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UV SAFETY] UV-C Light Is Dangerous NEVER look at a UV-C light. NEVER let UV-C light hit your skin or eyes directly or by reflection. UV-C light can cause: severe burns of the eyes and the skin, and DNA damage from broken chromosomes. When working with UV-C illumination, you MUST: cover up completely, wear head & eye protection, and have strong ventilation. Hello there. It's been a long time since I posted. Life got in the way. But this video just came in and it is honestly a little bit concerning. Brainiac75 tests the output of halogen lamps and finds out they emit a small amount of UVC. I have an unfiltered 125w spotlight that I have used a few times as a lightsource and I am wondering what the implications of this are. So I was browsing AliExpress for fun last night, and I ran into this. https://www.aliexpress.com/item/4000805185239.html?spm=a2g0s.8937460.0.0.2f5b2e0eAat3SH It's extremely cheap and if you would have shown me this and asked me what it is, I would say it looks like an incandescent lightbulb judging off of the looks. But it's not? I have no idea what this could be, is it simply filled with mercury vapor and there's a current jumping between the two electrodes? Also they sell a "With Ozone" and "No Ozone" versions which confuses me further. I wont buy it since I don't own any UVC safety gear, but I'm still curious.

Might be a bit of a boring post, I wanted to confirm that my 940nm eBay flashlight is in fact, 940nm, so I just laid two glasses on a pile of books, one filled with water and one empty, I put on my 950nm longpass GREEN.L filter and I illuminated the scene with said flashlight. The water filled glass appears significantly darker, almost tea-like, so I assume that confirms I got what I wanted. Today I ordered another two flashlights. https://www.ebay.com/itm/233636435366?var=533326117053 https://www.ebay.com/itm/392804813218 One of them is just plain red, so it's probably 630nm-ish. Hopefully that won't be too much of an issue, I suspect it could bring extra color and saturation to any trichromes I make with this. I also ordered this. https://www.ebay.com/itm/133238203848 Just a single bandpass filter, I'll test it out once it arrives, and if it's good (doesn't decrease sharpness, doesn't leak too much of other wavelengths), I will buy a few other ones. As I said, I'll probably putty mount them on my Industar 50-2 right up to the front element.

Awhile ago I found that it was possible to remove visible light contamination in UVIVF photography by subtracting an (averaged) image without the torch from an image illuminated with the torch. This method was used to excellent effect with the Queen Anne's Lace that I showed some time ago. The secret is to only subtract on 16 bit linear images, which can be obtained from PhotoNinja by turning off everything except the white balance. Do not try image subtraction on JPEGs! You won't get nice results. The filters used were BG38 2mm + Tiffen Haze 2E, and the contaminating background light is streetlights. The white balance and color correction were taken from the profile I made for the gourd photos the other day. The torch was the Nemo. Procedure was to take 30 photos with the torch off using the built-in intervalometer in my Son A7s, and then repeat the process with 30 more photos while light painting with the Nemo. I then took the median of the no-torch photos to get a combined no-torch image, and took the MAXIMUM of the light-painted images to get a combined with-torch image. Then I subtracted the streetlight-only image from the streetlights+UV image in Photoshop and adjusted contrast on the results. Final result: Image with torch + streetlights: Image with streetlights only:

Does anybody successfully use those cheap (~$20) UV LED flashlights with maybe 20 individual LEDs to throw a little extra light on flowers or insects when taking UV pics outdoors? Is this a reasonable way to get faster shutter speeds? I'm asking because I am finding it nearly impossible to do outdoor shots without long shutter speeds (~1 second, even with danger-level ISOs). Are LED UV lights potentially harmful to insects in the same way that the stronger (real) UV lights could be? Thanks.

I wonder if this one is true to specs ? https://www.amazon.com/Alonefire-Flashlight-Rechargeable-Ultraviolet-Blacklight/dp/B08RHTN7RV?ref_=ast_sto_dp

How do you set up a flash for UV photography ? I have been trying to learn flash photography, & getting some success with a normal visible light camera & auto lens with the flash set up for TTL. I am not having much success with manual flash on manual lenses ? Any help gladly received please. I am using a Godox AD200.

