Tips on extending bulb life
Bulbs have a rough life in a microscope: burning in an enclosed area for hours on end with a finite lifetime, the effects of too much heat and not enough ventilation, DC current from the dimmer circuit slowly thinning the metal of the filament. And with bulbs nowadays being manufactured more and more cheaply, the cumulative effect is not good for bulb longevity.
If the bulb is halogen or DC Arc Lamp type, DO NOT TOUCH THE GLASS with your bare hands when installing bulbs. Use the plastic bag it comes in to install the bulb. DO NOT jar or bump or run your scope in an environment that has excessive vibration. Turn your scope off if you do not need it on. Some bulbs have a rated life of only 100 - 200 hours so if you use your scope full time, be prepared to use bulbs.
Halogen bulbs in microscopes and fiber optic light sources can also have problems if the socket is worn out; i.e. the connection cannot sink enough heat away from the bulb and/or the electrical connection is weak. If your scope is an old workhorse who's starting to eat bulbs, check the bulb socket out for poor contact and discoloration of the contact. The bi-pin type bulb should push stiffly into the socket. If not, or if it wobbles around excessively, the socket is too old and needs replacement.
