The Eclipse E200, Labophot and Labophot 2 have built-in 20 W halogen lamp houses. These lamp houses are quite often broken on used Labophot 2 microscopes, but rarely on the original. Some versions of The labophot included no provision for diascopic illumination - there was no bottom light and the condenser stage, if present at all has no rack and pinion, which I assume is the way it shipped from the factory.
For episcopic illumination, the standard is the 50 W halogen lamp. This is essentially the same lamp house that is standard with the Diaphot diascopic illumination.
One of the key differences between the Labophot and Optiphot series is that the Labophot series uses 20 W lamps at the bottom, the Optiphot has a 50 W, and the Optiphot 2 has a whopping 100 W halogen bulb!
An attractive option for high intensity illumination for both brightfield / darkfield episcopic illumnination as well as a source for epi-fluorescence is the Xenon arc lamp, available at 75 and 150 W. They are better for regular epi work than mercury lamps because they have a favorable spectrum.
For serious ultraviolet excitation fluorescence microscopy, the source of choice is the mercury arc lamp.
Modern systems, even including epi-fluorescence, are now sometimes powered by LED illumination. Aftermarket retrofit LED lamps are available to give new life to an old microscope or indeed to add the second light source to a system with only one. Shown below is a Labophot that did not come with diascopic illumination, but I retrofitted a 15 W LED into the base. Adding a collector lens improves brightness and keeps annoying stray light from the microscopist.
There are situations where light internally supplied by the microscope, either from the top or bottom, is not the ideal source. External lamps, ideally through a gooseneck for ease of positioning, can provide the best illumination for your subject.
There are systems where a lamp is housed in an enclosure and fed to the desired location via a fiber optic bundle, called a fiber light. These can be incandenscent, halogen, or arc lamps. Certain episcopic illuminators have a port to accept a fiber light.
It is fairly easy to replace the lamp in the Dolan-Jenner Model 190 Fiber-Light. They take bulbs (model EJA from replacementlightbulbs.com) for the high-intensity version or model EKE for the longer-life lower output version, which are 21 V 150 W bulbs with a parabolic reflector integrated. These are the Osram brand high-intensity verison. Simply remove the four indicated screws on the top (after disconnecting power!)
As seen above, the lamp is held into the fixture with a spring clip. Carefully remove the hooked end with pliers an then disconnect the bulb. Wear gloves when handling (at least) the new bulb!
Electrically, it appears to be a simple four position potentiometer (Off, Low, Medium, High) and a transformer. You may notice the light / heat induced damage to the black anodizing around the input to the fiber - that is a pretty serious lamp!
There are also more modern systems where elecrical current flows through the gooseneck to LEDs at the end.
for navigation!