LED Blacklights vs Flourescent Blacklights?

I have an event coming up where I'll be using blacklights, and now that blacklight parties are really gaining in popularity in my area, I think it's about time to invest in some. I don't need giant blacklight canons or Wildfire fixtures, as most of what I do is pretty small scale, 300 or less people.

I've used Elation UV Wash, and found that four of them really cover a 2500+ square foot room well, but my vendor is telling me how awesome the Elation Opti 30 UV is. He says it blows away the UV Wash. Having never seen UV LEDs, I'm wondering how well they really perform?

The idea of strobing and chasing blacklights is really cool, but my understanding is that blacklight work best across a broad spectrum, from 350 to 405nm, peaking somewhere around 370nm. These LEDs are 390-410. Isn't that kinda narrow, and more like a deep purple light than a true blacklight?

Thoughts on LED blacklights?

ya seems more violet/near UV... think UV is <400nm IIRC?

I've found blacklight/UV LEDs aren't very good at all compared to a nice MH fixture. Seeing as a heap of MH spectrum is UV anyway, they're pretty damn efficient too.

I've got a bunch of the Chauvet LED-UV wash lights and they work pretty well for the money I paid.

I still think the proper UV guns are better, but the LED stuff is much cheaper and pretty much bomb/idiot proof... Plus you get DMX control and the lamps don't break if someone's a bit rough unloading/rigging/loading them...

To be honest, if I'm doing the gig, I use my proper UV stuff, but for dry hire or specific events, I use the LED stuff.
For the money, buy a couple and see what you think? You can always FleaBay them afterwards if you don't like them...:)

Consider the fact that a 405nm laser is called a Blue Ray! It is violet, but you can clearly see it.

So peak wavelength is part of the question another part is directionality.

Then there is the issue of how fast you can turn them on and off.

James.

Metal halide with good dichroic filters, Not Woods Glass, if you can avoid it. But better Wood's glass then cheap plastic filters.

Z.

Quote:

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Originally Posted by WookieBoy

I've got a bunch of the Chauvet LED-UV wash lights and they work pretty well for the money I paid.

I still think the proper UV guns are better, but the LED stuff is much cheaper and pretty much bomb/idiot proof... Plus you get DMX control and the lamps don't break if someone's a bit rough unloading/rigging/loading them...

To be honest, if I'm doing the gig, I use my proper UV stuff, but for dry hire or specific events, I use the LED stuff.
For the money, buy a couple and see what you think? You can always FleaBay them afterwards if you don't like them...:)

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Are you finding they put out any true UV in addition to violet light?

The best LED UV units I've used in 5 years of promoting events with a lot of blacklight are the American DJ UVLED BAR16's - they are deceptively powerful for their size and put out an extremely wide throw & fluoresce UV reactive things nicely. I've used 4 to cover a room with a crowd the size you are describing to good effect.

I like them because they're much smaller than bulky tube lights, they don't pose a chemical hazmat concern if broken, and they are much more inconspicuous (easily truss mountable) and resilient; thus far less likely to get broken. They can be used to uplight cool decor elements or wall art, downlight on-stage performers who wear UV reactive costumes, or blast at the crowd from front, side or back (I prefer @ least two or three angles on the crowd).

http://www.americandj.com/ProductDet...temNumber=1892

Thanks for the responses. Lots to think about.

Mot UV leds are around 395nm and most fluorescent blacklights are centered around the 365nm wavelength. At work we have a bunch of the Wildfire HID backlights. There is a difference between the two. The LEDs are much closer to the visible spectrum and react differently than the shorter wavelength from the normal lights. I have a UV LED light from Phoseon that I have been messing with for doing some stuff with dyes, you can see how the light is more visible:

http://farm8.staticflickr.com/7197/6...fd82e021_z.jpg
IMG_1330 by macona, on Flickr

That light sells for about $4k.

This is what I was doing with it:

http://www.flickr.com/photos/6729211...7629551557170/

I have to hand it to you, those shots are breathtaking.

