top of page

LED Longwave (LW - 365nm) Lighting for Home Displays

Longwave Fluorescent Display Cabinet

By now the fluorescent mineral community has heard of the new Convoy S2 365nm flashlight that has taken our hobby by storm. It is the most significant new technology to hit our hobby in years, or even decades. Based on a high power 365nm UV LED, it is providing field collectors with an intense, cost-effective light which amazes anyone who tries it.

Problem is – it’s a spotlight. When used with a filter it generates an intense, narrow beam of pure 365nm UV. Perfect for lighting up minerals in the field, at shows, even in the daytime. But it’s pretty much useless for a home display. The narrow spot lights up an area about 2 inches in diameter when held 5” away. Held 2 feet away it lights an area of about 10 inches – hardly practical for lighting up a three foot wide, four foot high display cabinet.

For home displays the current state of the art (before now) is to use inexpensive black lights (crappy BLB’s) or very expensive longwave luminaires (up to $1k). Neither offer the intensity of the Convoy flashlight and both have drawbacks.

Enter the Ultra-365 distributed lighting system – for a couple of years now I have tried to talk lighting manufacturers into developing a LW LED light for home displays, with no success. LEDs are complex animals, totally different from the fluorescent lights manufactured for the hobby today. I guess the required skill set to develop a new product simply isn’t there, or perhaps they don’t see the need. So I reluctantly sat down and built my own. This Glow Note will describe my lighting system and its benefits. Perhaps eventually some manufacturer will be motivated to design/build their own.

The display photo is of my home display lit by one of these systems (daughter for scale). It was taken in the middle of the day with average ambient lighting, and measures about 3'x3', 3' deep. Activated by a motion detector, the lights come on automatically whenever someone walks by – always capturing attention, a little shock and awe, and plenty of comments. But it’s much easier to illustrate how LEDs work and their effectiveness in lighting using a simple “light board” which depicts fluorescence intensity and beam patterns rather than a complex display of rocks with varying fluorescent responses.

Longwave Display "heating" a room

One person installed this LW lighting system in an unused fireplace - novel idea!


For this discussion I set up a white poster board (3’ x 2’) which is very fluorescent. Various lights were installed to illuminate the board and I used a camera as a “poor man’s” light meter to depict the intensity and patterns of the light.

LW 365nm Light Comparison

Figure 1 – these three photos were taken with the exact same camera exposure settings. Only the source of the UV light was changed. (a) is the Convoy, (b) is the common black light (BLB), and (c) is my Ultra-365 Distributed Lighting System.

Fig. 1(a) shows the Convoy flashlight illuminating this 3 foot high, 2 foot wide poster display board. This board is very fluorescent and illustrates the intensity of the 365nm UV beam – focused into a small, intense white spot. Fig 1(b) shows the same poster board illuminated by two black lights (20 watts on top, 13 watts at the bottom). The poster board is illuminated evenly but dimly (this was the base setting for the camera exposure). Fig. 1(c) shows the poster board illuminated by my Ultra-365 Distributed Lighting System. Five high-power LED lights are distributed around the edges in a floodlight configuration bathing the entire area in intense UVA. In all cases, the whiter the exposure, the brighter the UV.

The Convoy flashlight – Fig. 1(a) - generates an intense beam of UV. This is accomplished using two methods: a high-power, pinpoint, pure UV LED light source, and a tightly focused reflector. The result is an intense spot of light which will almost make coal glow. The two black lights (one top, one bottom) - Fig 1(b) - are standard fluorescent bulbs (Phillips 20W and 13W). At first glance one might think they put out a nice even light but keep in mind that this is a very fluorescent piece of white paper (poster board) being used to indicate UV intensity. In reality the UV output of the two bulbs is rather low, as indicated by the lack of white exposed areas.

Fig 1(c) shows my distributed LED system. Similar to the Convoy, high-power LEDs (each ~2.5 times the power of the one used in the Convoy) are mounted as flood lights (not spot) around the edges of the display. The entire display area is bathed with intense 365nm UV, LEDs aimed in any direction, depending on the layout.

