Quartz coverslips really needed for UV-C microscopy?

[Lou Jost]

I've been finding that regular glass coverslips are still usable for UV-C microscopy. This seems to contradict some transmission measurements by Jonathan and others. I posted my tests on the Photomacrography forum:

 

http://www.photomacrography.net/forum/viewtopic.php?f=8&t=46607

 

I won't repeat the long posts here, but maybe a forum member here can figure out what is going on? I've checked everything to the best of my ability, but I may have missed something. If anyone can find the flaw, it would be someone on this forum.

 

If it is true that we can use regular coverslips, this makes UV-C microscopy much more practical for research, since fused silica coverslips are very very expensive and fragile, and most researchers go through lots of coverslips very quickly. Along with standard tests, I also recorded the different focus shifts as expected from different "colors" of UV light.

 

Thanks in advance.

[ulf]

Maybe you have found coverslips with a more favourable glass composition with an UV-cutoff more close to 300nm.

Then in combination with the thin thickness of the coverglass you will reach a bit further into UV and might still have at least a limited reach into UV-C that still is usable.

 

When you have the proper spectrometer equipment a transmission measurement of a flat optical component as a filter or a coverglass is very simple.

It is much better to get the information of the transmission only instead of doing a comparison involving other filters, cameras and their transmission and sensitivities, in combination of any available light source.

 

Among members here at least Jonathan and I have such tools and know how to use them.
If you want I can measure the transmission of your coverslips. Just let me know.

My measurement range for such measurements is approaching 200nm

Joathan and I have the same type of light source and our spectrometers, I think have a similar range into UV 

[Andy Perrin]

Optical properties are very very sensitive to doping with even infinitesimal amounts of contaminants or small variations in the ingredients. I think this sensitivity is even larger in the far UV (where nearly everything likes to absorb). It seems very plausible that different brands or even different batches of coverslips might vary a lot, especially since they likely don't control for it, and perhaps you found one that transmits well. I hope you can send some to Jonathan or Ulf for measurement, since that is the best way to know for sure.

 

Lou, looking at the path you are going down, it seems to me that sooner or later you are going to need to develop some UV spectroscopy skills (and acquire some equipment) unless you can find someone local who can do it for you. Otherwise you're never going to be 100% sure of anything.

[Lou Jost]

Thanks Andy and Ulf.  Actually Jonathan has already offered to test these coverslips, but it is not easy to send them from here. I can send some with friends who travel from here to Europe eventually.It would be interesting to know the transmission.

 

I have no budget for spectroscopic equipment, apart from my diffraction gratings. But careful thinking and experiment should also be able to reveal wavelengths. I think that for a simple quartz lens the focus diffferential is a direct measurement of the wavelength dfference, so maybe I can calibrate that. Several of us have noted on a recent thread that this difference is surprisingly large.

 

Also the jet-black completely opaque glassware in my photos seems to me to be proof that most of the light I was imaging  is UV-C.