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The beam has a ~10-13 mm diameter (will depend on final collimation) and is uncompressed , so at around 200 ps pulse duration.
The potential fluence on the mirrors can be in excess of 1 J/cm^2.
Pre-2022 RP attenuator
Currently installed RP attenuator.
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- Appears to introduce astigmatism
- Ghosts when changing polarisation
- Loads of different optics (splitting ratio and polarisation)
Fig 1: Currently installed RP-attenuator. Red arrows indicate the beam path.
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Attenuation should be down to 0.35^4 = 0.015 (1.5%) or 800 mJ * 0.35^4 = 12 mJ
Henrik's test setup (originally placed just outside the MPA):
Fig 2: Test setup for new RP-attenuator. Was installed just outside MPA.
Reflectivity tests
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