Very technical question, I hope it is appropriate to ask it here. I have a lot of projects in my to-do list, most of them will require a lot of money and it will likely take years before I can do them. One of this projects is a ~8-10 W 340 nm LED illuminator, to include it in my ~10 W LED collection. High power 340 nm LEDs are (oddly) all very similar, if not exactly the same. The one I already have is identical to this one: https://www.ebay.it/itm/202120730112 (the original listing is not there anymore). What I want is a PCB where I can solder four of those LEDs in a 2x2 square. Such PCBs are already available for smaller 3535 LEDs, such as my 265 nm LEDs. Example (there are many): http://kaidomain.com/20mm-x-1_5mm-Quad-DTP-Copper-PCB-for-4-x-Cree-XP-series-or-3535-LEDs-2pcs There are even bigger ones if you want: https://www.kiwilighting.com/5-channel-25led-spots-3535-pad-led-pcb-board-printed-circuit-board-for-cree-xpe-xte-xpg-xpl-xhp35-epileds-3535-led-beads but I didn't find a single one to hold four 6363 LEDs. I understand that four of them can not fit into a 20 mm star PCB, one of the most commonly used, but size doesn't really matter. What matters is that the LEDs are close together, as close as possible. If someone finds one or a way to obtain one, please tell me. Thanks.

Around noon today here in northern Nuevo Mexico at 6900 ft (2300 m), I was able to focus -- easily -- on some tiny flowers via Live View using the BaaderU on the UV-Nikkor 105/4.5 at aperture f/16 and ISO-100 (base ISO) with no boost for the D610 LCD screen and no extra UV light on the flowers. That's a lotta UV light, for sure !!! Live view focusing is usually not possible with the D610 + UV-Nikor + UV-pass filter unless a UV-LED is used on the subject while focusing and the aperture is set wide open to f/4.5. Exposure: f/11 for 1/8" @ ISO-100. This is SOOC, resized only. The flower is a Speedwell (Veronica) ground cover. The brighter flowers in the center are Vis white while the surrounding flowers are Vis blue. The white ones are slightly more UV-bright, so that is not a hot spot you are seeing there in the center. Here's one rendition of the UV photo. The foliage is quite UV-dark. For fun, I pushed the foliage saturation way up.

Basically, I'd love to see if some good soul out there on this forum compiled a few different light sources' emission spectra (example: Fluorescent blacklight, blacklight blue, maybe a few UV LEDs, normal and halogen incandescent, reptile bulbs etc etc) to see just how much UV and other you can get from each of them. I would gladly do it but I don't own nor do I have the finances to get a spectrometer. It could be very useful for everyone's experiments here, though. Don't go rushing to get your spectrometer though :), it's just a suggestion for if any extra dedicated members here ever feel like it.

WOW, spectrum of an uncovered Godox AD200 flash....

Experiments combining fill-in flash with natural UV Nikon-E 28mm, U-360 + S8612, modified Qpaq flash gun- max power + diffuser iso 400 f11 2 sec Lesser Celandine, Ranunculus ficaria, early morning with frost Weeping Prunus, snow showers

A week ago, Stefano PMed me, with the title, "MWIR camera at 'affordable' price?" I admit, I was skeptical, but the skepticism turned to amazement as I read the eBay listing. For sale was an Agema 470 Pro, at "Buy It Now" of $650, or best offer. The camera was of the HgCdTe (or MCT) type, which means it has a single pixel and a high speed rotating mirror that directs light onto the sensor, which is cooled via Peltier effect to -80C or so. Effective resolution was 100x140 pixels. The sensitivity is 2-5 microns, going from the long end of SWIR into the mid-MWIR. From 5-8 microns, air is absorbing, so no cameras are available in that range currently (nor likely ever to be). Beyond 8 microns is the usual LWIR window where my other thermal cameras work. The seller had posted pictures of the camera operating, and a power supply was easily available, so I thought: why not? So I got the camera. The camera is extremely large and heavy. It is about 50cm (22 inches) long, and it weights 7kg (15.4lb). It has a monochrome viewfinder and a floppy drive (3.5") for storage. I do not have any floppy disks alas. It took a few days to acquire a power supply and a light source. I bought a "Deep Heat Projector" from Arcadia Reptile. Arcadia had this to say when I asked about the spectrum last year in reference to my TriWave: I didn't buy it last year (didn't get around to it) but with the MWIR camera it was too handy to resist: better SWIR light and one that worked for the short end of the MWIR. So I got that along with a socket for it. Today all the stuff arrived and I put it together. The camera makes a revving up noise like a jet engine: a slowly building whirrrrrrRRRRRR!R!R!R!R!!!!!! as that mirror goes faster and faster. The electronics turns on and a boot-up screen appears, showing the software dates to May 1, 1989. The camera originally came with a variety of lenses, so the lens on the front is detachable. The one it came with was a 20 deg FOV lens — in IR, camera lenses are described by field of view (FOV) rather than focal length. With the lens removed, there is another (concave) lens behind it, and according to the ancient manual, which is available still from FLIR's website since FLIR bought Agema eons ago, you can use it in macro mode if you leave the outer lens off. Showing how highlights on my hand vanish when the reptile light is removed from my hand: https://youtube.com/Kz6nH_u0Teo Showing teeth changing temperature as I breathe: https://youtube.com/0exOl11PJSk