I think in the end, I'm going flourescent. I'd rather have less visible light and more UV reaction. I think I'm going with Elation UV-Wash, after all. I think it's my best option cost-wise, and power is usually an issue at many venues I work in, which makes MH difficult.

Thanks for the info!

I did sound for an outdoor psytrance festival a couple weekends ago where they used two of the metal halide blacklights, a load of 4' fluorescent tubes, and one LED blacklight fixture to illuminate everything. The LED light was clearly closer to visible spectrum. The event had the LED fixture washing the dancefloor from the back to illuminate the deco surrounding the DJ booth. It was blindingly bright on the dancefloor and to the DJs. I suppose if you could rig it so it just hits deco it would probably work just fine (it was super bright) but the crowd did not enjoy being in the light.

Sooooo...apparently, the Elation UV Wash is recently discontinued. Seems that on the lower end, a lot of manufacturers are dumping flourescent altogether in favor of LED. I found some UVA LED's which emit at 365-370nm, right at the magic number, but these aren't in any entertainment fixtures so far as I've been able to determine. They're also a bit more expensive, but still, you'd think that perhaps some higher end fixtures would start incorporating them. The lowest LED wavelength fixture I've found is The Brickblaster, by The Black Tank. They claim 385nm using a dichroic filter. I don't know pricing as of yet, but I've contacted them for information.

http://theblacktank.com/products/led-fixtures

I have 2 - wildfire units. Non DMX.

One is a 250w and the other is 400w.

I paid about $250 each used. I can easily do 300+ with those two. I use one for less than 300.

My point is if you want rich black light buy wildfire or similiar used. Save the money.

If you want strobes....use strobes. Just the way blacklight is on the eyes I think the effect is better when you leave it on.

Here's some video from a gig I did. They are positioned on top of the speakers.
I really should have had them higher.

http://www.youtube.com/watch?v=ofHh3X8HlVs

I found three new UV-Wash at a store on Canal Street in NYC after looking for about a week. To be honest, I was so fixated on finding the Elations, I never even thought to look for used Wildfire units. When I need more, that's definitely what I'll do next time. Thanks for the suggestion!

I like them because they're much smaller than bulky tube lights, they don't pose a chemical hazmat concern if broken, and they are much more inconspicuous (easily truss mountable) and resilient; thus far less likely to get broken. They can be used to uplight cool decor elements or wall art, downlight on-stage performers who wear UV reactive costumes, or blast at the crowd from front, side or back (I prefer @ least two or three angles on the crowd).

I know this is an older thread but I have found some 365nm (normal blacklight range) LEDs with decent luminous output. Unfortunately, they are not cheap.

http://www.mouser.com/ProductDetail/...cmDSH4XQJAc%3d

Thanks for the link, i have been looking for something deeper UV then the leds i have made by Cree, they where still bloody expensive when they came out, i think they where around 20 each when i bough in a small quanity

The biggest thing I have found to look out for with UV LEDs <370nm is the luminosity. Most of them are low. I found some cheap 365nm LEDs on eBay but the output is dismal.

LED Engin: Luminous Flux/Radiant Flux: 800 mW
Cheapo LED on eBay: Luminous Flux: 50~55mW

Here is the link for the cheapo eBay ones but I don't know that I would bother:
http://www.ebay.com/itm/3W-365nm-UV-...MAAOxyXDhScoqb

Thanks, i ordered 4 to play with, i dont need a long range, i just want to light up a uv responsive flag that's in my living room, i can mount them behind my tv to light up the flag, i have some minerals that do respond to long wave uv, i guess i can be the test subject for them and i will report back on how they work, i only need a range of a foot or two, my main florescent uv set up is total over kill for that operation, for the rocks i have i use UVC and need shielding and filter glass that's very expensive.
but this is what UVC can do Attachment 49612

