Excimer focussing lens

[ulf]

I cannot judge if this is something worth testing, but it sounds interesting.

 

Likely it is optimised for close-up.

 

https://www.ebay.com/itm/154456142976

https://www.global-optosigma.com/en_jp/Catalogs/gno/?from=page&pnoname=ETL%2FEDL%2FNEDL&ccode=W3082&dcode=&gnoname=ETL-30-80P

[Stefano]

Looks interesting. Some members would make good use of this lens.

[Andy Perrin]

I'm very tempted, but I have a quartz lens already that will do alright for UVB/UVC imaging. This is probably better-corrected than mine, though...

[nfoto]

Obviously quickly snapped up by someone - a UVP member perhaps? (not me)

[dabateman]

I'm very tempted, but I have a quartz lens already that will do alright for UVB/UVC imaging. This is probably better-corrected than mine, though...

 

Actually our 60mm kss lens is excellent at and optimized for 255nm. Its better than my UAT there. At 255nm its the ssme as visible without much focus shift. So its odd to handle.

 

I didn't jump on this. Just saw it now. But interesting that its optimized for subjects at infinity. Not designed well for macro or close up, which is my style.

[eye4invisible]

Seems to be a fair amount of glow on the sample UVB shot on the ebay listing. Looks better for IR.

[Andy Perrin]

Seems to be a fair amount of glow on the sample UVB shot on the ebay listing. Looks better for IR.

I think you're not necessarily drawing the right conclusions -- the UVB shot seems to be made through an image intensifier tube (hence the green), which has its own artifacts, so it may not be the lens.

[JMC]

Er, yes, I bought this. Not too often that interesting stuff comes up for sale in the UK (so, no import fees) and I thought this might be useful for a project. The seller mentioned that they do a lot of UVB photography so I told them about the forum (in case they weren't aware of it already).

[Stefano]

Jonathan, it will be interesting to see what you will do with it.

[JMC]

Thanks Stefano. Yes I hope do a comparison of the 80mm plano convex, the 79mm aspheric and this 80mm excimer lens at some point.

[ulf]

All of those lenses will suffer from chromatic aberration as built with only one type of lens-material, there cannot be any chromatic correction.

The refractive index (dispersion) of FS changes rather quickly in UV:

 

It is the usage of different material types that mainly makes it possible to correct for chromatic aberrations.

Images illuminated by narrow band light sources will be OK.

[JMC]

Yeah, if I use these for imaging, I'll probably end up doing monochromatic work with them.

[dabateman]

Thanks Stefano. Yes I hope do a comparison of the 80mm plano convex, the 79mm aspheric and this 80mm excimer lens at some point.

 

Excellent I have something to look forward to. I am genuinely curious how that turns out. I have Bicx and Plcx single fused silica elements of even the same focal length, but never directly compared them to each other. I also got a couple concave elements, which aren't as useful. Although one does work well with my ball lens to increase the back focus distance.

 

I was thinking I should figure out what focal length the SvBony focal reducer is (maybe roughly 100mm), as its a positive meniscus single element and compare it with the others. But it can only see to 300nm, so UVB only.

 

[Stefano]

David, did you find a nice combination with all the experiments you did? It seems you have a lot of lenses, lots of combinations to try. Trying to copy a simple design can probably give you a decent lens, at least partially corrected. I only have car headlight lenses (they are not good for imaging, but do reach deep) and a magnifying glass.

[JMC]

Bit of an update. Thorlabs have some thread adapters to allow me to fit this to my lens setup so I've ordered two to allow me to mount it.

 

Spoke with the manufacturer and apparently this one is a triplet (the spec sheet for the range says the lenses are either 2 or 3 element but doesn't specify which one is which).