OFM Optics for Metallurgy Applications (& Epi-illumination Kohler Design)

Hi there! I’ve seen a couple of people ask whether the OFM can be applied to metallurgy applications. Over the covid break I’ve been spending most of my time looking at exactly this so I thought I’d share. Essentially the answer is yes but it’s limited in it’s capabilities at very high magnification, which I suspect is due to the simplistic illumination method. Another issue is that metallurgical objectives can be on the expensive side with the cheapest ones coming in at around £100.

I’ve compiled an imgur album of the work I’ve done showing off the OFM optics + reflection illumination module in action on a (slightly scratched up) polished sample. I’ve also developed a small 3 axis motion system based on aluminium extrusion profiles (the ones that a lot of 3d printers use for structural components) due to a large scope of travel being desirable for my particular application. OFM For Metallurgy Application.

A (very) high resolution image of a scan test with a 15mm travel scan can be seen in the following link. Due to uneven illumination and the pi camera’s love for a vignette effect it requires some flat field correction in imagej before processing to get a good stitch.

I’ve also designed a primitive kohler illumination arm for reflection microscopy which I’m about to begin testing. Renderings of the design are in the imgur album. If anyone wants to improve on my design using OpenSCAD that would probably be much better.

I also just want to thank all the guys that have contributed to the development if the scope, it’s truly awesome and incredibly versatile!

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That looks great! I’ll be particularly interested in your results from the reflection kohler illumination arm. I’ve been investigating using reflection illumination for flourescent imaging with the standard OFM but we were halted.

It needs improving to create a more even illumination. However, the standard OFM has quite a tight space for reflection illumination, so it will be good to learn what worked well from your design and what improvements I can squeeze in for use in the standard OFM (when we can get back to the lab!)