I use a germicidal lamp with filter glass over the lamp the blocks the visible light from the lamp, of note though you MUST have eye protection, polycarbent (plastic) safety glasses work great for your peepers and a normal Plexiglas works very well as a front shield, i would like to add a UVB light in the future and some even respond to UVA

The sub 4 dolor 365nm 3 watt leds came into day and they are better then i had expected, i don't have a way to measure the output in mw but here is a shot from my living room, exposure time is 2 seconds with the aperture of about F2.0, the led is 8 feet from the wall.
Attachment 49733
distance about 3 feet but this rock normally florescence under short wave UV
Attachment 49734
the led does have some visible light but is better then what i was using, i am running one led at 700ma, 4 will be over kill for my original idea
Attachment 49735

Nice! Is this just with one LED? If so, that is better than what I expected as well. I am wondering if you could use a UV dichro or a woods filter to kill the visible light. I am curious if that would work on the higher output LEDs. I have no doubt the higher output LEDs generate more visible light as well.

yeah it's just one. I dont have a dichro that would do that and the filter glass i own is for short and medium wave, i could try my medium wave one, i would need to pop it out of the light though, it's in a portable UVC/UVB light that i take with me when i am out hunting at rock shops, i just got it working again, it had a bad lamp and corroded battery terminals from storage but it does now fully work, i could try that, the glass is just hot melt glued on, on my portable, my larger UVC only the filter glass is silicon-ed in, i took a normal fixture that you find at Halloween stores and put a UVC lamp in and made an aluminum cover and glued in hoya UVC pass filter glass, at lest i think it's hoya, i just looked at http://www.uvsystems.com/index.php for LW filter glass and it's much cheaper then the SW stuff so if my budget permits i will get some filter glass from them and test it
They had the filter i could use but a damned 35 dolor minimum order limit
Now the dichro glass i do have for UV reflects it so i will try an experiment when i can find the gass in my hoard

When i hold my hand over the led i can feel the heat from the light it's self, that surprised me a bit too, i have it mounted on a heat sink and am driving it with a jaycar kit built http://www.jaycar.com.au/Kits%2C-Sci...logue/p/KC5389 driver, it's large by todays standards but drives this thing right at 700ma and i think i can series two. I have a higher frequency Chinese switch mode driver but i have blown leds with it lol, little touchy on the voltage

one thing now to test as well is the lumen maintenance. I did find a kit for a uv light sensor so that will be the next project to see if i can measure the output, originally i wanted it to measure the uv that my lizards must have. https://www.adafruit.com/products/1918 hopefully that will work

Interesting stuff! I've been looking at these UV LEDs for a while as well. My goal is to provide enough UV light to fluoresce walls in a 19 ft x 10 ft space. So far, the DMX fixtures using the 365nm diodes are still quite expensive IMO. (US$2,800 for 60W!) I purchased one of these 10W 365nm chips to experiment with.

I really wish I had the ability to measure luminosity from these as Chinese vendors frequently overstate the specs on their products. That said, they are so cheap, even if they doubled their actual output in their specs, it still looks cheap compared with purchasing ready-made fixtures.

-David

I have found that my laser power meter a sper scientific 840011 will respond to these leds but i don't know what the correction factor should be as it's outside of it's listed response curve, it's lowest is 400nm with a correction of x10.4 but given that i am measuring about 150mw with the sensor right on top of the emitter, there is some visible light at that distance and at one inch i get about 41 mw, the uv light sensor i built i am still playing with, i think the formula from adafruit may be wrong, still working on it though.
I did manage to kill one, i was using it on a Russian simple drive and the interlock is different, it came out of interlock with the current way to high for a split second and blew the diode. I have found that these types of leds are more intolerant to spikes then other more conventional diodes are. in the past i used a Chinese constant current driver to run 4 higher wave length uv leds and blew the entire array when i was trying to adjust it's set point, i did get it to correctly run another 4 after i learned from my error, these 365nm diodes i have been using a kit built driver for luxeon star leds and runs 2 of these in series very well. the kit is older but jaycar still has them, called KC5389 i think