I have ordered a BeamZ fluorescent UV Lamp that takes 25W, my question is this: I can't exactly afford a Baader U-Venus-Filter (or other outrageously expensive alternatives with supreme IR supression), and the stack of filters I use right now unfortunately leaks some visible light (stacked ZWB1 and QB39), it works alright for the most part but the QB39 cuts off a lot of the UV and also there's the aforementioned leak. So I though of hacking it the other way around and obtaining a lightsource that only emits visible and UV so that a simple UV/IR dual bandpass filter would suffice. So, does a fluorescent UV lamp emit IR, and if so how much? I can effectively supress most visible light with my ZWB1 filter alone. I know that the quality of UV emitted by fluorescent lamps is nowhere near as uniform as the sun or converted flashes but it surely is better than LEDs, or am I wrong? I'd need to see for myself but the light sources I have ordered aren't here yet. I ultimatively aim to take UVA pictures of flowers and perhaps rocks or other interesting natural or even manmade objects. And if I can sucessfully obtain a pure UV lightsource, I will also use it for UVIVF. You don't need a wide spectrum of wavelengths for that though so I've been considering just mounting a UV/IR dual bandpass on a UV LED lightbulb.

Last autumn I presented an idea of supplying the Nemo torch from an external DC-source instead of a battery. https://www.ultravio...dpost__p__39017 The general idea was to generate the optimally low voltage for maximum output power with minimal heat losses. Later I decided to make this as a proper design effort instead of building a rats-nest. It was more complicated and expensive than I first expected, but a few months ago I had something working well. There were many iterations of the Cap-shell: I also had to buy a special thread-cutting tap matching the one on the Nemo's lamp-head and create a few assembly fixtures to make it possible to put all parts together properly. I designed a custom PCB and had to add an internal heatsink to keep the dcdc-converter from overheating. I have run them a few hours without any problem, except that they get hot to touch. The normal battery used with Nemo can not keep up the voltage above 3.8V for full optical power many tens of minutes. Here are some images showing the parts: These caps run on a dc voltage between 7V and 22V, with an optimum efficiency around 12V. The other voltages work well too. The lower voltage makes it possible to run the caps, off grid, with Bike light battery-magazines like these https://www.ebay.com...ED/162709619747 https://www.ebay.com...ht/124044447618 They can also run on any acdc adapter with suitable connector similar these 12V 2A versions: https://www.ebay.com...p/233918373015?

Sometimes I see things on Adorama and question my sanity. Or the sanity of whoever buys this stuff! Six 18W fluorescent black lights (366nm nominal wavelength) for the price of...well go look: https://www.adorama.com/krrb5003.html Do they pick these UV bulbs in the sacred garden of the goddess Boll Lux or something?

I purchased a uv torch from engenious designs and use the zwb2 filter. There is a dark spot in the centre of the light on the subjects. Is there any sort of diffusion material that would work to distribute the light from the uv torch onto the subject? Thanks

I have these blacklight bulbs, BlueX UV Black CFL 24 watt is the particular kind. They're just your typical, spiral shaped, black bulbs that produce UV-A. However, when using one of the bulbs in a lamp to take some UVIF photos of a cool rock, I noticed a particular scent. I'm not sure if it's ozone exactly. I've smelled ozone before, albeit many many years ago. It was more like the smell something really hot has, if that makes sense. Am I likely just smelling dust being heated up by the bulb, or is it possible for a blacklight to leak UV-C to produce ozone? I hope this isn't a dumb question, as I realize it's probably very unlikely to be the case. Nevertheless, wanted to know if anyone has had a similar experience and knows the cause just to put my mind at ease that I wasn't blasting my face with UV-C. And yes, I was wearing sunglasses for eye protection at least :)

