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David Notebook: Difference between revisions
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==Daily Log==
'''7/28/14'''
Further measurements on Friday showed that the beam actually still diverged quite a bit after the telescope, to the point where it won't be useful. The performance seems limited by the laser/a-sphere which will not fully collimate out of the fiber. I'm switching out the 110 a-sphere on the output for a 230. It doesn't collimate quite as well, but with a shorter focal length, I'm hoping it will be smaller over a propagation distance of about 1 meter.
{| class="wikitable sortable"
|-
! Path Length from Lens (cm) !! Horizontal Size (μm) !! Vertical Size (μm)
|-
| 34|| 595|| 510
|-
| 40|| 615|| 540
|-
| 65|| 970|| 820
|-
|84||1380 || 1250
|}
Looks like the first asphere was better over this distance range.
'''7/23/14'''
The camera was extremely temperamental. The XP computer in the other lab room would recognize it and work, but the laptop would not. I re-installed the software/drivers, which didn't fix it right away, but eventually I got it working. I couldn't say what I did. The upper USB port on the right side of the laptop worked for it though--some of them seem to give better luck than others. With the TA all the way up, the beam is way too strong for the camera to properly image, but I don't want to turn down the power in case it affects the beam size. I put in a 780 notch filter, which always it to be imaged without overloading at the shortest shutter speed and low sensitivity. I don't think the notch filter should affect the shape much, especially since the beam has already been filtered by the fiber and should be almost all at 780 nm. I turned the chopper off since it runs at a similar frequency to some of the shutter speed options and was interfering. The beam looks very Gaussian as expected.
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