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R&D (Cryogenic)
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SatoshiTanioka - 19:36, Friday 05 July 2019 (1440)Get code to link to this report
Dip of reflected beam

Yesterday, I measured the beam profile, and the beam had its waist around 1250mm distance from FI with ~60um beam radius.
Then I adjusted the beam height to achieve ''straight'' beam.

Next, I scaned the laser freq. using both temp. control and PZT of the laser.
During scanning the freq., I monitored both transmitted beam, and reflected beam.

I could see some dips in reflection, though I could not see any transmitted beam.
I have not checked the error signal yet, it may be possible to lock the laser, but it seemes difficult to see transmitted beam.

Images attached to this report
1440_20190705121349_dipt.jpg 1440_20190705121353_dipp.jpg
Comments related to this report
SatoshiTanioka - 15:00, Monday 08 July 2019 (1444)

By rough estimation, the reflected power dropped ~0.3mW, though I could not see any transmitted flash.

The reflected beam power was ~3mW with 3.5V.
The dip was ~0.4V.
3mW * 0.4V / 3.5V ~ 0.3mW

The loss and high reflectivity may cause too small transmitted power.