Open Access
Table 1
Simulation parameters.
| 8 m-class telescope | 39 m-class telescope (ELT) | |
|---|---|---|
| Telescope | ||
| Pupil diam. (m) | 8 | 39 |
| Pupil samp. (pix) | 220 | 512 |
| Obs. ratio (%) | 11.1 | 28.3 |
| Zenith angle (deg) | 30 | 30 |
| Turbulence | ||
| Profile | 4 layers (see Agapito et al. 2014, Table 10) | 35 layers “median” profile (see Sarazin et al. 2013) |
| Outer scale (m) | 40 | 25 |
| WFS | ||
| No. sub-apertures | 40 × 40 (max) | 90 × 90 |
| Sub-pupils separation (pix) | 48 | 108 |
| Field-of-view (ф) (arcsec) | 2.1 | 2.1 |
| Sensing wavelength (nm) | 750 | 798 |
| 0-mag. det. flux (Gphm−2 s−1) | 6.37 | 1.87 |
| Photon noise | Yes | Yes |
| Excess noise | Yes | Yes |
| Read-out noise (e-) | 0.3 | 0.3 |
| DM | ||
| Conjugation altitude (m) | 0 | 0 |
| No. actuators | 672 | – |
| No. modes | 630 | 4098 |
| Modal basis | Tip and tilt plus 628 KL modes | Tip and tilt plus 4096 KL modes |
| Control | ||
| Approach | Modal | Modal |
| Reconstruction matrix | Least square solution | Minimum mean square error estimator |
| Temporal control | Leaky integrators | Leaky integrators |
| Framerate (Hz) | 1700−250 | 1000 |
| Delay (ms) | 2–5 | 3 |
Notes. Further details can be found in Appendix A. ELT is Extremely Large Telescope (Tamai et al. 2020), DM is deformable mirror, and KL is Karhunen-Loéve (Wang & Markey 1978).
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