Fig. 1. Design of the semi-passive bimorph mirror.

Fig. 2. Electrode pattern of the bimorph mirror $260~\text{mm}\times 260~\text{mm}$.

Fig. 3. Photo of the bimorph deformable mirror $260~\text{mm}\times 260~\text{mm}$ attached in its mounting.

Fig. 4. Focal spot of the output laser beam: (a) before correction and (b) after correction of the wavefront; 11 and 1.3 diffraction limited sizes correspondingly.

Fig. 5. Layout and configuration of the electrodes.

Fig. 6. Photo of the piezoelectric actuator.

Fig. 7. Combined deformable mirror: 1 – substrate with a reflective coating, 2 – actuators, 3 – metallic base.

Fig. 8. Optical scheme for the analysis of the surface of the deformable mirror: 1 – 4-inch interferometer; 2–4 – folding mirrors; 5 – $6\times$ beam expander; 6, 7 – reference surfaces; 8 – deformable mirror; 9 – beam splitter; 10 – scaling telescope; 11 – Shack–Hartmann wavefront sensor; 12 - computer with software; 13 – electronic control unit for deformable mirror.

Fig. 9. Flatness of the surface of the deformable mirror measured by wavefront sensor: (a) corrected only using the piezoelectric stack actuators ($1.517~{\rm\mu}\text{m}$ (P-V) and $0.377~{\rm\mu}\text{m}$ (RMS)); (b) corrected using also the bimorph electrodes ($0.162~{\rm\mu}\text{m}$ (P-V) and $0.033~{\rm\mu}\text{m}$ (RMS)); (c) map of control voltage applied both to stacked actuators and bimorph electrodes to flatten of the surface.

Fig. 10. Flatness of the surface of the deformable mirror, corrected using also the bimorph electrodes ($0.280{\it\lambda}$ (P-V) and $0.058{\it\lambda}$ (RMS) @ ${\it\lambda}=0.632~{\rm\mu}\text{m}$) measured with a ZYGO interferometer.

Fig. 11. Point spread function of the corrected deformable mirror surface calculated by the ZYGO interferometer software – the estimated Strehl ratio is equal to 0.859.

Fig. 12. Wavefront distortions of the output beam: (a) before correction and (b) after correction by means of wide aperture bimorph deformable mirror; (c) voltage map on the bimorph and stacked actuators of the mirror to correct of the wavefront distortions.