SAFETY WARNING: UV-C is dangerous to your eyes and your skin. UVP DOES NOT SUPPORT USING UV-C ILLUMINATION. [UV SAFETY] UV-C Light Dangers I purchased a UV 10w Germicidal Sterilizer Lamp LED UVC, to test. The lamp that they sent had no marking or brands as shown in the ad. With the extra precautions of covering myself up & protecting my eyes, I went ahead & tested the lamp. When I turned it on the room had a nice ice blue glow, not unlike a 6000k cool white LED light. Placing my 250-850nm spectrometer in the light confirmed the spectrum of a cool white LED, but NO spectrum below 400nm down to 250nm. So what is going on, this is supposed the be a UVC lamp ? Strangely, to me the lamp wasn't 6000k BUT 1750000k instead. So wow what is going on ? Feeling ripped off, I went to my UVC fluoro lamp & placed the spectrometer in the light & there was the familiar 254nm spike, & low & behold I read 1750000k colour temperature. I smelt no ozone either. So what could this lamp be producing ?

5 Watt UV A, B & C Light This UVC light uses a thin film to filter for UV A & B from the UVC light. What are these films & where can I get some Please ? https://www.ebay.com.au/itm/Way-Too-Cool-5-Watt-THE-TRIPLE-Shortwave-Midwave-Longwave-UV-Light-w-HOYA/143848385729?_trksid=p2485497.m4902.l9144

Ok, disclaimer first - UVC is extremely dangerous, please do not attempt to use it without fully understanding the risks involved. Background to this work. I've been seeing everyone playing around with UVC, and had assumed that there was little point even trying it with the cameras I've got. A few weeks ago I bought a couple of 254nm 8w tubes to fit my UVP lamp, and today thought I'd just give it a go with my monochrome Nikon d850 (which has a quartz coverglass instead of the usual WG280) and Rayfact 105mm UV lens. Setup. 2x8W 254nm tubes in a UVP lamp, no filter on the lamp. Subject a vase with a couple of feathers in it, and a 20% diffuse reflectance standard. Filters, a 254nm bandpass filter from the Sirchie forensics camera, WG305 2mm and WG295 3mm. Camera, monochrome converted Nikon d850 with fused silica window from MaxMax. Lens, Rayfact 105mm UV lens. Settings, ISO400, f8, 30s exposure for the UV images. Whitebalanced in Darktable and reduced in size in XnConvert. Images shown with reduced resolution, but full frame. Firstly, image with visible light. Now with 254nm lamp and the 254nm bandpass filter only. So, with the 254nm lamp and bandpass filter I get an image (which I wasn't expecting to be honest), and because the glass of the vase is opaque at least some of this is UVB or even UVC. Next I tried putting a couple of different longpass filters in front of the 254nm filter. The aim here to try and block what the 254nm filter should be letting through, while letting through the out of band areas of the 254nm filter. I did this to check for leaks. With the WG305 2mm in front of the 254nm filter. And with the WG295nm 3mm filter in front of the 254nm filter. Both the WG305 and WG295 filters resulted in a reduction in the image brightness, but they did not eliminate the image, which suggests to me that there are some leaks in the 254nm filter in the longer wavelength regions. But it also tells me that most of the image is coming from the UVC region, which I did not expect. I must admit, I hadn't realised when I chose these two long pass filters that the 254nm one had such a long tail on it. Perhaps in hindsight a longer long pass filter would have been a better option. EDIT - Although looking as closely as I can at those WG images, the vase looks dark which would suggest leakage in the UVB/C region, so perhaps it is coming from the overlap region? More work needed there I think. Something to consider is the filter transmission spectra and the light irradiance spectra, which are given below (full range and then zoomed in on the UV region). Yes, there is some overlap between the 254nm filters and the WG ones in that 280nm to 300nm region, but it occurs at a region where the light is not really emitting anything, which makes me think that the 254nm images are really driven by that big 254nm line in the lamp. It also tells me that even good filters for UVC run the risk of letting enough light through in the out of band regions to contaminate the image - OD4 is no longer good enough, even with a light source like this with a really strong 254nm peak. I learned something new today - don't make assumptions about cameras capabilities before testing them. Sorry for any typo's, I'll go back and proof read when I have a minute.

