A Leeuwenhoek microscope project

I don't view the transition to be steep where it matters - it's rather gentle, really. You can use a larger ball-end mill to make it more gradual if desired. You could round off the shoulders, too, but I don't see that as being a big source of problems.

But yes, you would want to polish out any machining marks in the troughs. I should have polished the edges of the strip before the milling, too, but it was just a test.

Even what I did so far was decent (light sanding with 400 grit using paper wrapped around a rod). But with hand-sanding it's almost impossible not to thin the edges of the hinge more than the center. Maybe a jig could help, but it still wouldn't be perfect.

That idea about thinning an already thin strip - have you tried it? I wouldn't have confidence that it would work out well for similar reasons.

The big take-away for me is that this metal, cold-worked 510 phosphor bronze in "spring temper," thinned to ~0.003", still does not have the right sort of spring to it, and is certainly too fragile, to be used in a practical clock pendulum.

Because I'm a romantic, I might still try to build it into a pendulum. But I'd want to compare it to an alternative, such as my knife-edge pivots, e.g. to see which results in the best Q.

I guess the other point to remember is that there are thousands of pendulum suspension springs flexing 86400 times a day for decades clamped between square cornered chops, and how often do they actually fail?

Build everything else and save the thinning for absolute last, then gingerly hang it. It should be good then, and possibly better - I don't know.

At least one world-beating clock used this technique, so it's worth a look.

Edited By S K on 06/06/2023 18:34:03

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For this particular application, no … but the general method, yes

MichaelG.

In a bid to get this thread back closer to microscopy … here’s an interesting freebie from the RMS:

**LINK**

https://www.rms.org.uk/resource/nature-s-smallest-glasshouses-visible-from-space.html

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Fig.18 might encourage amateur constructors … although I am rather concerned by its description as “a simple, but remarkably effective, miniature, compound microscope” since, to the best of my knowledge it is not a compound microscope 

MichaelG.

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Edit: __ See also https://microscope-antiques.com/algen.html

Edited By Michael Gilligan on 07/06/2023 08:57:34

… and a little more detail here: **LINK**

http://microscopist.net/ThumE.html

MichaelG.

Diatoms are fascinating!

I'm trying to decide on a next project. I could make a Mk II version of this, or else maybe a compound microscope.

As with my previous gravity pendulum project, I have an interest in replicating classic scientific experiments. A few ideas might include be the Millikan oil drop experiment or Young's double-slit experiment.

There's an interesting variation of the double-slit experiment called a Mach-Zehnder interferometer. Instead of using two slits, photons are split across two paths by a half-mirror. It's important to not fall into the presumption that individual photons are traveling through one path or the other. In fact, they are traveling through both paths simultaneously in a "superposition" of the two paths, even though the two paths may be very far apart.

Other mirrors are then used to redirect the two paths back together, where they encounter another half-mirror. If light was considered to be particles, you should see half the light exiting the second half-mirror one way, and half the other. But if the photons are waves, interference between the single photon traveling in superposition down the two paths should occur. If set up right, a detector at one exit of the second half-mirror should show all photons exiting with probability 1 (due to constructive interference), while the other should show none (due to destructive interference). Indeed, that is what is seen.

But what if you destroyed the superposition of two paths by blocking one path (equivalent to blocking one slit in the double-slit experiment)? Then, there is only one path left, and hence no possibility of interference anymore. Both exits of the second half-mirror should now show photons exiting, with probability 1/2 for both. This experiment thus demonstrates the wave/particle duality in the same way as the double-slit experiment, but by using two discrete paths rather than a field of paths.

The next step is called the "quantum eraser" experiment. In this, you can apparently measure the path that a photon takes, thereby destroying its ability to interfere with itself, but then erase the measurement and allow it to interfere with itself again. This experiment is difficult for an amateur to do (properly, though a simpler version is more accessible) since it requires entanglement, not just spatial superposition. It's normally done via a special "down-conversion" crystal - one that produces two entangled photons of lower wavelength from one input photon. These crystals are available, but are quite expensive. Particularly sensitive and expensive avalanche photodetectors, etc., would also be needed, since you want to detect individual photons and not just "light."

The step after that is the "delayed choice quantum eraser" experiment. In this, you attempt to change the apparatus after a photon is already traveling through it (such as if you measure a state or block a path, etc.). The photon must then - seemingly, but not really - go back in time to change its state or path in response. This experiment is endlessly debated by youtubers and authors who are into woo-woo physics. Unfortunately, because light travels so fast, this experiment is extremely difficult to do.

Any other ideas?

Edited By S K on 07/06/2023 16:30:30

I am making plans to build an interferometer (e.g. the Mach-Zehnder type), but I think that's outside the scope of this forum. A Mk-II or compound microscope should also be coming, eventually. But for the immediate here and now, I'll probably return to pendulums, i.e. for a Arduinome-type clock.

As a coda to this thread, though: I had a couple of spare lenses and turned them into a pair of pretty awesome magnifying glasses. They are antireflective-coated two-element achromats. The larger one is 50mm diameter with a 200mm focal length, and the smaller one is 30mm diameter with a 150mm focal length. They are a little higher power than the nominal 250mm of a standard magnifying glass. They are super clear and sharp, and so much better than my old scratched up plastic one! I've found them to be very handy in my hobby room. 🙂

Edited By S K on 10/06/2023 18:42:39

Edited By S K on 10/06/2023 18:43:27