Transilluminators - Overview

A "transilluminator" typically has 15W MW bulbs installed (312/302nm). Some have 6 bulbs, some have 4. So far, almost every unit I have come across has Hoya U325c glass (SW glass). Since they have been run using MW bulbs the filters are not solarized and perfectly suited for our application. Various units have various filter sizes – 8" x 16", 8" x 8". The larger filter the better of course. My favorites are those with large filter areas - 8" x 16". CAUTION: there are some trannies which are LW and have LW filter glass (Wood's Glass) - check the model# and google it if not sure, or ask on the Facebook Fluorescent Mineral Group. SW filter glass is smooth while the LW glass has a rippled surface.

A transilluminator to light fluorescent minreals

Instructions to upgrade your own are here...

For the most part I have found these units to be scuffed, rusted, abused, etc – but the glass is usually pristine and the ballasts work. Sometimes the glass can be scratched from scientists cutting their gels directly on the glass, but aside from cosmetics these seem to work just fine.

It's a simple job to replace the MW bulbs with SW bulbs (ozone free) and you have a 60w/90w SW display lamp with a 8" x 16" filter – huge and bright. With electronic know-how you can replace the ballasts and install new connectors, new ballasts, and 4ea 60w "U" tubes for a 240w monster light. Or, you can simply replace the magnetic ballasts with electronic ballasts and drive 25W bulbs for a 150w lamp. Some seem to have various types of reflectors – I usually replace them with specular aluminum if they are not already – not sure if that matters a whole lot as the company who designed the unit probably selected their reflector material for optimum UV output – I just don't like the white reflectors.

I'm always on the lookout for deals. On Ebay I try to buy them for under $250 plus shipping. I use these at shows, and for my personal display. Sometimes I buy them just for the glass – vastly cheaper than buying new glass. Manufacturers (units I have bought) include:

  • Fisher Scientific

  • Ultra-Lum

  • Fisher Biotek

  • Fotodyne


a fotodyne light

This is a small filter area Fotodyne unit. I wouldn't pay more than $125 for it. It can be upgraded but will require smaller bulbs and ballasts.

UV fluorescent mineral light


This is a Fisher Scientific unit. The filter area is only 8"x8" - much smaller than the larger units. The bulbs and ballasts are the same as the larger units, just a lot of the light is blocked by the cover.

UV Fluorescent Mineral Light

A UVP unit - same story as the Fisher above.

UV Fluorescent mineral light

This is the "gold standard" - a Fotodyne 3000.

Filter area = 8" x 16". Note that there is a plastic cover over the filter area held on by screws in the corners and a plastic hinged lid. This cover protects the filter while the scientists cut their gels with scalpels. The result is a pristine, like new, very large filter. They come with either 4 or 6 bulbs - 6 is better! I've even used units that had scratched filter glass. Doesn't look good cosmetically but works fine (as long as the filter isn't scratched so bad it's opaque). Again - be sure that the unit you purchase is a midwave model (typically 312nm). It really doesn't matter if the bulbs are good as you will replace them. For me, I don't care about the physical appearance (rust, etc) as I usually paint the entire unit flat black. On some the Hoya glass might be scratched. I have purchased only one unit which had SW bulbs in it, and was completely solarized - but that's one out of perhaps a dozen (and it still works - just not as bright as others).

UV light with white light LEDs installed

Need some white light? Install LEDs around the edges



Leave a comment

Please note: comments must be approved before they are published.

.ezsd-arrows .ezsd-arrows_arrow { position: relative !important; padding: 0; height: 100%; pointer-events: all; opacity: 0.9; background-color: white !important; }