Since the Fall of 2010, the Microscope Tube Adapter ProScope Microscope Tube Adapter, order code BD-MTA, $119 has shipped with a mounted reflective IR cutoff filter. This filter eliminates the issue presented in this TIL. If you have an older adapter without the filter, you might considering purchasing the newer model.
For owners of microscope tube adapters purchased before this silent change, two basic options exist for dealing with issues of brightness.
First would be to obtain the appropriate Reflective IR Cutoff Filter from a reputable supplier (Bodelin, Sunex, etc.)and mount it into the tube adapter.
The second would involve the following make-shift method of overcoming the problem of too much brightness.
If your microscope has an adjustable diaphragm, change it to reduce the amount of light passing up through slide specimen.
For scopes that control light by turning a sub-stage disk with holes of varying diameter, too much light may still flood through. Try the following:
1. Turn the sub-stage disk to a position that is part way between two settings to reduce the amount of light.
2. Take an 8 cm by 8 cm piece of aluminum foil and cut a small 1 mm by 1 mm hole in the center of it. Place the piece of foil over the lamp with the hole in the middle of the lamp. For higher magnifications, larger diameter holes of the sub-stage disk will need to be used.
3. Change the lamp bulb to a lower wattage. Bulbs for these scopes generally range from 10 to 30 watts.
4. Plug microscope into a power control and use the controller to dim the light level.