I have been running these as often as i can to try to get some idea of the lumen maintenance these may have, although i have not been running them at elevated temps yet

I have run into some problems with the uv leds, the two i am running with the jaycar driver have both had the outer lens melt, one totally failed, since they are two in series i added resistors in parallel to make sure each led is getting a balanced voltage, i am using 330 ohm .5 watt resistors to make sure each led is running at 3.7 volts with a total current of 660ma and still had a lens fail after that arrangement but that led is still operating, there is some type of clear rubbery coating over the led element, i have a led mag light brand flash light do the same thing, i have contacted the vendor for more information. I also checked the driver it's self for ripple and find it's ripple is at 80mv with a period of 70 micro seconds so i doubt that has caused any damage, the total failure of one led could have been due to an uneven voltage across the leds and added the resistors to balance that, i have never liked operating leds in series for that reason and these may not be as robust as a visible wavelength led. i am going to try and get the vendor to replace the leds but i suspect i will still have a lens failure as it seems to just be a polycarbante lens held on my silicone glue. mouser is also out of stock on the better quality led with a listed lead time of 14 weeks :(
I have these mounted to a heat sink that is over kill and keeping them running fairly cool. I hope this info is of use to any one interested in these and testing goes on

done a little bit of more resurch and found that the better quality 365nm uv leds have a glass outer optic and not the crappy plastic one, my remaining array is still running and the vendor did refund my money for the two that had the outer lens fail and since i included the resistors into the array they seem to be operating in a normal fashion for now, mouser does have other leds from the same maker listed in stock but at less then half of the one that is out of stock and sadly the want the same amount of money, i did come across the Nichia NCSU033B that has a glass optic so that is a possibility as well and has a nominal output of 540mw with a min of 495mw

here is the part from digikey http://www.digikey.com/product-detai...032-ND/4976722

and they have them in stock

I just also scored a Nichia NCSU033B P33D22 that lists a flux of about 495-540mw, i was not expecting the vendor to except my offer under his auction price so i went with the led engin branded LZ1-00UV00 365 with a min rating of 800mw - 1250mw. I should have that in my paws on monday. and with the eBay cheapies they are still running fine, since i added the balancing resistors i have so far not have had any fail, next month i will buy the UV pass filter glass and make one into a mineral light for my rocks, errr minerals yeah that sounds better, dragons should not collect rocks but minerals are fair game and this should replace the crappy UVA CCFL that are normally used in computer cases.
If you guys want me to try and collect more data i can try but i need some interest from you guys or the experiment may not be worth it.
What other uses do you guys have in mind for these? or am i just babbling about something that others have no interest in?

Hey Draco! Actually I find this all very interesting. I have several diodes on the way to play with but my goal is affordable DMX controlled fixtures. I wish I could figure out some guesstimate of luminescence but I suppose that is at least as much a factor of wavelength and the uv paint as much as output power. Anyway, I look forward to experimenting and appreciate you sharing your findings. Be sure to post some glowing mineral pics when you get there.

Cheers!

David

I dont have any real data yet but to my peepers the one made by led engin is indeed brighter then 2 of the cheep ones combined, i am running it at 650ma and i think i can goto one amp, i need to adjust the driver to get it to that level, i have a second controller on it's way from Australia that will have the data i need, i may need to change out a current sense resistor to bring it up to 1 amp. I have found that these types of leds are more sensitive to mistakes then a standard led. I could go with a newer design but the one from jaycar is made to run on 12 volts and has a low battery shut down and that i need for camping, i should have it this week i hope. but sofar the led engin is worth the money, at the given current i think it's outputting about 300mw but my meter is not reliable at 365nm, the conversion i am using is at 400nm so there is i believe a large degree of error right now, it's most likely to be more like 400mw

sofar i am impressed enough to order a second led engin device, now i just need to find a correct calculation for my uv sensor, this is the UV sensor https://www.adafruit.com/products/1918, the equation for UV index seem right but the one for flux does not make sense.

