My Modified Olympus BHB - UV transmission

What equipment do you use? Post pictures and descriptions of your microscope(s) here!
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JMC
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Joined: Wed Mar 30, 2022 9:21 am

My Modified Olympus BHB - UV transmission

#1 Post by JMC » Fri Apr 08, 2022 1:20 pm

Here is my microscope. It's an Olympus BHB, which I've modified to allow me to do UV transmission microscopy down to about 300nm.
Figure 9 the device small.jpg
Figure 9 the device small.jpg (119.06 KiB) Viewed 2915 times
I built this originally to look at sunscreen cream emulsions. Being able to image at 313nm and 365nm allows me to see different UV filters in the creams directly.

For use in the short wavelength UV all the glass has been replaced with quartz or UV fused silica, as glass would block the light, so I changed the lenses in the microscope. It has a Lomo quartz photoeyepiece, and a Zeiss 50W mercury xenon lamp (even that needed changing as it had a glass lens in it for focusing). The condenser is an antique quartz one from Zeiss, and I typically use Zeiss Ultrafluar objectives.

I used quartz or fused silica slides and coverslips.

Images are captured using a monochrome converted Nikon d800, which has had the Bayer filter taken off, and the sensor coverglass replaced with a fused silica window.

I currently use it at 313nm, 365nm and 546nm for looking at the sunscreen emulsions, but have also tried it for diatoms. Using 313nm leads to markedly improved resolution compared to visible light.

PeteM
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Re: My Modified Olympus BHB - UV transmission

#2 Post by PeteM » Fri Apr 08, 2022 4:16 pm

Very clever - and likely an extended project finding all those UV transparent optics.

Curious what you've learned about sunscreens? Also - do you use a barrier filter before the eyepieces or just use only the camera for viewing?

Scarodactyl
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Re: My Modified Olympus BHB - UV transmission

#3 Post by Scarodactyl » Fri Apr 08, 2022 5:51 pm

Very impressive work putting this baby together!

dtsh
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Re: My Modified Olympus BHB - UV transmission

#4 Post by dtsh » Fri Apr 08, 2022 6:28 pm

That is an absolutely impressive undertaking. The effort needed to find and source all the replacement parts...
I'm also interested in hearing/seeing how it performs and what you've found.

JMC
Posts: 57
Joined: Wed Mar 30, 2022 9:21 am

Re: My Modified Olympus BHB - UV transmission

#5 Post by JMC » Sat Apr 09, 2022 8:05 am

Thanks all.

The sunscreen work is ongoing and at the moment most of specifics are confidential, as I am working with a couple of sunscreen manufacturers on it. However, if you look at a sunscreen emulsion (cream) with visible light transmission microscopy many of them contain droplets of oil suspended in a water matrix - an oil in water emulsion a bit like mayonnaise. The droplets and the water phase both look clear in visible light microscopy, as there is nothing which absorbs the light. If I then look at the sunscreen sample with 365nm I can see where the ingredients which absorb UVA are sitting in the cream as they look dark - are they in the oil phase or the water phase, if in the oil phase are they dispersed amongst all the oil droplets etc? Then, by looking at the same sample at 313nm I can see where ingredients which absorb UVB are present. How the ingredients are dispersed in the product impacts how the cream performs when it is applied, so helps the formulation designers to make better products. Also, some products suffer from crystallization of ingredients over time. Again, by look at different wavelengths in the UV this helps to determine whether these crystals are sunscreens or other components. The simplicity with this approach is that it directly images the ingredients based on their optical properties, and doesn't rely on complex staining or other analytical techniques. I have a few sample pictures which I'll put up when I get a minute.

Safety is a top priority when using this device. I always wear UV safety glasses when the lamp is on. Below the eyepieces are yellow filters which block >99.99% of the light below 400nm. Also I use a filter which blocks UV and IR on the field iris lens when using it to image in the visible region. I only look through the eyepieces when using it for visible light. For UV work, all refocusing is done using live view on the camera.

From a technical point of view it has been a real challenge, but great fun - I had no idea it would be so complex when I got into it, but as of 2020 when I started it my microscopy experience was looking down a few of them over 20 years ago when I was at Uni. However I've been working with photography for around 25 years, and UV photography for about 10 years, and without that I wouldn't have even attempted it. I also have my own spectrometer and have built equipment to measure lens transmission in the UV, and camera spectral sensitivity, and again without that I wouldn't have been able to attempt it. Finding the optics wasn't easy, and I have trawled the likes of eBay and microscope dealers. It also wasn't a cheap project (15GBP for a UV fused silica coverslip means that you learn how to clean and look after them), but as I am now using it for work it is helping to pay for it. The plan is to start publishing the work with it so I'll be starting to write more papers once I can get approval to do so.

Interestingly it has proved very good for looking at diatoms, as 313nm offers a significant improvement in resolution. Again, I'll get some sample images up to show what I mean. Currently, based on the diatom images, I think I am resolving features down to about 200nm with it, and have a resolution test target on order which will help me with trying to put some actual numbers to that.

Hobbyst46
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Re: My Modified Olympus BHB - UV transmission

#6 Post by Hobbyst46 » Sat Apr 09, 2022 1:23 pm

Applause for a very nice and focused ( :) ) project. Will doubtlessly yield practical achievements and publications.
Looking forward to see specimen photos !

I see you married an Exacta adapter to the Olympus phototube.
Which other components on the phototube ? is it afocal, with a Zeiss projection eyepiece to match the Ultrafluars ?

JMC
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Re: My Modified Olympus BHB - UV transmission

#7 Post by JMC » Sat Apr 09, 2022 1:57 pm

Added a post with a diatom image taken at 313nm - viewtopic.php?f=6&t=15303

JMC
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Re: My Modified Olympus BHB - UV transmission

#8 Post by JMC » Sat Apr 09, 2022 2:05 pm

Hobbyst46 wrote:
Sat Apr 09, 2022 1:23 pm
Applause for a very nice and focused ( :) ) project. Will doubtlessly yield practical achievements and publications.
Looking forward to see specimen photos !

I see you married an Exacta adapter to the Olympus phototube.
Which other components on the phototube ? is it afocal, with a Zeiss projection eyepiece to match the Ultrafluars ?
Thanks.

Ok, the photo eyepiece setup. I'm actually using a Lomo UV photoeyepiece (which is made of quartz), so far I have not been able to track down a Zeiss one which was designed for the Ultrafluars. That is the only lens (I don't use another camera lens). I use that adapter, as it has a good clamp for the eyepiece tube and M42 thread on the other end to allow me to easily adapt it to different cameras (and it was the second one I tried, and I liked how it was put together). I then played around with different M42 extension tubes to see which setup gave a good image. To swap between 365nm and 313nm I remove the tube and place the correct filter on top of the photoeyepiece, before putting it back together again. Not ideal, but I haven't figured out a better solution yet. I use two stacked 313nm OD4 bandpass filters from Edmunds Optics, and 2 stacked ones for 365nm as well. One 313nm didn't give enough blocking of unwanted wavelengths, which is why 2 are stacked together. I did the same for the 365nm to keep the optical path length the same when doing UV imaging to help reduce the need for refocusing.

Hobbyst46
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Re: My Modified Olympus BHB - UV transmission

#9 Post by Hobbyst46 » Sat Apr 09, 2022 2:51 pm

Interesting ! Thanks for the details.

Cristian11
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Re: My Modified Olympus BHB - UV transmission

#10 Post by Cristian11 » Wed Aug 24, 2022 8:52 pm

You are actually doing research and science with that! I envy your brains haha. Congrats!

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