[UVC Safety Warning] Huge fast 254nm photolithography lens

[Lou Jost]

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.

 

---

 

 

It is hard to find lenses made specifically for UV-C. But for some years, 254nm was the main wavelength used for printing transistor and microprocessor circuits on silicon wafers. These were made to have perfectly flat fields, large apertures in order to avoid diffraction, and extremely high resolution. To achieve the highest possible resolution, these lenses are optimized for a single wavelength. These lenses could cost hundreds of thousands of dollars (their more modern replacements cost millions). They were among the most perfect lenses of their time, and they could use very exotic materials.

 

Sometimes these come up for sale on eBay or industrial salvage sites. That's how I got this Tamarack Scientific 254nm 1/5x reduction lens. The lens alone weights 10kg!

 

[Lou Jost]

I attached it to a full spectrum Sony A7R and tested it last night. It is optimized for m=1/5. For a 35mm sensor, the FOV would be about 17.5cm. I used a 254nm light source with very small non-target emissions at longer wavelengths. Depth of field is tiny, and there is no aperture so it can't be stopped down. I imagine the image I got with this equipment and filter set (a short-pass UV filter from image-labs) was from 365nm light, so not as sharp as it could be. But still quite sharp, at least the parts that are in focus-- the flowers. Here is the whole image (focus is on the flowers) and a crop of the flowers. Note that the flowers are near the edge of the frame, so their sharpness is especially noteworthy.

 

 

 

 

 

Next is a 100% crop, and then a 2x enlargement of the crop. It is about as sharp as it could be for a Bayer-filtered image. This would surely be much sharper if I had a sensor and filter apt for 254nm.

 

[Lou Jost]

The lens may be optimized to shoot through a quartz pane, either in front or behind. But I can't find any info on how it was used. Also, the front filter I used was thick and the rim caused vignetting.

[colinbm]

What a great lens.

[Lou Jost]

Thanks Colin. It should be usable in reverse at 5x as well. Reversed, it would have very long working distance for a  5x objective..

[Andy Perrin]

A very nice find! Yes, probably 365nm sounds like a reasonable guess. Efforts are ongoing to get good UV-C pics around here, as discussed elsewhere yesterday. Do tell us if you decide to highlighter a debayered sensor or something. (I think Jonathan's issue with the uneven thickness of the highlighter marks could be adjusted for using a "flatfield correction" -- subtracting off the uneven background essentially.)

 

What RAW converter did you use? I find the the Raw Photo Processor 64 (RPP64) on Mac is the sharpest with fewest artifacts. The grain in your images looks a little odd.

[lukaszgryglicki]

I would say WOW and I really wonder what it can image at mercury line 254nm...

As already posted elsewhere I'm close to get something at 254nm (or not), my 2 current obstacles are:

- Filtering out anything above 260nm.

- Possibility than sensor sensitivity is too low to record anything.

 

[Andy Perrin]

Lukas didn't you buy one of the RUVIS Sirchie devices? Or was that someone else? Those can definitely do 254, since that's their design wavelength. If you have one, definitely try that first so you have a baseline to work from. 

-

 

By the way, Lou, you need to add the required safety warning at the top of the original post for this thread. All UV-C lit photographs need a warning label about the safety requirements. One warning at top of the thread is enough. Example here:

 

[lukaszgryglicki]

21 minutes ago, Andy Perrin said:

Lukas didn't you buy one of the RUVIS Sirchie devices

No, I don't even know what it is...

[Andy Perrin]

Like this one

 

https://usermanual.wiki/Document/03ruvis.475838047.pdf

 

Several of us got them, they do seem to work. Easiest way to see UV-C that I know of. And the filter inside has amazing blocking. 

[lukaszgryglicki]

Looking nice, but I was never hunting for a ready device like this, I'm rather a photography fan, and I want (not sure if possible) to record UV-C on a large sensor (44x33mm in my case, MF in digital world while just a tiny bit larger than normal 35mm film frame and shame even to 645 in film world).

 

I just wonder now.... hmm never thought about this....

What if I put UV-Nikkor on my Nikon F4 body and try to record UV-C on film ??

But how to guess exposure, I don't need to block IR leaks so maybe I could get soime useful filtering?

