Biaolong set up cameras looking at the laser spot in different positions, to check for drifts or jumps. The setup is described in the elog entries
https://elog-gfa.psi.ch/Furka/780
https://elog-gfa.psi.ch/Furka/789
Here is a summary of the notes from Biaolong:
some upgrades were achieved to make the laser setup more user-freindly.
- Pico-motor change.
New panel of pico-motor at Furka: See Pic 1. The new panel called "PICO + POSIC"
a. Laser Hutch X1 & Y1
I add another pico-motor at Athos laser hutch right before the laser transferline. Because of the air pressure change between day and night, there is some drift of the laser. Using the camera SLAAT31-LCAM-C801, this drift can be compensated using this Pico-motor.
b. Experiment X1 & Y1
This is the one on the extension table for the pump laser spatial tuning.
c. Diagnostic X2 & Y2 https://elog-gfa.psi.ch/Furka/780 This is the one for the DC to control the white light pointing
Before moving the first pico-motor, Furka team better discuss with Biaolong.
The second and third pico-motors have encoder and you can see the relative position and zero the position for spatial overlap.
I have 3 cameras looking at different positions.
Pic. 1 Camera SLAAT31-LCAM-C801: exit of transfer line. FIt-X = 509.73 Fit-Y = 444.40
Pic.2 Camera SLAAT31-LCAM-C802: before the TOPAS. FIt-X = 395.53 Fit-Y = 169.97
Pic.3 Camera SLAAT31-LCAM-C804: reflection of the gate beam (or 800/400 nm pump laser). FIt-X = 429.68 Fit-Y = 639.43
Pic.4 I put them into the data buffer, you can plot them with data-ui.psi,.ch.
The PV names are:
SLAAT31-LTIM01-EVR0:DUMMY_PV1_NBS
SLAAT31-LTIM01-EVR0:DUMMY_PV2_NBS
SLAAT31-LTIM01-EVR0:DUMMY_PV3_NBS
SLAAT31-LTIM01-EVR0:DUMMY_PV4_NBS
SLAAT31-LTIM01-EVR0:DUMMY_PV5_NBS
SLAAT31-LTIM01-EVR0:DUMMY_PV6_NBS
If there is a bit drift in the PV1 and PV2 and the others have correlation with them, you can use the pico-motor in the Athos laser hutch for compensation.
An automatic beam stabilizer is planned and under investigation.
Other notes:
1 pixel is 5 microns in the laser hutch. X and Y motions of the picomotors are not independent. In the laser hutch there are no encoders, and the picomotors have backlash. A step of ~10 is ok to start tweaking.