"Extend your light-sensing spectrum with this analog UV sensor module. It uses a UV photodiode, which can detect the 240-370nm range of light (which covers UVB and most of UVA spectrum). The signal level from the photodiode is very small, in the nano-ampere level, so we tossed on an opamp to amplify the signal to a more manageable volt-level.

This sensor is much simpler than our Si1145 breakout, it only does one thing and gives an analog voltage output instead of requiring a complicated I2C setup procedure. This makes it better for simple projects. It also has a 'true' UV sensor instead of a calibrated light-sensor. To use, power the sensor and op-amp by connecting V+ to 2.7-5.5VDC and GND to power ground. Then read the analog signal from the OUT pin. The output voltage is: Vo = 4.3 * Diode-Current-in-uA. So if the photo current is 1uA (9 mW/cm^2), the output voltage is 4.3V. You can also convert the voltage to UV Index by dividing the output voltage by 0.1V. So if the output voltage is 0.5V, the UV Index is about 5."

that's from there web site and i would be grateful if some one can help me understand that formula, i think it's wrong but i dont know

with that formula for UV index i get 43 so i am thinking i am over range

i just posted on adafruit on there forums to help make sense of the formula, i added a reverse polarity diode to the led engin model and am going to take the same protocol that i use with laser diodes, i believe i lost one due to ESD and the led engin ones have a reverse Torrence of only 5 volts. pictures will be coming and the replacement cheapie leds are now in the states but they are the last i think i will order given the huge diffrence in the radiated flux, i am tempted to add a lens to mine buy it's a plastic one made for a visable light star and i have a concern that i will solarerise the plastic

I've been on the fence about ordering the LED Engin diodes but they sound like they are the way to go. How would your rate them to a CFL blacklight or even a 48" fluorescent tube?

BTW, thanks for testing these out! :beer:

I am in the process of cleaning my front bed room where i have a 2 tube fixture and i am asking on adafruit's forum but for a point source light source the led engin by far is the best led to go with, one of my drivers failed but did not kill the diode, i missed a solder connection of the drive ic and destroyed a 2n3904 and the main
FZT1151ATA transistor and have that coming in the mail this week

mental note to self, don't assemble kits when you have not slept in over 24 hours lol. the older school luxeon driver from jaycar seems still the best way to go, unless some else has a flexible driver for different led currents, on fleabay i find all kinds of drivers but they are either mains powered or made for a flash light with a fixed current

Right now i am still trying to find my main uv light power meter and got the second led back up and running on a simpledrive controller but that's a linear driver so it wastes quite a bit of power but both of the led engin 365nm diodes i have been running at 950ma and only need a modest heat sink, all of the Chinese made leds have since failed, one died from my fault and two had the acrylic lens melt and got a refund for them, pictures will be coming soon but by far i believe they are the best on the market for the power level, i want to try to add optics but all that i have are acrylic and i think they would solarize in time and attenuate the power out put.

I have the simpledrive on the same heat sink with the thermal sensor attached so i don't damage the driver but with only the led on the heat sink they run a lot cooler then the Chinese leds even though there output is almost 10 times the output flux. for events these guys could be hidden a lot easier then a florescent tube, when my finances allow it i will buy the hoya filter glass to kill what little visible light the diodes make.

I would like to arrange these in series but my experience with the Chinese leds even with balancing resistors make me very wary of doing that, these seem to be close to the intolerance experienced by laser diodes and i have been putting IN4148 or IN914 reverse bias on the leds. the reverse voltage for the uv led is only around 5 volts and the maker just lists that reverse bias is not recommended.
I have one Nichia NCSU033B P33D22 on the way from Hong Kong on a copper star base for evaluation as well, along with two more of the Chinese leds on the way (i ordered them before i killed the others).
I don't know of a way to safely series these at the moment and am open to suggestions.

