Second Week

Nothing much changed throughout the second week, did more of the same. On Tuesday, I called Isomet and Crystal Technology to obtain more information and price quotes for several models of AOMs for John Lorenz.

Most of my Wednesday was spent in laser safety training to become an unrestricted user for class 3B and 4 lasers (Laser Safety). Most of the lasers I'd be using in the lab are up to a few hundred milliwatts of power, but it was probably a good idea to obtain the training anyways. Most of the information was commonsense, but there was some interesting information, such as being able to injure the eye through expanding gases.

The rest of my week was spent on learning more about saturated absorption. John spend a fair amount of time explaining what we would be expecting to see in the saturated absorption, such as the orientation of the peaks for both hyperfine transitions and crossover resonances. In short, the laser frequency the atoms see are due to Doppler shifts caused by the atoms moving either towards or away from the laser, leading to Doppler broadening. If I remember correctly, if the Doppler broadened transitions are wider than the hyperfine transitions, we should expect to see crossover resonances because the atoms in the velocity of the atoms causes them to see different light frequencies and to become excited to a state not necessarily tuned to by the frequency of the laser. This causes the atoms to be absorb (reduced transmitted laser intensity) light of certain frequencies and not others depending on the state population of the atoms. Pumping atoms out of one state causes an increased transmission of light corresponding to that transition. If the width of the Doppler broadened transition is smaller than the frequency between hyperfine transitions, no crossover resonances should occur. This is because the atoms are not moving fast enough to produce enough of a Doppler shift to become excited into a different state than the one the laser is tuned to.

On Friday, I began setting up a layout for a saturated absorption laser spectroscopy. It should be a relatively simple setup on the optics table, but the space restrictions made it difficult to separate the probe beam from the pump beam. After a bit of fiddling, the setup is mostly complete with only a few adjustments to be made on Monday.