The basic components of this system consist of a master “down light” and up to four satellite “accent lights” (Fig 2). The master supports up to four high-power LEDs itself (two shown here – each LED is appx. 4 watts) while each satellite light has one 4W LED. The master light is powered by a single power supply and can power up to four satellite lights.

The entire system (Fig. 3) is controlled by a motion detector which activates the lights whenever there is movement in the room. Even in daylight, the resulting fluorescence is quite stunning. At night time the colors light up a dark room with intensity not even achievable with fluorescent lighting luminaries costing nearly $1,000.

Figure 2 – the basic lighting components

Ultra-365 Lighting System Components

Figure 3 – a complete Ultra-365 Distributed Lighting System showing the master light with three satellite lights, power supply, motion detector, and power cable.

Satellite Light Mounting

Each lighting component can be installed various ways. The master light can be hung using wire hangers, or installed in a cutout in the display. The satellite lights have mounting brackets which can be angled in any direction for precise illumination depending on display requirements (Fig. 4), mounted either to the top of a cabinet or the sides (or even set in a small round cutout in the top). Extension power cables allow the lights to be distributed around any size cabinet (Fig. 5).

Oversized heatsinks insure long life for the LEDs. Heat is the enemy of UV LEDs, much more so than white light LEDs. These lights barely get warm, insuring lifetimes of 20,000 to 50,000 hours.

Figure 4 – Satellite LED mounting

Power Distribution/Cabling

Fig 5 – Power Distribution

Unlike fluorescent lighting, there is no warm up time (fluorescent bulbs can take 5 minutes to achieve full brightness when cold). And, LED lights can be rapidly cycled on/off with no effect; the life of fluorescent bulbs is dramatically affected by power cycling – really not advisable to activated using motion technology (unless you want to change the bulbs every month).

UV Beam Projection

Beam Projection (Fig. 6) – the intense power of an LED is a result of the pinpoint UV light source, all focused out the front of the light. A fluorescent bulb radiates UV 360 degrees with much of it lost to the back of the bulb (even with properly designed reflectors). There is simply no comparison when it comes to intensity. But a fluorescent bulb does provide an even flood of illumination over a wide area. The distributed lighting system here allow us to flood our displays with intense 365nm UV, focused directly on areas where it’s needed – up close and personal (everyone knows the closer your light is to a rock, the brighter the rock). The beam out of the lights is radiated at a 90 degree spread. The arrows in Fig.5 show this spread for each individual light as I positioned them. The lights are not directed towards the back of the display but at angles illuminating the rocks on the “shelves” (that are supposed to be there). Like the Convoy S2 torch, the UV beam is intense. But unlike the Convoy which has a 15 to 20 degree focused spot beam, these lights have flood beam of 90 to 100 degrees. Although the poster board used to show this intensity is only 2’ X 3’, the LW section of my home display (illuminated by this system) is 3’ X 3’ and 2’ deep (Fig. 1 above). These lights provide plenty of UV to light up even the largest of displays. Museums might install multiple lighting systems for very large displays. Up to 3 Ultra-365 systems can be powered by a single power supply and motion detector.

Fig. 6 - UV Beam Projection Angles

Fig. 7 - Animation showing each LED light's beam - completely customizable to each display

Filters and Power – ZWB2 filter glass, used in these lights, has proven to be even more effective than Hoya or Wood’s Glass commonly used in LW fluorescent lights. The transmission graphs (and actual testing) shows that ZWB2 glass allows much less “blue bleed” to pass and only pure UV. LEDs are far superior to fluorescent LW bulbs when it comes to visible light leakage. On top of that, LEDs generate a very pure 365nm peak with only minor overlap beyond the 400nm (visible) light range. The ZWB2 filter blocks this small amount of visible light entirely. All light directed to the rocks is UV with a sharp peak at 365nm.

