Bonse-Hart USAXS on a shoestring budget

As some of you might know, I have long been a fan of the Bonse-Hart type ultra-small-angle scattering machines [1]. These instruments allow us to measure to extremely small angles while not taking up more space than a big microwave (ok, maybe just a little more). These extremely small angles let us measure anything from nanometer-scale all the way up to micron scale, neatly extending the range of your standard run-of-the-mill SAXS machine. To sum up this paragraph: I want one.

As some of you will also know, I have a lot of comments on the machines of others. I do not appreciate much of the control software of many of the machines, some of the detector options are more pain than fun, some safety interlocks will damage your generator if you so much as look at them wrong, and a fair few scatter so much themselves that measuring a sample becomes a game of “where-is-my-signal-Waldo”. Secondly, there are no off-the-shelf Bonse-Hart instruments yet (they will be happy to build you one for the right price, though).

We have a normal pinhole-SAXS instrument in the lab which is reasonably problem-free (though I still grumble about its safety interlock choices and that damn control software messing up the nice detector images), but as most common pinhole-SAXS instruments, that machine measures only sample features up to about 30 nm. Many of our samples, though, also show many interesting features beyond that.

So I wanted to realize two of my dreams: 1) get a Bonse-Hart camera to extend that range, and 2) build it myself so I have nothing to complain about (except to myself). As you can expect, the problems are: 1) no money (well, “only” about 15 kEuro), and 2) no experience.

Over the course of the last year, I have been spending some of my remaining time at work in the workshop, trying to build an instrument for a spare X-ray generator. It is, by now, nearly done. Let me show you how far it has come.

A short movie of me in the workshop making things:

And then, a year after I set off on this project, there is some progress to show!

The instrument now looks like this, with a small collimation section in lieu of some parallelizing optics, followed by the high-precision rotations with some graciously borrowed test-crystals on them:

An overview of the bonse-hart instrument in place.

An overview of the bonse-hart instrument in place.

A close-up of the two rotations show the crystals on top of a slew of rotations and translations, all manual:

The two stacks of rotations and translations on top of the high-precision rotations, topped off by two double-bounce crystals (for testing).

The two stacks of rotations and translations on top of the high-precision rotations, topped off by two double-bounce crystals (for testing).

So as you can see, I had fun building this instrument, and soon it will be put to the test (as soon as I get some suitable shielding in place so I do not irradiate myself). I can’t wait to see the first results!

Naturally, there is still a lot to be done, it is designed for a vacuum box, which is not yet in place (try without first). There are two detectors, one of which is a PIN-diode variant which I have yet to assemble and test. Lastly, I have the task of integrating all equipment with some software, and since I do not have money for SPEC, it will have to be some custom Python code. With just a couple of motors, however, this should be easy in theory…

Best of all, though, if all goes well, the technical drawings for this instrument will be published under a Creative-Commons attribution (sharealike?) license (which means this). This would allow any of you to make a copy or improvement on this design quickly and efficiently! Just take the drawings to your friendly neighbourhood workshop people and have them build you the parts!

As always, looking forward to your comments!

[1] Bonse, U. and Hart, M., Zeitschrift für Physik, 189 (1966), 151–162

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1 Trackback to "Bonse-Hart USAXS on a shoestring budget"

  1. on 2013/04/15 at 12:04