Open Access
Table 1
Simulation parameters.
| Turbulence | |
| Profile | ESO 35 layer median |
| Outer scale | L0 = 25 m |
| Seeing* | s = 0.5, 0.8, 1.2 arcsec |
| Coherence time* | τ0 = 1, 3, 5, 7 ms |
| Telescope | |
| Diameter | D = 8 m |
| Entrance pupil | VLT pupil with spiders |
| First stage | |
| SH WFS | |
| Wavelength | λWFS = 700 nm |
| Subapertures | 40 × 40 |
| Readout noise | 0.1 electrons/pixel |
| Deformable mirror | |
| Geometry | 41 × 41 + tip-tilt mirror |
| Modal basis | 800 KL modes |
| Control loop | |
| Reconstruction matrix | Least squares method |
| Command law | Integrator + scalar gain |
| Total delay | 2.15 ms |
| Loop gain* | g1 = 0, 0.01, 0.05, 0.1, 0.2, 0.3, 0.5 |
| Second stage | |
| Pyramid WFS | |
| Wavelength | λWFS = 1.2 μm |
| Subapertures | 50 × 50 |
| Readout noise | 0.8 electrons/pixel |
| Modulation radius* | 0, 1, 3, 5, 10 λWFS/D |
| Deformable mirror | |
| Geometry | 26 × 26 |
| Modal basis | 400 KL modes |
| Control loop | |
| Reconstruction matrix | Least squares method |
| Command law | Modal integrator |
| Optical gain compensation* | CLOSE algorithm, none |
| Total delay | 2 sampling frames |
| Image formation | |
| Type of coronagraph | perfect |
| Wavelength | λ = 1.67 μm |
| Exposure time | 3 s |
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