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Table 1.
Summary of the key parameters of the NAOMI AO system.
| 2.1 Deformable mirror (ALPAO DM241) | |
|---|---|
| Tip-tilt stroke | > 40 μm (PtV WF) |
| 3 × 3 actuators stroke | 25 μm (PtV WF) |
| Pupil size | 28 mm |
| Actuator counts | 241 total, ∼145 effective |
| Actuator per sub-aperture | ∼4 |
| Number of controlled modes | 14 Zernikes (after piston) |
| Settling time | < 1.6 ms |
| 2.2 Wavefront sensor (ANDOR iXon Ultra 897) | |
| Type | Shack-Hartmann |
| Sub-apertures | Square – 4 × 4 array |
| Nb of valid sub-apertures | 12 |
| Pixel scale | 0.375″ pix−1 |
| Sub-aperture acquisition | 16 × 16 or 6″ × 6″ |
| Sub-aperture closed loop | 6 × 6 or 2.25″ × 2.25″ |
| Lenslet array pupil diameter | 2.05 mm |
| Lenslet array focal length | 20 mm |
| Readout noise | 0.32 e− (sensitive mode) |
| Clock-induced charges | 0.002 e− pix−1 |
| Pixel size | 32 mm (2 × 2 binned) |
| Shortest integration time | 1.731 ms |
| Pixel count | 64 × 64 |
| Wavelength | 450 nm–900 nm |
| 2.3 Real-time controller (SPARTA Light) | |
| Loop frequency | 500 Hz to 50 Hz |
| Controller latency | < 1 ms |
| Full loop delay | 4.6 ms |
| Reconstructor update | < 0.2 Hz |
| Slope measurement | Weighted Centre of Gravity |
| Wavefront reconstruction | Modal MVM |
| Additional capabilities | Chopping, vibration control |
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