But, as they say, the proof is in the pudding. LEDs are so superior to fluorescent lighting it’s almost a sin to display rocks under the archaic fluorescent bulb technology. True 365nm high-power LEDs will reveal fluorescence in minerals not even thought to be fluorescent. And the washed out color from blacklights and inferior fluorescent LW bulbs and filters are a thing of the past. How better to illustrate then by pictures of an actual specimen?

Fluorite and Calcite - Morocco

Fluorite and calcite specimens from Morocco can be some of the most beautiful display pieces in your LW collection. But rarely will you find them displayed – they just don’t look great under LW fluorescent lighting. The piece shown here is one of my favorite rocks. Beautiful greenish fluorite crystals are distributed on a druzy calcite matrix, with lots of pyrite thrown in for the white light enthusiasts.

I took three UV pictures of this specimen. The first (photo 1) was of the piece illuminated by a 20 watt Phillips blacklight about 4” away; the camera was set to take the best photo possible with this light. The second (photo 2) was taken with the same exposure settings as the first and same distance from the light, but illuminated by a single Ultra-365 4W satellite LED; this picture was overexposed due to the brightness of the LED but using the same camera settings as used for the blacklight. The third (photo 3) is correctly exposed, taken using the LED and the proper camera exposure settings for the intensity of the LED. The fourth image (photo 4) is an animation showing the dramatic difference in fluorescent response between the blacklight and LED.

While this may seem shocking, it’s really not an exception. Most folks are floored by the intense fluorescence excited by properly designed, powerful LED lights. Blacklights are simply no match for LEDs. Fluorescent lights (BL bulbs) with Wood’s filters are only slightly better. The intense UV beam and purity makes rocks do things not seen before. Convoy users are well aware of this phenomenon.

Photo 1 - fluorescence under 20 watt blacklight

Photo 2 - Fluorescence under 4 watt Ultra-365 LED (same camera settings as photo 1)

Photo 3 - Proper camera settings for Ultra-365 LED lighting

Photo 4 - Animation showing the dramatic difference between as blacklight and one of these LEDs

How many lights? A lot of questions have been asked about the number of lights for a given display. One person sent me a pic of his display and I added some beam projections showing what I would recommend. This applies to any LED installation. LEDs are quite different from fluorescent lamps. The beam is very directional (thus the brightness). The Ultra-365 lights are designed as floodlights but they still only have a 90 degree spread. The Master, mounted on the top, has two LEDs (or four if desired for serious intensity) and acts as the main floodlight illuminating most of the display cabinet. But the directional beam still leaves some corners "in the dark" - mostly at the upper levels of the display. Adding two Satellite lights on the sides, aimed properly, will catch the upper corners as well as significantly add to the main area of lighting. The result will be a very well lit display cabinet. Of course one could probably get away with a single Satellite if you arrange the rocks accordingly (or even none). But I like really bright displays and this configuration will result in the brightest.I tried to describe this in pics showing the beam paths on a typical cabinet. The arrows indicate the light from the Satellites, while the main beam is in UV purple.

Mounting lights for best results

Summary – As Convoy users know, there simply is nothing better for a LW field light. It outperforms field lights costing $400/$500 at a fraction of the cost. But it is not a solution to a home display cabinet. The focused beam only lights a small area. The Ultra-365 provides an intense 365nm in a floodlight configuration, allowing large displays to be illuminated at a fraction of the cost of high-end $1k fluorescent lamps/luminaires, and with a purity of color and intensity that cheap blacklights simply cannot replicate. Based on LED technology, these lights will last for many years, can be powered on/off an unlimited number of times, and are very price competitive.

I’ve built a handful of these lighting systems in one form or another for friends over the past couple of years. I’ve given up trying to convince the lighting manufacturers active in our hobby to build lights based on LEDs. I have purchased enough parts to build approximately 20 to 30 of these lighting systems at a reasonable cost. Once they are gone I may build more, or maybe someone will finally “see the light” and manufacture the next generation LW lights for our hobby. Want one today? Limited manufacturing here:

2,587 views0 comments
bottom of page