The above landscape is about a quarter inch wide.
This is industrial macro photography. Which I didn’t know existed until I needed to do on my job recently.
This is why I had the opportunity to learn how to do macrophotography with a microscope objective. In this case, I had to test an epoxy bond and evaluate the results.
We had an ongoing crisis of sorts: one of the supports for the Tzec Maun Foundation one-meter mirror had come off. We had made multiple attempts to reattach it, but they did not hold. So suddenly my job for several months has been to learn every thing possible about aerospace epoxies, because that is what is used when you want to support a 600lb mirror on 12 wires.
Yeah, wires: the mirror is supported by tiny rods that are connected on one end to a puck that is epoxied to the mirror back, and on the other end by a flexure, a complex winding mess of modern metal work that is both stiff and flexible at the same time.
To sum it up as simply as I can: the trick with pucks, wires, and flexures is to make them extremely stiff in one direction—the direction where force gets applied. This is how you get stiff where it’s needed, and flexible where that’s needed.
Ignoring the deep engineering there, the one thing you have to be able to do is to glue those damn pucks to the back of the mirror. We tried a series of such epoxies, but they were failing to stick. I spent weeks digging into it, and learned that the key to success is preparing a surface to be bonded.
Another long story made short: those atoms at the surface that you want to bond to? They have to be raw, because raw makes them energetic and eager to attach to an epoxy. Time is your enemy: air can bring contaminants, and those eager atoms snap them up like crazy, weakening the bond. Solvents can be your friend, but which ones? (A rathole of polar and non-polar solvents with considerations around atomic structure of molecules (!) to figure out what would attach contaminants the best.)
What side of abrasive? What method, what kind, what hardness, and how do you clean off the dust without further contamination? A maze of wicked proportion, it was, and thus the weeks rolled by as I read research papers (turns out that aerospace people don’t have blogs or join discussion groups; they write papers), contacted experts that I couldn’t afford to pay but who were all a bit helpful, and otherwise tried to collect the expertise about high-end bonding. What a ride! I love that sort of thing.
In the end, I put together a local team of non-experts and got them trained (it’s COVID; I wouldn’t be traveling to New Mexico to do the work). Also a fun ride; people can be the best in an emergency.
Back to photography: along the way, I had to learn this art of “extreme macrophotography.” I picked up some cheap microscope objectives, as well as an industrial-grade one from Mitutoyo. Wowser.
I tested on my workbench at home; the people in New Mexico did test abrasions and test solvent application over and over and sent samples of the various methods and chemical and techniques as bonded pairs of materials with a few likely-seeming epoxies. But we still struggled, until I found a somewhat obscure epoxy referenced in one of those papers that had everything we needed, including the ability to control a bondline thickness of a little over a tenth of a millimeter—it turns out that, for what we wanted, we needed an extremely precise, thin, layer of epoxy. It’s done with glass beads of a specific diameter embedded in the epoxy. OMG, I can’t tell you how many times I thought we had turned the corner only to run into another dead end. But this was it, as it turned out.
These photos are the proof. I used an extremely sharp and hard steel chisel to do a wedge test: try to drive the two sides (glass, steel) apart and see what happens. Since the front of the wedge is very sharp, and I was using a 16oz. hammer, I was able to apply a very large force to that very thin epoxy layer—on the order of several thousands pounds per square inch. The failure was explosive, shards everywhere. The photos show deformation of metal, shattering of glass, tearing of epoxy. The epoxy was so strong that it tore the metal and shattered the glass rather than let go (adhesive strength) or break easily (cohesive strength). We had a winner after months of learning and trying. What a great feeling. :)
But these photos are more than a reward for the work and discovery. They are beautiful miniature landscapes, pictures of a world that my own eyes cannot see unaided. What a treat to explore like this!