Could I not try the green banana test with my LEDs? Of course not! It is a must with UVC. So, I took a greenish banana (not really green, but it still has some green) to test this. Green bananas work better than yellow ones, for some reason. It is surely due to chemicals present only in unripe bananas, as this is almost surely a chemical reaction caused by the energetic UVC photons. For testing, I chose the green areas of the banana. For both tests the LED was run current-limited at 50 mA without an heatsink. The output power, if it is a third of the maximum, is around 3 mW. First, I tried with the LED at some distance from the banana, and a plastic thing that blocks UVC to cast a shadow. I irradiated like this for one hour: After one hour, I turned off the LED and took a look. There was no visible discoloration. Since this was probably due to the very low intensity, I placed the LED much closer, and irradiated for one hour again: And, after waiting for another hour, I took a look, and this time it was a success! It must also be noted that this browning/discoloration effect sometimes takes hours or days to develop AFTER the initial irradiation. Kind of like sunburns. So I will update you tomorrow if I find some differences.

I have a KuangRen Macro Twin lite KX-800 that I bought for Macro photography. A couple months ago, out of curiosity, I decided to removed the two plastic front panels to see if I could modify the twin speedlite for UVIVF. The speedlite tube looks similar to Yongnuo YV560IV that I modified for UVIVF. So I placed two ZWB2 filters and surprised to discover those two small speedlites produce enough UV for UVIVF photography. I don't have any equipment to test how much UV the twin speedlite produced but still! What a nice surprise! I really like how convenient to use the Macro twin flash for my field observations. I document UVIVF on wildflowers for INaturalist. I am thinking to change the LED emitter of focus assist light to an UV 365nm LED emitter. Is there anyone you would recommend who would modify my Macro twin flashlight? Thank you! Michelle

