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The pulse duration in the tunnel is measured after the DSHM with an SSA. The beam exits the compressor through the window in the guillotine valve, goes through the PB and the bypass line and exits through the window on the 8in cube. It is then de-magnified by a factor of 5 with a permanently installed telescope. The beam is clipped by the bypass line down to 34.8mm, the telescope then reduces it to 7mm. The SSA accepts beams from 2-8mm in diameter. The SSA is calibrated before every measurement.
Measurement 9/24/2024
http://physics-elog.slac.stanford.edu/facetelog/show.jsp?dir=/2024/39/24.09&pos=2024-09-24T23:06:00
Was able to get a clear signal to optimize the compressor spacing, difference still visible down to 50um steps.
SSA calibration:
7.95mm to 7.75mm or 200um stage travel, 400um delay. 3.41ms delay.
New calibration: 400um on stage corresponds to 3.41ms. 400um path difference is 1333fs so calibration
is 1333 fs / 3.41ms= 390.9 fs/ms.
At grating separation of 27.45
Pulse length on scope = 164 us FWHM
Pulse length (real) = 0.164 ms X 390.9 fs/ms / 1.5 = 42.7 fs FWHM
Measured three times:
| 42.7fs | 39.6fs | 43.8fs |
|---|---|---|
0.164 ms X 390.9 fs/ms / 1.5 = 42.7 fs FWHM | 0.152 ms X 390.9 fs/ms / 1.5 = 39.6 fs FWHM | 0.168 ms X 390.9 fs/ms / 1.5 = 43.8 fs FWHM |
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Measurement 1/16/2024
http://physics-elog.slac.stanford.edu/facetelog/show.jsp?dir=/2024/03/16.01&pos=2024-01-16T23:13:34
SSA calibration:
5.770mm to 5.615mm or 155um stage travel, 310um delay. 2.63ms delay.
New calibration: 310um on stage corresponds to 2.63ms. 310um path difference is 1033fs so calibration
is 1033 fs / 2.63ms= 392.9 fs/ms.
At grating seperation at 26.2
Pulse length on scope = 172 us FWHM
Pulse length (real) = 0.172 ms X 392.9 fs/ms / 1.5 = 45.1 fs FWHM
Measurement 11/8/2023
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