Alignment Steps

General Procedure

We align the Plug Beam (760nm) to the magnetic zero of the quadrupole (QP) trap. Then we align one of our dipole trapping beams (1054nm) "Dipole 1" to optimally load atoms from the plugged QP trap. Next we align the second dipole beam "Dipole 2" to cross Dipole 1 at about the position of the magnetic zero, providing a tight confinement when the QP coils are shut off. In this way we load atoms into a tight crossed dipole trap (XDT). The optical lattice beams are each aligned to the position of the XDT.

Plug Beam Alignment

For rough plug alignment, tune the Ti:Saph to resonance, and coarsely align using the killing of atoms. Then take a fluorescence image of the plug beam, and overlap the fluorescence with the in-trap position of the QP trapped cloud.

For fine alignment, once you can see an effect of the plug beam, walk the mirror knobs in the direction of decreasing OD (see Lattice Lab Book 10, Dec 10th). Should eventually see a big increase in OD when you plug the magnetic zero. Then try to evaporate to a low RF value like 0.3MHz and minimize the width of the cloud in a long (~15ms TOF) image. Should be able to get a BEC in the QP trap with good plug alignment.

For optimal loading of the dipole trap, it is best to have the plug beam vertically a little bit above the magnetic centre (closer to the imaging window). Look at an in-trap image of the cloud, and move the plug around until the atoms look 'heart-shaped'.

Heart

Dipole Trap Alignment

Optical Lattice Alignment

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