I first read about Laser-Stimulated Fluorescence (LSF, sometimes also called Laser-induced Fluorescence, LIF) in the paper, "Laser-Stimulated Fluorescence in Paleontology" (Kaye et al., 2015) which has spectacular photos of fossils produced by this method. The main advantages of LSF over UVIVF is simply that laser beams are (1) columnated, so it's possible to do fluorescence photos at a distance from the subject where a torch is impractical, and (2) extremely intense, depending on the laser, with the possibility to see faint fluorescence which would otherwise not be able to be imaged. My main motivation is actually item 1 — I would like to do fluorescence photos of large objects (especially the kind of faded signs that I used Independent Component Analysis on here). I highly recommend reading that Kaye et al. paper, which has almost all the information you need to get set up, as well as beautiful fossil photos. Kaye and another student have also written another paper on LSF in caves, which has gorgeous photos. I highly recommend both of these papers as "required reading" if you are interested in pursuing LSF. If you prefer to get your information in audio format, both authors talk for 38 minutes , which has some info that isn't mentioned in either of the papers as well as their personal experiences. Basic Setup and Methodology (from Kaye et al., 2015) We are all familiar with the light painting technique, but in this case, because lasers usually produce only a single bright spot, it isn't practical to directly implement it. Instead, the optimal setup is a laser with a special lens called a Powell lens which spreads the beam into a uniform line. If you buy a laser online, they will sell you one with a "line lens" but it will be a cylindrical lens that does not produce uniform flux. Powell lenses are much better for this application. They can be purchased many places and I haven't bought one yet -- I am using a cylindrical lens for the experiment below, however I plan to get a Powell soon. The authors recommend Powell lenses that have very small angles to keep the irradiance high and keep the beam easy to direct. ThorLabs link to Powell lenses For the choice of laser, in the papers above they usually use powers between 150mW and 500mW and 405nm. Technically it is a violet-induced fluorescence rather than UVIVF. I chose to buy a 100mW laser with a 120 degree cylindrical lens (cheap Chinese laser, $30) for my first attempt, and then once I understand the method and limitations better, I plan to buy a more powerful laser and a Powell lens of perhaps 10 or 20 degrees. WARNING: Do NOT use any laser beyond 500mW! Not only is it overkill for this application, laser power can be non-intuitive for people who haven't used lasers before: a 1W laser can burn matches, pop balloons, start wild fires. A 5W laser will cut plastic sheets nicely and put an eye out with ease. For filtering the source, no filter is needed on 405nm lasers, but if you try a green laser, you may need to filter out infrared with a BG38 or something because green lasers are really infrared lasers that go through a crystal that converts the beam to green. Many of them leak infrared, sometimes dangerously. For filtering the camera, I am currently using a Tiffen Haze 2E filter + BG38 2mm just like I use for other fluorescence photos. I am not yet sure whether the 2E has enough blocking at 405nm to stop the laser. Some experiments need to be done to verify this. The authors have built a motorized setup to do the light painting automatically. This is not necessary, but in my first test I found that it's very easy to linger too long in one location with the laser-line and make an accidental bright spot. I think building a motorized setup is a good idea to get uniform results. Safety Lasers are a completely different beast than the sources we are used to on here and need different safety precautions. 1) You NEED safety glasses. They are not optional, not even for the lower end of the power scale mentioned above. These are Class IIIB lasers, they can cause eye damage fairly quickly at close range, even when spread into a line. - When purchasing safety glasses, you must select glasses that filter the wavelength of laser you are using (405nm in this case) and with sufficient OD for the power of laser (mine are rated to OD6). - Look for glasses that are wrap-around and protect the sides and bottom from reflections. With lasers, the reflections can be almost as bad as the original beam. Even DIFFUSE laser light over sufficiently long periods can cause eye problems. 2) My friend who has worked with lasers cautioned me that the safety glasses must NOT be scratched because that significantly weakens their protection, so always keep them in their case when not in use. 3) All reflecting items (mirrors, shiny surfaces) should be covered beforehand. 4) Outdoors, lasers should not be used around other people. Obviously never shine them where they might hit a driver, a pilot, or shine in someone's eyes. As well as immoral, it's very illegal in the US (and probably in most countries). My plans with regard to imaging signage is to pick locations that are abandoned. 5) It's probably a good idea to know beforehand whether (or at what distance) the beam produces significant heating. You don't want to set your subject (or worse, dry vegetation) on fire. Goes double if you live in a dry place like the US southwest. Know before you go. In addition to the above, I found a forum for laser hobbyists that has a nice sticky on getting started with lasers, including an (even more) elaborate section on safety than I included here. First Test Here is the same gourd that I did UVIVF on previously. The exact same color profile was used here to allow for comparison. The laser was light painted from very close to keep the intensity very high. The beam spread was 120 degrees, which is inconveniently large, and no significant heating was observed at any distance. LSF, Micro-Nikkor 55mm/2.8, BG38 2mm + Tiffen Haze 2E Laser: 405nm, 100mW (nominal), cylindrical lens, distance roughly 1/3 meter. F/8, 30", ISO100 For comparison, here was the UVIVF result from before. Note that several months have passed and additional mould has grown. Final Notes My experience with the Chinese seller, Laserlands, was atrocious. They did not respond to repeated emails, nor to Skype, nor to a Facebook contact, for weeks. I will not buy any more lasers from them and would recommend keeping far away. Also, my intent, if Andrea agrees and if there's sufficient interest, would be to expand this post into a sticky.

