Quartz Lens/UV LED's for POP Projection Printing?

[Drew Wiley]

Durst L184 UV conversions were once offered by Jens at Durst Pro. I don't know how many he sold, but there were all kinds of heat issues. For that kind of thing you really need a stainless steel water jacket cooling system around the head. Huge pulsed xenon commercial units also existed for sake of the printing trade. Very expensive. Somewhere in my old literature heap I still have an ad for one. It would probably cost $150,000 to make today. An ancient carbon arc enlarger is still being used for the Fresson process in France.

[Jim Andrada]

IIRC movie theatre 35mm film projectors used to use carbon arc light sources.

[John Layton]

Lots of heat keeps creeping into this discussion...so I must repeat myself: what I am proposing here is to utilize a quartz enlarging lens, which would maximize the passage of UV light, which could very well allow use of a much cooler UV light source (LED's), especially in light of advancements in UV LED technology - allowing the prospect of creating alt-process works such as PT, PD, Albumen, etc. by enlargement, logistically feasible.

...and while I don't know much about quartz optics except that Hasselblad created one awhile back, nor do I know about how this (quartz optic) technology could be utilized to create optics for projection enlarging, my guess is that a feasibility study could be done now with one of those Hasselblad UV lenses and an array of UV LED's. And even if that particular lens design may not lend itself to projection enlarging, it could still be utilized for such testing. Agreed?

[Tin Can]

I have many

UV 365 50 watt

My for my Alt

They now have powerful 365 flashlights'

https://www.amazon.com/Everbeam-Blac...3d670b6bc&th=1

[John Layton]

Zeiss 105mm UV Sonnar:

https://www.zeiss.com/content/dam/co...r-43105-en.pdf

[Drew Wiley]

A Sonnar is a taking lens that probably wouldn't be all that great in enlarger repro ranges. The question is just how much UV needs to get through and at what exact wavelength per specific processes. You can hook up with Sandy King on that question. He's tested the variables. The enlarger head diffusion system and carrier glass are going to factor, and not just the enlarging lens - and those other components certainly aren't going to be quartz! An EL Nikkor enlarger lens should be fine, given the fact that it passes more UV than most enlarging lenses, and that you'll need considerably more UV output anyway to overwhelm the various glasses above there anyway.

[Mark J]

Most enlarging lenses will pass UV down to 380nm and will be fairly well corrected at that point.
If you want more UV and power one logical step is mercury vapour which has a strong emission at 365nm. I would have to check where Xenon emits. However any of this will require a UV-specific lens.

[Drew Wiley]

There's a reason UV enlargers are rare, and also why UV contact printing from already enlarged second generation negatives is so common.

[MartinP]

A while ago we had a problem at work involving a mercury vapour light-source that was no longer supported. There is an optical-contractor who solves that sort of problem for us (one company service is metal-film lithography for special purposes). The result was a single UV led, a doublet quartz lens and an atmel chip to control exposure, coolling etc. I think the UV was a shorter wavelrngth than you would need (around 340nm for the photo-resist). The quartz lenses were from either Edmunds or ThorLabs as a stock item, so they weren't specially made, but there are some sorts of glass that have a reasonable UV-transmission for this wavelength and you might not really, really need to use quartz if you can use a longer exposure time. The parts assembly was only a couple of thousand in total, excluding machining a new housing.

Bear in mind that this was a 'simple', evenly-illuminated light-source, as we make our products by masking rather than projection. It is unlikely that you would be able to use this for projecting a negative with much resolution.

[Mal Paso]

My current enlarger has a 30 printing watts LED head and at low power it's almost too much. I think a UV LED head is possible given you devote most of the energy to UV and eliminate almost all the heat. On my enlarger even with the white LEDs on, green and blue at full power, 53 watts, the negative stage never gets warm. There's no IR. I've burned plates and negs with arc and it's mostly smoke and flame with a little UV mixed in. Like the tungsten bulb is 95% heat 5% light.