Tag Archives: AOM

1st Day of Christmas: Acousto-Optic Modulator

This Advent during the 24 days leading up to Christmas I thought it would be fun to have a quick introduction of scientific apparatus, in particular tools used in atomic physics research. This is a way to say thanks to their hard work for our research, and a look at how many things are really needed to make a laboratory work!

For the next 24 days I’ll feature a different apparatus each day, show its basic principles and how it is used in the lab (based on my experience, so not exhaustive). But let’s get started, semi-randomly….

Acousto-Optic Modulator

Atomic physics labs in general use a lot of lasers to manipulate atoms. Acousto-optic modulators (or usually just AOMs) are very practical tools to switch the laser beams, among other uses.

Imagine a see-through crystal that was being banged on very fast. That banging will create sounds waves in the crystal that that will travel along and create a sort of periodic structure.  Send then some light (ie. a laser beam) through the crystal perpendicular to the sound wave’s direction, and the light will see a periodic structure. The structure depends on the sound waves, and will scatter the light. Due to interference the result is multiple outgoing beams at well defined angles. We can then take advantage of splitting the outgoing beams in the experiment, by manipulating how much light is in each of the beams, and  at which angles they appear at (which angles they are diffracted to), and so on…

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