UV LED for fungus treatment?

[jonathan]

I see those super-bright LED torches now include a UV mode (there's a separate UV LED), they say a wavelength of 395nm (probably taken from the LED spec sheet so could be accurate).  Any idea if this sort of UV is useful on glass surfaces affected by fungus?  If so, what kind of exposure would be required?  I suppose the torches should last a good few hours on a single battery charge.  Also, I'm sceptical on the safety of UV torches being waved about generally, if they're harmful to eyes and skin then surely they wouldn't be allowed to be sold in European countries, but if they're not harmful then I'm wondering if they're too weak to be effective against fungus.

[DaveL59]

I bought these back in 2019
https://www.amazon.co.uk/gp/product/B01MS5L3EG/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1

Still working and haven't needed to replace the bulbs as yet. I set it all up inside a cardboard box and close that before powering up specifically so you can't look directly at the UV source and damage your eyesight. I generally run the max duration on the timer and repeat a few times.

Edited September 27, 2020 by DaveL59

[jonathan]

19 minutes ago, DaveL59 said:

I bought these back in 2019
https://www.amazon.co.uk/gp/product/B01MS5L3EG/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1

Still working and haven't needed to replace the bulbs as yet. I set it all up inside a cardboard box and close that before powering up specifically so you can't look directly at the UV source and damage your eyesight. I generally run the max duration on the timer and repeat a few times.

Very interesting!  I never knew such a thing existed.  So you run these for two or three hours at your eyepieces in the box, do you point the glass surfaces at the lights or just lay them flat?  I suppose one could put tin foil inside the box to get the maximum effect.

[DaveL59]

I've used them mainly for binos as I have a fair collection of them dating from 60-70s and a couple back to 20s, but in essence I lay things out so that the UV bulb is in-line with the optical path and run say 3x 1 hour cycles. It's more convenient than trying to sun them, especially with curious kitties in the house and if they've been dismantled to overhaul it'd be a nightmare to track down bits that have been played with. With 30+ binos you can't really get them all out for use frequently enough so they get enough exposure to the sun, hence obtaining a UV source. I do of course tend to give them a thorough clean and often dismantle/part overhaul in the process but long term storage it makes some sense to have a means of treating them just in case.

The scope eyepieces so far haven't needed any such treatments, but then I've stripped and cleaned the older ones as I get them but I do plan on giving them a zap every couple months.

OTA's I have used the light once so far when first acquired, reflectors being easy as you can slip the light in the end of the tube and let it run, the frac's need a bit more care so you don't hit the lens of course.

[wulfrun]

Not sure a UV torch or LED-based item will work but it could be worth a try. I know things like water-sterilisation stuff uses UV-C which is absolutely NOT eye-safe. I'd assume you need something along those lines to kill fungus. LEDs don't usually go down to UV-C wavelengths, except possibly the expensive commercial stuff. You can get UV-C fluorescent tubes easily enough though, although they come with a warning not to expose your skin or eyes. I have a 365nm 3W UV torch, but again you are warned not look into the beam. It's not very bright, visually, and that's the issue - it doesn't give a visual clue that it's actually quite powerful.

Edit - just noticed the shoe-sanitisers claim 265nm, that ought to work if the claim is true.

Edited September 27, 2020 by wulfrun
Updated

[Mick J]

Interesting idea, I see eBay has a China supplier of bulbs and UK supplier of the full kit half the price of Amazon, could not resist 😊