[UV SAFETY] UV-C Light Is Dangerous NEVER look at a UV-C light. NEVER let UV-C light hit your skin directly or by reflection. UV-C light can cause: severe burns of the eyes and the skin, and DNA damage from broken chromosomes. When working with UV-C illumination, you MUST: cover up completely, and have strong ventilation. I bought 5 pcs 1 W 265 nm LEDs on eBay. I can later put a link for purchase if someone is interested (as always, I have no affiliation with the seller). Link: https://www.ebay.com/itm/254318067890 I ordered the LEDs already soldered to a 20 mm copper star PCB, since my soldering skills are not that great and I don't have a heat gun or solder paste. I took one out for testing, I don't know how I will use the other four but I wanted to also build a 265 nm torch, so that's one use. The LEDs are rated at 1 W input power and 8-10 mW output power. Efficiencies around 1% are typical at these very low wavelengths, so the numbers given make sense. They are rated at 150 mA of forward current. I don't have a meter to measure the output power, but I can measure the input power. When the LED is cold, it requires 6.3 V to run 150 mA across it, and that's 0.945 W, very close to the advertised 1 W. For the tests done below I ran the LED at about 80-90 mA without an heatsink, and it became noticeably warm but not hot. I can run it at full power for a couple of minutes, but then it becomes too hot, so a small heatsink is required. A downside of the very low efficiency is that almost all power (~99%) is converted into heat, while an efficient 365 nm LED can reach 50% efficiency, so only half the power becomes heat. The LEDs also have a lens on top, which must be made of quartz or similar, and according to the seller the view angle is 60-80°. I measured ~64.5°. All photos were taken with my smartphone. For the 365 nm shots I used a 365 nm LED torch with a ZWB2-like filter, which is the first UV torch I bought. I could have used the Convoy, but I usually keep it safe and use it only when I need an intense beam. This is how the LEDs arrived. The "holder" on top was longer and bent, and I cut away the excess portion with a pair of pliers. They probably gave me half of a 5x2 array. Looking at the LED with a pair of polycarbonate goggles on, the chip appeared bluish while the lens appeared more violet. Looking at the spectrum with a diffraction grating I saw a full rainbow from violet to red. The output actually appears to be quite clean, but filtering it would improve it for sure. Also, very carefully, very briefly and with the LED at low power I looked at it without protection, and it looked no different than with protection. That was to be expected, as my cornea and lens completely block UVC. I am very aware of the dangers of UVC light, and I always used eye protection while working with this LED, and avoided getting my skin too close to it. The output is very low, mercury-vapor lamps are about 35% efficient (source here) and so a 3 W mercury lamp is already ~100 times more powerful than one of my LEDs, but I am still careful. The output, while being low, is still usable. Combining several of these LEDs together would be better, but just one of them is enough at close range. In my limited experience, I noticed most things have very similar fluorescence behaviours under 365 nm longwave UVA and 265 nm shortwave UVC light. Paper still fluoresces bright blue, yellow and orange highlighters behave like normal, and most things appear basically the same. There was one big difference which I liked a lot, and that's banknotes. This is a 20 € banknote under normal light (it should be the new one): The same banknote under 365 nm UV: The fluorescence appears greenish, but is actually yellow. Now, under 265 nm UV: The color changes to a beautiful deep orange. It reminds me of older Euro banknotes, which had yellow and orange fluorescing inks. Also, there is an hidden "€" symbol visible under UVC but not under UVA or visible light, so this color change may be intended. Another nice thing is that, finally, glass appears opaque. Some plastics are surprisingly (partially) transparent, but most aren't, and all glass I found around isn't. I tried with a quartz crystal, which is the only quartz thing I have around, at it looks to be transparent (it should be). A paper sheet was put under the pieces of glass to "see" the otherwise invisible UV light. Below an (empty) glass. Visible light: 365 nm UV: 265 nm UV: Old magnifying glass, visible light: 365 nm UV: 265 nm UV: About filtering, 360-type glass doesnt work, as it blocks UVC. 340-type glass, although it reaches deeper, absorbs UVC almost completely. The only option is to use the 330-type (Hoya U-330, UG5, ZWB3 and so on) as it transmits 265 nm well while blocking most visible light and some IR. Not perfect, but does something. The best thing would be to use a dichroic filter, but those are hard to find with good peak transmissions. As a reference, here is the normalized transmission curve of 1.5 mm thick UG5 glass: As a test, I tried with 2 mm thick ZWB2 glass: Visible light: 365 nm UV: 265 nm UV: About the beam pattern... it isn't very uniform. I hoped for something better, but this is what I have: Not too bad, but could have been nicer. One thing these LEDs are great for is collimation with a (quartz/fused silica) lens. LEDs with an already partially collimated output (like this one, which has a ~60° viewing angle) are great to be used this way as you don't waste any light with a sufficiently "strong" lens (a lens with a pronounced curvature which has a short focal length while being relatively wide). The LED is also quite small, and this allows for narrow beams. If you want to use a parabolic reflector, it is much better if not mandatory to remove the lens instead. Overall, a nice LED.

Some, ah, interesting filter stack recommendations in here. I think the authors need to read our forum! https://www.academia.edu/9469495/Xenon_flash_for_reflectance_and_luminescence_multispectral_imaging_in_cultural_heritage_applications?email_work_card=view-paper They act as if S8612 doesn’t exist. Or even BG39!