will call it the EFC). Unfortunately, the filter slider was stuck. Luckily another in full working condition came up very cheaply recently and I have now replaced the first one. However, the technique for taking one out and putting in another was not obvious so this post is to record the process for future reference, should I or anyone else want to make this change on the Zeiss IM or IM35 microscope (both use same component). I will probably wish to do this myself. After I find a way to fix the stuff filter slider, I also have a Zeiss IM35 and will probably put the spare one on that, although epi-fluorescence requires use of the fluorescence cube for the microscope and I only have one of those and they are quite expensive second hand, so I doubt I will be acquiring a second one soon!

It is worth noting that the EFC provides epi-illumination but was only designed to be used for fluorescence microscopy. I am hoping to adapt the fluorescence filter cube to remove one of the filters and replace with plain glass so that I can use it for more general epi-illumination. Today’s project was the first step in this process as it allowed me to slide out of the way a blue filter in the filter slider which was stuck in the light path. In fact this needed to be done prior to the removal of the old EFC and – given that the reason for Today’s project is that it was stuck – this required the use of a hammer to be achieved! I was gentle and put something between hammer and microscope with softening covering (spare piece metal coveted in kitchen absorbent roll) and managed to succeed without causing further damage, although my heart was in my mouth while I did it.


Zeiss 47 17 61 epi-flourescence condenser  (EFC). This is the one that I removed today. You will notice that there is one slight difference between this one and the new one I installed in its place, which is shown in the later photos on this post – the adjustment screws for centering the illuminator light are longer in the new version. These can be seen in the later views from the back of the microscope.

Back of microscope – epi-illuminator is central round bit. The illuminator will be attached here (not attached in this photo):

The following pictures show an illuminator attached to the back of the Zeiss IM35 microscope. It is the square box hanging off the back, opposite the eyepieces (oculars). It would be exactly the same with the IM microscope as the only difference between the two varieties of microscope is that the IM35 has an inbuilt camera port whereas the IM does not have one.

View of epi-fluorescence condenser (EFC) from next to the eyepiece turret. This view shows the filter slider within the epi-fluorescence condenser component that was stuck on the first one I installed on the microscope. The epi-fluorescence condenser comprises both the white and black round parts on left side of the picture. The black part is seen to contain a circular filter holder with small black handle. This can be removed. For installation of the whole component or taking it out again, both the filter slider and the round filter holder need to be removed. This allows the whole component to then be slid out through the hole in the casing on the left – that hole is currently obscured by the black circular component which sits over it.

The the following photo shows the EFC from the other side. The long thin silver metal handle controls the aperture control within the EFC. To install or remove the EFC from the microscope, this handle must be first removed so that the EFC can slide out through the hole, otherwise it will obstruct it. The handle is removed by twisting it anti-clockwise, which will unscrew it from the EFC.


1. Start at back of microscope.

2. Locate the four retaining screws on the back which hold the etc In place and remove them.

3. Unscrew and remove long thin handle.

4. Locate and remove tiny screw from end of filter slider. This screw prevents filter slider being removed from EFC. Once screw is remembered bed, slide filter slider completely out of the EFC.

5. Remove content recluse filter holder (left below) from EFC. Note in this picture, filter slider is also shown as present but of course by now you will have already removed that in previous steps.


6. By now the EFC should be quite loose. Note it only pushed again eyepiece turret and not attached to it so there are no screws etc that need to be loosened there. The EFC should now be easy to thread through the hole in the back of the microscope and removed.

7. Insert new EFC by reversing the above.

Illuminator for epi-illumination during fluorescence microscopy with Zeiss IM/IM35 microscope

This is the illuminator I have obtained which fits on the epi-illumination port at the back of the microscope: Zeiss part 46 72 59 – 9901. This is the illuminator which is meant to be used with a mercury lamp for fluorescence microscopy.

It is quite a heavy bit of kit and like everything that fits on these microscopes made of metal and built like a tank!

The following link opens a manual which seems to work for this illuminator, although I am not sure whether it is exactly the right one:

Zeiss Illuminator 100 user manual (PDF file)


The next picture shows a small Allen head screw in the central depression on the bottom of the illuminator. Loosening this (does not need to be completely removed) allows the lamp and its base to be slipped easily out of the housing for examination +/- replacement:

The next pictures are of the lamp that is in the illuminator – this came with it when I purchased it from ebay:


I think this is a new version of the lamp above:

100W appears to be the correct rating for this illuminator as noted on the underside of the lamp base:


Fluorescence cubes for Zeiss IM and IM35 microscopes

I have added some posts re fluorescence microscopic images with my Zeiss IM microscope. This is very much early days but has been made possible by the purchase of a second hand (everything to do with this microscope is of necessity second hand as it is somewhat antique) fluorescence slider with two cubes on it – Zeiss item 46 63 01 – 9901.

I am not sure what the filters are that are on it but I have seen an advert for another IM microscope being sold with similar slider and there the filters are listed as:

Including 50w HBO (mercury) illuminator and 2 complete filter cubes that appear to be in excellent condition:

Cube#1: FITC. Excitation: 450-490nm. Dichroic Mirror: FT 510nm. Emission Spectra: Long Pass LP 520.

Cube#2: UV. Excitation: Band Pass 365nm. Dichroic Mirror: FT 395nm. Emission Spectra: Long Pass LP 397.

So perhaps my filters are the same – one thing I do need to do is check my epi-illuminator does not have mercury bulb in it – rather dangerous! Actually, if it does now then this raises a big question about how I can illuminate any fluorescent dyes or where I can get any fluorescent dyes from in the first place……but those are questions for another day!

The filters are somewhat loose in the cubes – so that is also something I need to sort out. I think the glue has gone loose. Considering that such filters are many hundreds pounds each, I am somewhat relunctant to try gluing them as I am concerned the glue will ruin them – I wonder if I can find some appropriately sized rubber/plastic washers.


Possible washers for fluorescence cubes: