Update on UV microscope build

[JMC]

Over the past year I've been working on a bit of a side project - learning about microscopy and building a UV transmission microscope. The goal was to build a transmission microscope which could be used down to and below 300nm.

 

When I started on this project I had no idea what how complicated it would be. Lenses in the body of the microscope needed changing for UV fused silica, I made a UV condenser at one point from a half ball lens before being able to get some proper quartz condensers, the light source needed an internal lens removing, in the binocular head a prism needed cutting in half and a fused silica block had to be made to the right size to replace the glass part. This list went on and on. There's a bit of an update on the background to the build here - https://jmcscientifi...-silica-optics/

 

Recently I put everything together and tried it out. The test subject was a sunscreen cream which is an oil in water emulsion (like mayonnaise) and only contained a UVB absorbing component in the oil phase. This was imaged in visible light, at 365nm and 313nm and gave the following images.

 

Visible light

 

365nm

 

313nm

 

The big circular feature in the middle of the image is an air bubble in the sunscreen formulation. Around it is a dense structure of oil droplets in a water based continuous phase.

 

The visible and UVA region look similar (as should be expected). The interesting parts of the image are the light regions to the top and bottom right of the air bubble. When imaged in UVB, these go from looking lighter than the surroundings to looking darker, and I suspect these are more oil rich than their surroundings. As the oil has the UVB absorbing component they should be darker.

 

There's a summary of the work here - https://jmcscientifi...mages-it-works/

 

As it stands at the moment I can image down to 313nm. The microscope itself would be good down to about 250nm but this would require different light sources and camera as even at 313nm it is at the limit of my cameras sensitivity (and blocking capability of my filters).

[Stefano]

Very nice work. You even had to change some lenses and make it still working, which I guess isn't as easy as it sounds.

 

I already know something you can image in the future: https://www.ultravioletphotography.com/content/index.php/topic/4095-microscopy-of-a-monochrome-converted-camera-sensor

[dabateman]

Super cool. Very interesting approach.

I just finished building my own taking a completely different approach.

I have a table with a 70mm x 70mm hole. I shine up whatever light source I want. I use a dimmer switch for LED sources. I have the light housing in a furnace adapter to shield the light and direct it straight up to the table hole.

My hole is inset in 100 x 100mm groove. So I can stack zwb3 or zwb1 filters over the light. Thus using 9mm zwb1 and UVB light, hoping to isolate mostly the 313nm wavelength, as 9mm zwb1 is mostly a 330nm peak.

For 254nm I will be using germacidal bulb with 9mm Zwb3 to block all visible light.

I have a 3mm x 150mm x 100mm zwb3 plate that I will hold samples on, which is on two rails to adjust one visual axis.

 

My camera is positioned above on tripod with fine rails for z axis (up and down) and left and right axis. I have to be super careful with adjustments. But its doable.

I have various lenses to play with. Lucky one of my Chinese 2x objectives can see UVB. I also got a really cheap Milar 50mm f4.5 lenses capable of 10x and might see UVB. Still need to test it thoroughly.

I also need to test my fused silica lenses.

 

I am hoping to see some fun UVC induced UV transmission in various samples.