I know the led engine ones wont compare to a 15 watt or higher fixture for output but they are much easier to hide. The leds i have now are all on the star base and the maker recommends 3 screws to mount them, the led it's self is on a ceramic substrate with a glass optic so the same torque on the screws is important and use plastic washers to avoid shorting out the solder pads, i made my own with a fixture i use for making end plugs for the fireworks i make but the washers are easy to find at most any hardware store.

On a side note i found a bunch of glow in the dark stars stuck to the ceiling in my bed room i was unaware of, the former owner must have had kids in that room, lol now i want to add more, even though they make some visible light at the led it's self it does not seem to carry that far:cool:

sofar so good, i have been running the led engin units at 950ma and so far no problems, i have parts on order to find the driver i damaged and i have 2 more of the cheap ones that i will be testing at there rated power, they do work but as i said are very intolerant of mistakes in drive voltage and i will not be putting them in series, i am going to order a 3rd old school luxeon driver for that, it's odd i cant find anything that offers the features of that obsolete controller

I found my uv meter! i only had to empty half of the room :)
now for some numbers, i did the tests with the sensor about 1cm from the led's lens with a little error as i did not want to make contact with a metal caliper.
The Led Engin at 680ma i got 95mw/cm^2
910ma i got 134mw/cm^2
1 amp gave me about 150mw/cm^2
The generic fleabay led at 680ma was 63mw/cm^2
I did not go higher in current as 700ma is the spec and these don't do well above that, now i am going to keep track of operating time, the flux i got on the generic led is brand new, the flux on the Led Engin is after about 10 hours of operation and my second one has about 30 hours and at rated current i get about 155mw/cm^2.
No optics where used except of course the naked leds

Since i started testing with approximately 42 hours the generic uv led test fixture fell over on to a strip of foam that borders the glass surface it's on , melted some foam and created a hot spot and then, the out lens did melt, so i removed the cheap acrylic dome and have it back into testing, the LED Engin is still running happily with nearly no luminace loss in either uv diodes. the generic is just that a a low cost item, i think they would be good in a uv flash light or in an enclosed luminary, the optics need to be kept clean or the heat of contamination my cause dark spots that then just melt the plastic dome.

Now i do have a question, does any one know of a supplier for these little domes, preferably made from glass with the same diameter of about 5mm? so i can protect the die from air? the generic has a type of what i could only guess a silicone type goo on the inside to keep air away from the uv led die it's self?

one other thing that popped into my reptilian noodle that i have is with the power density of these devices and close up i would not recommend looking at the source for any length of time, in my tests i have the led's behind me, even though it is UVA i have gotten that sand in the eye feeling that i got a bit too much uv, but that was close to the emitter and these have a wide radiation pattern so people a few feet away i dont think there would be risk,
I have been moving stuff around in my lair and misplaced my camera tripod so i will have pic in the future, but for use outside at an event with lots of florescent paint or clothing around i can see these being viable for hiding them in different areas for different effects and the LED Engin would fit the bill for that and use the generic uv diodes in more of a portable flash light as long as the optics are kept clean.
as stated i am using an older driver made for the luxeon series of leds and uses a buck regulator and runs in the lower khz range and some times is audible as a slight hiss and these where engineered to be used on lead acid batteries as they have a low power shutdown via a jumper setting, other wise they will run on lower voltages.
These drives i have use an MC34063 switching regulator ic. I have one more coming and next month may be another, mainly that i feel once there stock is sold out i doubt they will order more. i know there are small drivers available but i do like these more and the only part that is hand made is the main inductor and that's easy to wind
Attachment 49991

