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Entry  Thu Jul 23 16:31:28 2009, Michelle, Laser, , I've done some things in lab. 
    Reply  Fri Jul 24 19:00:37 2009, rana, Laser, , I've done some things in lab. 
Message ID: 197     Entry time: Thu Jul 23 16:31:28 2009     Reply to this: 200
Author: Michelle 
Type: Laser 
Subject: I've done some things in lab. 


Today I aligned the laser beam through the EOM with something resembling a normal shape at the output. This was tricky. The powermeter isn't giving me very reasonable readouts, the aperture on the EOM is impossible to see with the IR viewer, the EOM is in the middle of the table where I can't really reach it, and it's very close to a focusing lens. The point being that I may have to tweak it a bit, but I really don't want to have to redo the alignment of that particular optic. So no earthquakes for a while.

A note on the power meter: It's been registering anywhere between -6 mW and 11 mW with no beam on it at all. I've been zeroing it before putting it in the beam before each use, but I don't know how much I trust it.

The beam shape coming out of the EOM  is still a bit funny - with one bright beam, and then a very faint ring, so it looks like a ring you would wear on your finger with a diamond on top. I am attributing this to the fact that the beam is slightly larger than the EOM's aperture; I have set it up so the center of the EOM coincides with the beam's waist. I'm also (according to the power meter) getting a high attenuation inside the EOM, but whether this is correct or normal I haven't yet figured out.

We need another mount for a beam splitter, this will go at the input to the cavity. We are also still in need of a quarter waveplate, and Aidan says he has a spare that he won't need to use for a few weeks. Also, CVI doesn't specify the damage threshold for the cavity mirrors for cw lasers, only for pulsed sources. Alastair has sent them an email requesting this information, and once we know that we can send the beam into the cavity at appropriate power levels.

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