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Update SOPHIE Alignment

watts
2024-05-02 15:19:09 +02:00
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SOPHIE-Alignment.md

@@ -40,8 +40,30 @@ In this design the virtual drift is determined by the long reference mirrors in
| ![Ref_Mirror_combi_view](uploads/d38a778a85914474d4493113f1d3fd23/Ref_Mirror_combi_view.jpg) |
|:--:|
| Figure 3. Design drawings and 3D render of the reference mirrors. The [alignment screws](https://www.thorlabs.com/thorproduct.cfm?partnumber=P25SB100V) ([P25SB100V](uploads/48b6c202c417e8f890c64728ddda7d4a/P25SB100V-AutoCADPDF.pdf)) have a thread of 1/4''-100 and so each full turn will change the local mirror height by XX. |
| Figure 3. Design drawings and 3D render of the reference mirrors. The [alignment screws](https://www.thorlabs.com/thorproduct.cfm?partnumber=P25SB100V) ([P25SB100V](uploads/48b6c202c417e8f890c64728ddda7d4a/P25SB100V-AutoCADPDF.pdf)) have a thread of 1/4''-100 and so each full turn will change the local mirror height by 25.4 microns (clockwise to raise mirror face). Turning the 2 upper screws by a full turn in opposite directions will adjust the tilt of the mirror by 0.282 mrad. |
## Fixing the SOPHIE Alignment
### Characterise the Virtual Drift
1. Ensure that no software drift correction is being applied by checking the values of zCorrectMatrix in the [Orocos Deployer](https://gitlab.psi.ch/microspectro/pixelator/-/wikis/Running-Orocos) and then setting both elements to zero:
```
Sensor1.zCorrectMatrix[0] = 0.0
Sensor1.zCorrectMatrix[1] = 0.0
```
2. Open the interferometer EPICS panel to see the raw outputs from the J/K interferometers before they are translated into X/Y positions. These values will be in terms of fringes and can be interpreted in microns by multiplying by the sensor resolution factor set in [`start.ops`](https://gitlab.psi.ch/microspectro/pixelator/-/blob/master/PixelatorRealtime/startup/SIM/start.ops?ref_type=heads#L45) (0.0001545388). (Alternatively, turn off the transformation by setting `Sensor1.transform=0` in [`start.ops`](https://gitlab.psi.ch/microspectro/pixelator/-/blob/master/PixelatorRealtime/startup/SIM/start.ops?ref_type=heads#L49), which will also disable the software drift correction).
3. Switch off the sample stage feedback by jogging the coarse sample stage.
4. Note the interferometer values and ZP-Z position.
5. Move the ZP-Z stage by a defined amount.
6. Note the new interferometer values and ZP-Z position.
7. Calculate the effective mirror tilts of the J and K interferometer reference mirrors.
8. Calculate the number of screw turns required to remove the calculated tilt from the reference mirrors.
### Fix the Virtual Drift
Apply the calculated screw turns to make the reference mirror parallel and then further adjust the interferometer components to compensate the beam alignment and optimise the signal strength.
### Characterise and Fix the Real Drift (Requires X-rays)