What are the common types of microscope light sources?

Some common types of microscope light sources are incandescent lamps, Arc lamps, halogen bulbs, and LEDs. Incandescent lamps are composed of glass, an inert gas, and a filament that transforms a direct current to light. These lamps provide a steady source of illumination and are the most common type of bulb used in optical microscopes. They are cost efficient and found in many shapes and sizes. Halogen bulbs use quartz to protect its glass against high temperatures and bromine gas. Bromine absorbs the tungsten, resulting in a bulb that functions at a lower wattage and lasts longer than an incandescent lamp. Arc lamps are light sources that create an electric arc between two electrodes. These lamps use mercury or xenon ions to create white light at a high intensity for use in fluorescence microscopes. Arc lamps are sensitive to outside factors like an unstable power supply or nearby electromagnetic field. LEDs are used commonly in widefield fluorescence microscopy. They require little power to function, have long lifetimes, and create energy into light without making excess heat. LEDs emit a narrow wavelength range and can run days at a time without burning. The cons are that they emit a bright white or blue light that can alter the appearance of some samples.