 

[JMC]

Lou, nice lens. If you are wondering if this picking up UVA lines if you have a glass microscope slide or even something like a glass vase or just a drinking glass, take a photo of it with your 254nm mercury lamp behind it. If it is UVA then it'll be pretty much transparent. UVB or shorter it'll be black.

[lukaszgryglicki]

Exactly, my attempts on UV-B show that all glasses are almost black and my 3-glasses window is TOTALLY black even with 12800 ISO, f=4.5 and 5min exposure.

 

[colinbm]

7 minutes ago, lukaszgryglicki said:

Exactly, my attempts on UV-B show that all glasses are almost black and my 3-glasses window is TOTALLY black even with 12800 ISO, f=4.5 and 5min exposure.

 

[dabateman]

At 10kg, it might be hard to run around through the garden with it to take flower shots. But excellent find.  That looks like an amazing lens that should be diffraction limited by design.  

[Lou Jost]

3 hours ago, JMC said:

Lou, nice lens. If you are wondering if this picking up UVA lines if you have a glass microscope slide or even something like a glass vase or just a drinking glass, take a photo of it with your 254nm mercury lamp behind it. If it is UVA then it'll be pretty much transparent. UVB or shorter it'll be black.

Good point. Will try that at next opportunity.

[Lou Jost]

7 hours ago, Andy Perrin said:

By the way, Lou, you need to add the required safety warning at the top of the original post for this thread. All UV-C lit photographs need a warning label about the safety requirements. One warning at top of the thread is enough. Example here:

 

 Done, thanks

 

How much do those Sirchie cameras + filter cost?   Edit: I just found a price. Never mind. Far above my budget.

[JMC]

Lou, those of us who got the Sirchie cameras and lenses got them when a few cheap ones appeared on ebay. 

[lukaszgryglicki]

I see that would be better setup than trying to do this with MF sensor, but still, I want to get UV-C on MF if possible, UV-B is already there IMHO and I can make it outside on a tripod, which I'm planning to do once the weather is good and I have time for a long long walk throught the city.

[Andy Perrin]

2 hours ago, Lou Jost said:

 Done, thanks

 

How much do those Sirchie cameras + filter cost?   Edit: I just found a price. Never mind. Far above my budget.

About $1000 on ebay right now. Jonathan what did we pay? I don’t recall but it was in the same ballpark I thought. 
 

https://www.ebay.com/itm/334639222331?hash=item4dea0d4e3b:g:PVkAAOSweQxjfrcS&amdata=enc%3AAQAHAAAAoGPI8PoBqWwT5Y4Lg6Pruq9NvDYLujJt6v3%2BZhEW7gt0d00WIWHTQ0ySamDjdgGpylcNjvGtjzn%2Fb3Io6vh8736Oaz8rB%2BynV8rYdEHYQ%2BLitqKQ1AeItb7yICSebLqP8ftY%2F395NVhopdAxzYVcwl1%2FSSR877OT2dNqpaOuh9QgFWAUII5OlqssGhDq5eZB5cHV1uhy7PEzmCeGBqNyjCo%3D|tkp%3ABk9SR4apjtunYQ

[JMC]

I seem to remember it wad between 600 and 1000usd depending on the specifics of each device.

[Lou Jost]

10 hours ago, JMC said:

I seem to remember it wad between 600 and 1000usd depending on the specifics of each device.

That's much better! Thanks

Edit- It is already gone...

[Andy Perrin]

Yes, probably because I posted it here. But, if you search eBay there are probably more. They have been coming up pretty regularly in that price range. Even if not, just watch eBay for them and it won’t take all that long from what I’ve seen. 
 

If you could find that lens, you won’t have trouble finding a used Krimesite imager.

[Lou Jost]

7 hours ago, Andy Perrin said:

If you could find that lens, you won’t have trouble finding a used Krimesite imager.

He heh...

 

Jonathan, it looks like you use your superconverted D850 instead of the Sirchie for most of your work. I guess that this is because it is much better?

[JMC]

33 minutes ago, Lou Jost said:

He heh...

 

Jonathan, it looks like you use your superconverted D850 instead of the Sirchie for most of your work. I guess that this is because it is much better?

Yes, I used the monochrome converted d850 for my 254nm imaging. However my new little machine vision camera with its Sony IMX487 sensor will be taking over that job on the microscope.