My illuminator had an "EJA" bulb, which eventually burned out. I found that replacements cost about $10 online. An EKE bulb is a virtually identical replacement and can be found for lower prices. Both the EJA and EKE are 21 volt, 150 watt bulbs with a GX5.3 base, so they will clearly fit into the same socket and work (and I know a fellow with the same illuminator as mine who uses EKE bulbs). The difference is specified light output, color temperature, and service life.

• EJA - 354 lumens, 3400K, 40 hours
• EKE - 80 lumens, 3300K, 200 hours

I bought my EJA bulbs from 1000Bulbs.com

These are all quartz halogen bulbs (the halogen is typically bromine). They emit about 80 percent of their energy as infrared, which is passed by the reflector (rather than being reflected), so most of this ends up as heat in the enclosure. The remaining 20 percent is visible light, which is mixed with the small portion of infrared that is directly emitted by the bulb. Using a fiber eliminates this small amount of infrared, thus avoiding cooked samples and melted plastic boxes and such.