Experiments to Control Atom Number and Phase-Space Density in ...
Experiments to Control Atom Number and Phase-Space Density in ...
Experiments to Control Atom Number and Phase-Space Density in ...
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<strong>in</strong><strong>to</strong> the CO2 laser. The optical layout for the frequency-offset lock is shown <strong>in</strong> figure<br />
7.30.<br />
Fabry-<br />
Perot<br />
To Wavemeter<br />
f=25mm<br />
f=50mm<br />
f=200mm<br />
f=25mm<br />
50:50 beam splitter<br />
cube<br />
ber coupler<br />
mirror<br />
spherical lens<br />
pho<strong>to</strong>diode<br />
from Tapered Amplier Master Laser<br />
from Imag<strong>in</strong>g Laser<br />
from Spectroscopy Laser<br />
polariz<strong>in</strong>g bBeam<br />
splitter cube<br />
Figure 7.30: Optical layout of the frequency-offset lock optics.<br />
A 50:50 fixed ratio beamsplitter (Edmund Optics, NT49-005) distributes the<br />
spectroscopy laser <strong>in</strong><strong>to</strong> two beam paths. A second 50:50 fixed ratio beamsplitter cube<br />
then comb<strong>in</strong>es the spectroscopy laser with the imag<strong>in</strong>g laser beam. An identical setup<br />
overlaps the spectroscopy laser with the master laser seed<strong>in</strong>g the tapered amplifier. After<br />
the beams are comb<strong>in</strong>ed, they are focused on<strong>to</strong> pho<strong>to</strong>diodes that detect the <strong>in</strong>terference<br />
signal between the spectroscopy <strong>and</strong> the imag<strong>in</strong>g laser, <strong>and</strong> the spectroscopy <strong>and</strong> the<br />
master laser respectively. To create the <strong>in</strong>terference signal, the polarizations of the<br />
beams have <strong>to</strong> be aligned.<br />
The rema<strong>in</strong><strong>in</strong>g beam power from all three beams, spectroscopy, imag<strong>in</strong>g <strong>and</strong><br />
master, is then comb<strong>in</strong>ed at a third 50:50 beamsplitter cube. The beam from one of<br />
the two output ports of this beam splitter is then coupled <strong>in</strong><strong>to</strong> the wavemeter us<strong>in</strong>g<br />
a multimode fiber. The second beam is coupled <strong>in</strong><strong>to</strong> a home-built Fabry-Perot cavity.<br />
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