This is description of this part:
Swing-out arm for the top lens of the Olympus BH2-SC microscope condensers, and also for the U-SC and its variants.
The achromatic BH2-SC / U-SC microscope condensers have an upper, swing-out lens. When it is in the light path, the condenser offers N.A. 0.9. With the top lens swung out, the condenser works at a low numerical aperture of N.A. 0.16 (values from 0.16 to 0.2 are quoted on the internet). It is exactly this arm that does the swinging, and it is what I offer here: it holds the top lens in its mount above the condenser body and at the same time lets you swing it out of the light path.
In the BH2-SC / U-SC condensers this arm with its mount is a single casting together with the lever the user grips. The whole part is fastened to the condenser housing with a single screw (included). The lens sits in the mount without a thread and is clamped by three screws - you can see it and read its description here: https://www.microscopeparts.eu/part/99924.
The inner diameter of the mount is 23 mm.
Please note: originally there was a rubber sleeve on the small lever, which you grip with your fingers, so that the grip is firmer and the fingers do not slip. It is missing here - it must have been lost somewhere during use. It is a removable, replaceable item. If you have a damaged arm in an old condenser and you are looking for a replacement - do not throw away your old rubber, you can move it over without any trouble.
The working position of the whole arm with the top lens is set by a pair of stops - the small screw on the arm rests against the screw in the body. Thanks to this the lens locks in the same place every time it comes back and does not have to be centred again each time.
This particular part was removed from an Olympus BH2-SC condenser taken out of an Olympus BH-2 BHS microscope.
I could not confirm this, but everything indicates that this arm will also fit the microscope condensers for Olympus BX microscopes:
- Olympus U-SC
- Olympus U-SC-2
- Olympus U-SC3
The microscope condensers listed above are sometimes referred to collectively as:
- Olympus Achromat 0.9 flip-out condenser
- Olympus 0.9 swing-out condenser
Before you decide to use this arm in a condenser other than the one it was removed from - compare its appearance and dimensions carefully.
What goes wrong in this mechanism? Here is an example list of problems that can be solved by replacing the arm:
- the arm wobbles on its axis when the pivot screw is loose or worn
- the lens stops returning to its place when the stop screw has been unscrewed or lost, for example during cleaning
- the lens mount gets damaged when someone tries to force the lens out without undoing the three screws
- the casting cracks when the condenser is dropped - the arm sticks out beyond the outline and takes the impact first
This arm is not a spare part for a microscope. It is a part for repairing or rebuilding the condenser - and that condenser can sit in various microscopes.
When replacing the arm with another one, bear in mind that the stop for the working position sits on the arm itself. A new arm will most probably have to be readjusted with that one screw until the lens sets itself exactly on the axis of the light path.
When the arm is swung out, there is no optics left above the iris diaphragm - only the protective glass cemented into the body remains (https://www.microscopeparts.eu/part/99926). It is what then protects the diaphragm blades (https://www.microscopeparts.eu/part/99927) from dirt falling from the stage.
Here are examples of microscope models in which the condensers that this arm fits are most often used:
- Olympus BH-2: BHS / BHT / BHTU
- Olympus BX: BX40 / BX50 / BX51 / BX60
The most important microscopes used with the condenser models mentioned here are listed in the "compatibility" section, but this is by no means a complete list.
The last photos show the microscope condenser that the arm offered here comes from - and a blue arrow points to the part I am talking about.
A curiosity: it is possible that this part also fits the Meiji MA976 microscope condenser.
What is this part needed for?
- if you have an Olympus BH2-SC / U-SC microscope condenser with the arm holding the top lens missing
- if you have an Olympus BH2-SC / U-SC microscope condenser in which the arm holding the top lens is damaged