on Friday there was a fundraiser 5k run at the local high school and was helping a friend involved with the project, after taking note that every one was in florescent clothing and would be running at night i ran home and grabbed my two LED Engin leds two batteries and set them up at the finish line having them mounted 2 feet apart and aimed up at about a 45 degree angle from the ground so they would light up runners at the finish line and to my surprise it worked out very well, sadly my camera's battery died so all i got was a few blurry images i will try to up load later but i had noticeable illumination out to atlest 20 feet from the two point sources of UV running at almost full power, i ran them at 910ma, this was my first test for them outside and i am very pleased by the results for this type of event, it makes it so easy to hide or place these in locations where normal black lights would not be practical, with filter glass i think i can make them nearly undetectable and can put them in a line array with the leds being about 2 feet apart.
so my next plan is to skip the cheap ones and go with the led engin with it's glass optic, i have found the plastic optic on the cheap ones if contaminated by dirt or dust will cause the lens to melt and fail, i think my two cheap ones i will make into flash lights as they seem to work better for that application and can have protection for the plastic optic.
both of the better led engin i have had no deaths and the lumin maintenance has been very good, no notice in loss of output with about 40-50 hours on them.
i found 2 of my florescent fixtures and will be comparing them but in terms of portability and needing mains power that they would only be useful in a build it location

if any of you have been on the fence on buying the led engin ones i doubt you would not be happy with them, the point source is i think there biggest strength, easy to hide and can run on battery depending on your driver

got the Nichia NCSU033B Ultra Violet UV 365nm LED II Copper , 540mW for about a week now, not the same power level, i get about 57 mw/cm^2 at about 1 cm from emitter, the LED Engin are still going strong with out a noticeable drop in power. The cheapies are still going as well even though the plastic lens failed and had to be removed the led is still maintaining measured output, if you use the cheap one i would recommend protecting that plastic lens and keeping it clean and treat these like laser diodes, picks will be coming soon, just have not had the time yet

this is a good thread, thank you draco for evaluating/testing out the available LED's, I hope to be able to use this info someday

Well I have been running these higher quality uv led's since my last post and they are all operating correctly with about the same output power and on the same Jaycar kit built luxeon star drivers. I just got in long wave pass filter glass from UV Systems to kill off some visible light from the led it's self.
One thing to note about the cheap Chinese made ones, they have all since totally failed and I ran them with in the manufactures spec's so they are not worth bothering with unless you operate them interdentally and keep the plastic lens very clean.
The LED Engin and Nichia are worth the extra money :)

Following this thread. I've been increasingly interested in UV leds so this is really good info. I bought 100 3W 400nm leds a few years ago for some projects and had the same lens issue you mentioned. extended use caused a browning in the center of the lens and eventual deformation and detachment. It's ashame too, it's much nicer spending $1 on an led than $35 lol. but I guess that explains the price difference.

I wanted to gibe an update on the leds I got just about 2 years ago
https://www.digikey.com/product-deta...032-ND/4976722

They are still going strong and have great lumen maintenance over the years so if you need 365nm leds that work very reliably.

Sadly they are still 35 bucks each but with these you get your moneys worth, all the Chinese leds I used as comparison died a long time ago, The nicha and LED engine have been great over the years and are well worth the money

Yeah, products made with these diodes still reflect that high part cost. Swamidog saw a nice Wildfire display at LDI this year that incorporated a bunch of these. At US$2800/each for the 60W version and US$3,601 for the 120W version they are powerful, but still painfully expensive. I suppose there are many ways to part with a lot of money in Vegas that leaves you with a lot less satisfaction . .

-David

the Chinese ones seem to use a silicone goo under a plastic optic and they just solarize, turn brown and fail, spent some time on flea bay to see if they have cheaper ones with glass optics but heck if you are going to build one, so with the good brand named parts or it's not worth the effort, they are kinda sensitive, so a LASROB or a switching diode I think are needed on the deices, simple switching diodes have work well for a few years, and you can drive them with laser drivers or drivers made just for them and that's the way I would go

When the silicon fails, does it fall off and leave the die still working? IF so, maybe you can place the engine in an air tight box and pump in nitrogen. You can then put some form of optic over them to collect and focus the light....OR. Get the right UV safe silicon and recoat them. At 1.00 a piece it might be worth trying.