The ABC’s of AMO Physics

Over at Confused at a Higher Level, Melissa offers an alphabetical list of essential supplies for a condensed matter experimentalist at a small college. This is a fun idea for back-to-school time, so I’ll steal it, and offer the following alphabetical list of essentials for Atomic, Molecular, and Optical physics at a small college, kind of a condensed version of the three part series I did a few weeks ago.

A is for Acousto-optic modulator This is a device that uses sound waves in a crystal to deflect light and shift its frequency. It’s essential for rapid control of laser properties.

B is for Beamsplitter As the name suggests, this splits a beam of light into two. they can be polarizing or non-polarizing, and are obviously essential if you need to do multiple things with one laser.

C is for ConFlat vacuum hardware These things are essentially a stainless steel baby bottle, and are needed to contain the atoms you want to work with, and exclude the ones you don’t.

D is for Diode Lasers They’re flaky, but cheap and tunable.

E is for Epoxy A surprising amount of high-tech scientific apparatus is actually held together with five-minute epoxy.

F is for Fiber optics These are incredibly useful for getting light where you need it, and making sure that it won’t be too badly affected by small changes in laser alignment. They’re a huge pain in the ass to get set up the first time, but once they’re in place, they’re really useful.

G is for Gas bottles Even if you’re not running a system like mine where the atoms I cool start out as a gas, you’ll probably have a few of these around: helium for leak detection, dry nitrogen or argon for protecting sensitive components, etc.

H is for Half-wave plates These devices allow you to rotate the polarization of a light beam by an arbitrary angle. A half-wave plate and a polarizing beamsplitter make a great variable attenuator/ adjustable beamsplitter.

I is for Isolators These use magnetic fields and special crystals to allow light to pass only in one direction. They’re essential protection for diode laser systems, which can be thrown off by getting light scattered back into the laser.

J is for Junk drawer Every lab has one, and it will turn out to contain the damnedest things. This is where you find the weird plumbing fittings and electrical adapters that will turn out to be essential to the operation of some piece of apparatus.

K is for Kinematic mirror mounts These allow you to bounce laser beams around to where you need them, and make very fine adjustments to the position. You’ll need more of these than you think– make a guess at how many you’ll need, and then triple your order.

L is for Lenses These are used to change the size of laser beams. They come in all shapes and sizes, except the exact one you need right now.

M is for Mirrors These go in the kinematic mounts from K. Order at least as many mirrors as mounts.

N is for Notebooks It’s not science if it’s not repeatable, and you’ll need a record of everything you do and how you did it.

O is for Oscilloscopes Lots of them. Pretty much any effect you’re trying to measure will involve a time-varying voltage at some point, and oscilloscopes are what you use to make sure the voltages are varying in the right way.

P is for Posts All those mirror mounts and other elements need to be mounted on something, and these are them. As with mirrors and mounts, you’ll need more than you think– make a guess at how many you need, and multiply by five.

Q is for Quarter-wave plates These change linear polarization to circular polarization, and are essential for polarization control. Two of them in sequence make a half-wave plate, which can be useful as well.

R is for Radio frequency electronics Every experiment will use RF electronics at some point– acousto-optic modulators are driven at hundreds of megahertz, a plasma discharge requires at least tens of megahertz, lots of signals happen at RF rates.

S is for Screws You need these to fix all the mirrors, lenses, and other optics in place in their various mounts. You will need these in unimaginable numbers. Fortunately, they’re cheap.

T is for Temperature controllers Diode lasers are extremely sensitive to temperature, and thus must be controlled to within a small fraction of a degree to keep the proper frequency.

U is for Unistrut hardware These are basically really big Tinkertoys for heavy-duty construction. Every lab has some of this, usually in the form of a shelf holding up something heavy, fragile, and extremely expensive.

V is for Vacuum pumps You need something to actively maintain a low pressure environment to make sure that your experiment only sees the atoms you want, and not random crap from the air.

W is for Windows The atoms are inside the vacuum system, the lasers are outside. You need vacuum windows to get the light to the atoms. Ideally, these should be anti-reflection coated at the appropriate wavelengths.

X is for X-Y-Z translation stage As the name suggests, this is a device that gives you precise control over the position of some element in three dimensions.

Y is for Young students They’re the ones who do the real work, and get most of the benefit of working in the lab.

Z is for Zeeman slower magnet This is awfully specific, but it was hard to come up with anything else beginning with Z. A Zeeman slower uses a spatially varying magnetic field to help slow a beam of atoms from room-temperature thermal velocities in the neighborhood of the speed of sound down to a few meters per second or less, where they can be laser cooled and trapped efficiently.

That’s my list of the ABC’s of experimental AMO physics. There are numerous letters for which it was difficult to cut things down to just one choice, and I’m sure some people would argue with my choices. That’s what blog comments are for…


  1. #1 Jacob
    September 3, 2010

    I should teach my two year old all of this stuff to say along with his ABC’s. I think we have all but two of those in the physical chemistry lab I work in (we don’t have fiber optics or a Zeeman slower).

  2. #2 Frank
    September 3, 2010

    Great list. An option for a less specific ‘Z’: Zero order waveplate. (This means changing Q, maybe “1/4-20 screws”, which are abundant in any optics lab, or something “quartz-ish”). Course, now ‘S’ needs changing to any number of things (spectrometer?).

  3. #3 anon
    September 3, 2010

    L is also for Lathe, which is where you should look if your Posts start disappearing. (They make great turning stock, especially the stainless ones.)

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