What is the magical ingredient in U340 to block IR and can we all petition Hoya or Schott to triple it?

[dabateman]

Aren't they the same? If not, what is the difference?

 

I found they aren't when trying to image at 185nm.

Basically fused silica would be good for me to image very low going deep to even 150nm. Quartz cuts off in the low 200's. Why quartz lenses specifications never go below 220nm.

 

But quartz would be good for Andy as fused silica aborbs in the higher IR water bands.

 

Uv grade sapphire lens would be good for both Andy and I crazy imaging desires.

[Stefano]

Andy would probably be set with ZnSe lenses. They don't even fully transmit visible light (they don't pass blue and below), but have excellent NIR, SWIR and MWIR performance, and they also pass the first LWIR region (but he already has a thermal camera for LWIR).

[Cadmium]

Steve, thanks for sharing that old Jena information. I recently found a filter supplier in the UK that had some small samples of old UG2, UG3 and UG12 on their shelves, so I have asked for them to be made into filters for me. I was struggling to find much (or any) info on them online, so at least this covers 2 of them.

 

Jonathan, Here are a few other pages from the book that may be of interest.

 

From the JENA GLASWERK SCHOTT & JEN., MAINZ "Color Filter Glass" book (by the way, I see two copies of this book currently listed on eBay).

Page 17

 

Page 12 & 13

 

Page 14

 

Please let me know if anyone wants some other page.

[Andy Perrin]

The real problem for me is not transmission in SWIR (my ThorLabs lenses are ok there) but getting lenses with AR coatings that function from UV to SWIR, and the same for focal shift across that range which is an even bigger problem. I would not buy ZnSe because of the visible issues (unless I wanted a SWIR only lens).

[JMC]

Thanks Steve. I hadn't realised there were so many different UG glasses that have been discontinued.

[dabateman]

Jonathan,

One question I think would be interesting would be if you scanned all your quartz lenses at your minimum tolerable wavelength of your spectrometer.

I know you probably don't have a great light source. And may only be able to look at 200nm at best.

But would be interesting to see which quartz lenses fall off first.

 

[JMC]

David. It's more the light source that's the issue. For my lens transmission work I need to use a specific light source which doesn't go very low. 280nm is about the lowest I can get usable data. If I had a different light source I could get down to about 250nm with the spectrometer.

[Stefano]

If I had a different light source I could get down to about 250nm with the spectrometer.

Like a deuterium lamp?

[Cadmium]

Thanks Steve. I hadn't realised there were so many different UG glasses that have been discontinued.

Thanks Steve. I hadn't realised there were so many different UG glasses that have been discontinued.

 

I think Schott UG2A is the newest U glass they make. Not to be confused with the discontinued UG2 that you have and is shown in the graph on the previous page of this topic,

because the discontinued UG2 doesn't look that much different than UG1 at the same thickness.

NOTE: The graphs I have posted here from the book are all shown as 1mm thick, but even so.

[Cadmium]

I was just curious, so here is an overlay comparison using the new Schott UG1 and UG2A data and the old Schott UG1 and UG2 graph plots.

New and old UG1 graph plots follow each other pretty close.

New UG2A and the old UG2 don't follow the same plot.

Interestingly, the old UG12 seems to follow the new UG2A fairly close.

UG12 and UG14 might be interesting used for UV+Blue+Green stacks, AKA 'Bee Vision', such as the UG5 (U-330) 1.5mm + S9712 2mm stack.

 

[colinbm]

Water & Copper Sulfate in solution both block IR & pass near UV.

[Andy Perrin]

Water & Copper Sulfate in solution both block IR & pass near UV.

I believe someone here — Reed, I think? — actually made a liquid filter that way some time ago.

[Stefano]

And here it is: https://www.ultravioletphotography.com/content/index.php/topic/1103-a-new-uv-bandpass-filter/page__1

[Stefano]

If we could make a copper sulfate glass, it would make S8612 a thing of the past.

[dabateman]

If we could make a copper sulfate glass, it would make S8612 a thing of the past.

 

No I think S8612 is better see:

[dabateman]

That link to Reed's thread also shows the problem with quartz at the low UV end cutting off at 200nm to 230nm depending on quartz and impurities.

The fused silica goes deeper, but has the water absorbing bands. I haven't seen a fused silica lens yet. But fused silica out of china is very cheap. Much cheaper than Reed implied back in 2014 and 2015.

I can get a single element and try to build a lenses. But the optics still wouldn't be great. My pinhole was quite ugly at 185nm. Not sure if a single element fused silica lens would be better.

[Stefano]

Never tried to project an image on a wall using a magnifying lens? You get a pretty sharp image in the center, but you have strong "edge effects". That's why camera lenses are made with at least (I think) 3 elements. A big advantage using a lens is that you collectc a lot more light.

[Stefano]

 

 

No I think S8612 is better see:

I found a very promising graph here https://www.fotozones.com/live/index.php?/forums/topic/33204-cuso4-uv-filter/

[Cadmium]

I wonder what ever happened to that Copper U?

[Stefano]

Is it possible to grow some CuSO4*5H2O crystals, cut a circular slab from them, polish it and protect it from water with a quartz/fused silica filter? (water would literally "eat" that filter!).

[Cadmium]

http://adsabs.harvard.edu/full/1968PASP...80..624W

[dabateman]

Bg39 does contain copper. If its in the CuSO4 version is hard to know as only oxide data is in the MSDS.

Its also upto 10%.

[Cadmium]

You keep working on it, let me know...

Good luck.

[colinbm]

The pioneers of glass melts go back at least to the dark ages when they were making stained glass windows.

They were grinding stuff to nanometer size, by look & feel to get exact colours.

Even gold was ground to an exacting size to give a rich red glass.

'Structural Colour' is fascinating.....

[Cadmium]

Sounds like a project to me.