365nm UV LEDs???

[Hayden]

Hey guys, I'm wanting to make a UV LED flood light and I'm having trouble finding some true 365nm LEDs
I know there's plenty of UV cobs, strips, crees on ebay BUT there's a lot of bogus ones there too as the majority of them are 395nm.
Strips would be the best for mounting and wiring but unless I can get ultra bright LED strips then I'll have to go several crees or a couple of cobs.
I've used a 100w uv cob light before but you get a lot of visible light that kills the glow effect so I'd say that light would be 395nm.

Anyone know where I can get genuine 365nm ones from? any type: cobs, strips, cree
Cheers

 

[DoctorMemory]

All over Ebay. You are correct that 395nm is really violet and visible, 365nm is UV. But note the 365nm will not put out the same optical power, glowing things will be brighter under the 395nm. And note even the 365nm has some non-UV light, you'll need a filter for real black light.

 

[Hayden]

Thankyou so much for your reply
I think I prefer the lower wave length as I have put a mercury vaper discharge UV lamp up against a 100w UV cob and they both make things glow basically the same BUT the 395nm LED cob has a lot of visible light that tends to light up the surroundings that aren't UV reactive. I think the mercury vaper discharge would be a lot lower wavelength?
Would it work if I put more 365nm LEDs than I anticipated into my project to composite for the lower wavelength not putting out the same optical power?
I have heard of filters but what are the best to get?
Cheers

 

[mercrazy]

i've used filters similar to these. you have to get specific ones for wavelength you're using. they will stop almost all visible light but will reduce some of the uv.
https://www.ebay.com/i/232899453207...kdjQvg6YcvKRxN4Y7eL7C8NMM7_J4Rr8aAtGyEALw_wcB

 

[Hayden]

i've used filters similar to these. you have to get specific ones for wavelength you're using. they will stop almost all visible light but will reduce some of the uv.
https://www.ebay.com/i/232899453207...kdjQvg6YcvKRxN4Y7eL7C8NMM7_J4Rr8aAtGyEALw_wcB

Thankyou mercrazy I'll definitely look at it and if they do filter 99% of visible light out then could I add more leds to compensate for the little bit of 365nm loss that the filter gives???
It's just I've seen UV lights that make things glow bright and they have next to no visible light making the effect real trippy and cool BUT I don't know

how they have done it..... maybe what you said with the filter???

Now if I do get the filter then I'll have to work out the size of the filter as I need one 40x15cm
if they even come that big haha
thankyou so much!!

 

[Mike S]

I've purchased a lot of LiteOn and Luminus 365 nm LED's for work which are used for optical inspection (probably upwards of 500 in total). They're both pretty good, but the LiteOn LED's tend to have more variation. Most produce very little visible light, however occasionally you'll get few that have a pale violet/white light. The Luminus LED's are more consistent, but also slightly more expensive.

I haven't had much luck with using UV-A bandpass filters. They knock out some of visible light, but it wasn't a significant change. Depending on where you buy them, your results may vary.

Check Digikey, Mouser or any of the other big name component suppliers for high quality UV LED's.

By the way, I don't think Cree has made a UV LED in over a decade. As a matter fact, I remember reading that they bought the die's from someone else and repackaged them. Someone can correct me if I'm wrong.

 

[Seattle Sparky]

deleted

 

[Dave_H]

Just curious, is there a cheap method of checking approximate wavelength of UV emitters, without resorting to expensive detectors/instruments? I was thinking of a series of patches of material which fluoresce at different wavelengths. At least the relative brightness between patches would give a idea; or would it likely be thrown off by the visible light? Dave

 

[Dr. Mario]

I have a blacklight flashlight, and it has Nichia NVSU233 (my profile picture is this flashlight), which is apparently top of the line as far as UV LEDs go, and it's not easy to get it - you can try asking Nichia, they could be willing to sell you some. I really like it. Too bad Cree completely stopped making them.

I also recommend buying "Wood's Glass" filter, and you can obtain some cheaply, under the "ZWB1" filter classification which you can easily find a lot of the varieties of this filter on eBay. It did really clean up the ultraviolet light very well, removing broad spectrum down to 380 - 375nm while allowing the 365nm peak light to leave (I can see the ultraviolet, so I wanted to remove the ~400 - 370nm purple light, which distracts me from really seeing any fluorescences - 365nm light looks like nasty and harsh purple hue to me).

My list of UV LED brand I could count on;
Samsung (not sure if they have 365nm version)
Nichia (which I already have)
LG
Inolux (which is also part of LG)
LEDEngin
Luminus Devices

Sent from my OnePlus 6T using Tapatalk

 

[Datman]

In 2019 I bought 5x LG 3W UV 365nm leds from led-world2007 on ebay, some ZWB2 filters and I made a UV light in a wood case. Now he sells only Cree 5W LEDs.
You have to pay attention to the heat: mount LEDs on thick aluminium and put a fan pointing at it. Use thick sandpaper to increase heat exchange aluminium surface.

 

[mercrazy]

In 2019 I bought 5x LG 3W UV 365nm leds from led-world2007 on ebay, some ZWB2 filters and I made a UV light in a wood case. Now he sells only Cree 5W LEDs.

Cree is making 5w UVs?

 

[Datman]

Not exactly

Specification
Chip Brand: Epileds

Emitted Color: Ultra Violet UV
Wavelength: 365nm/380nm/395nm/420nm

Power: 5W
DC Forward Voltage (VF): 3.8V~4.2V
DC Forward Current (IF): 350mA~1.2A
PCB Material: Copper
PCB Diameter: 20mm

Package Include:
5x 5W Ultra Violet UV High Power LED

https://www.ebay.it/itm/5pcs-5W-Ult...ght/232776528723?_trksid=p2485497.m4902.l9144

I also bought some other 365nm LEDs. They're very similar.

365nm LEDs emit a bit of visible light. I bought and mounted ZWB2 filters, but now I can say that the difference is really visible only looking at the LEDs. I could make another UV light without filters, but something is needed against dust, then I should use some plexiglass or similar, after trying for UV transparency.

 

[Datman]

Here you can see some pictures. Power is by USB-C or 5...24V (internal SMPS).
https://postimg.cc/gallery/g0Z59L0







Differences between LEDs are only in the picture, due to different angles.