Source: http://proxy.osapublishing.org/oe/abstract.cfm?uri=oe-25-24-29916
Timestamp: 2019-04-23 06:57:59+00:00

Document:
Deformable mirror (DM) used for intracavity compensation in high-power lasers should be able to withstand very high laser intensity. This paper proposes a water-cooled unimorph DM which can withstand the laser power up to 10 kW in thermal simulation. The proposed DM consists of an annular PZT layer and a circular Si layer which are glued together with edge clamped. All the 32 piezoelectric actuators are distributed around the correction area and on the front side of the DM. The cooling water flows through the back side of the DM and cools the mirror directly. This design realizes the physical separation of the actuators and the coolant. The experimental results of a fabricated DM prototype show that the DM can reproduce typical low-order aberrations accurately with relatively large amplitude. The wavefront PV amplitudes of the reproduced tip/tilt, astigmatism, defocus, trefoil and coma shapes for 15 mm aperture are about 40 μm, 24 μm, 18.7 μm, 10 μm and 6 μm, respectively.
W. Koechner, Solid-state Laser Engineering (Springer, 2013).
T. Y. Cherezova, S. S. Chesnokov, L. N. Kaptsov, V. V. Samarkin, and A. V. Kudryashov, “Active laser resonator performance: formation of a specified intensity output,” Appl. Opt. 40(33), 6026–6033 (2001).
W. Clarkson, “Thermal effects and their mitigation in end-pumped solid-state lasers,” J. Phys. D Appl. Phys. 34(16), 2381–2395 (2001).
E. Wyss, M. Roth, T. Graf, and H. P. Weber, “Thermooptical compensation methods for high-power lasers,” IEEE J. Quantum Electron. 38(12), 1620–1628 (2002).
S. Makki and J. Leger, “Solid-state laser resonators with diffractive optic thermal aberration correction,” IEEE J. Quantum Electron. 35(7), 1075–1085 (1999).
R. R. Stephens and R. C. Lind, “Experimental study of an adaptive-laser resonator,” Opt. Lett. 3(3), 79–81 (1978).
J. M. Spinhirne, D. Anafi, R. H. Freeman, and H. R. Garcia, “Intracavity adaptive optics. 1: Astigmatism correction performance,” Appl. Opt. 20(6), 976–984 (1981).
W. Lubeigt, G. Valentine, and D. Burns, “Enhancement of laser performance using an intracavity deformable membrane mirror,” Opt. Express 16(15), 10943–10955 (2008).
S. Kokorowski, “Analysis of adaptive optical elements made from piezolectric bimorphs,” J. Opt. Soc. Am. 69(1), 181–187 (1979).
E. Steinhaus and S. Lipson, “Bimorph piezoelectric flexible mirror,” J. Opt. Soc. Am. 69(3), 478–481 (1979).
P. Hyunkyu and D. A. Horsley, “Single-crystal PMN-PT MEMS Deformable Mirrors,” J. Microelectromech. 20(6), 1473–1482 (2011).
P. Rausch, S. Verpoort, and U. Wittrock, “Unimorph deformable mirror for space telescopes: environmental testing,” Opt. Express 24(2), 1528–1542 (2016).
C. Reinlein, M. Appelfelder, S. Gebhardt, E. Beckert, R. Eberhardt, and A. Tünnermann, “Thermomechanical design, hybrid fabrication, and testing of a MOEMS deformable mirror,” J. Micro/Nanolith. MEMS MOEMS 12(1), 013016 (2013).
M. Gerber, T. Graf, and A. Kudryashov, “Generation of custom modes in a Nd: YAG laser with a semipassive bimorph adaptive mirror,” Appl. Phys. B 83, 43–50 (2006).
V. Samarkin, A. Aleksandrov, V. Dubikovsky, and A. Kudryashov, “Water-cooled bimorph correctors,” Proc. SPIE 6018, 60180Z (2005).
J.-H. Lee, Y.-C. Lee, and E.-C. Kang, “A cooled deformable bimorph mirror for a high power laser,” J. Opt. Soc. Korea 10(2), 57–62 (2006).
A. V. Kudryashov and V. V. Samarkin, “Control of high power CO2 laser beam by adaptive optical elements,” Opt. Commun. 118, 317–322 (1995).
L. N. Kaptsov, A. V. Kudryashov, V. V. Samarkin, and A. Seliverstov, “Control of parameters of solid-state industrial YAG: Nd3+ laser radiation using methods of adaptive optics. II. Spherical adaptive mirror,” Sov. J. Quantum Electron. 22(6), 533–534 (1992).
C. Zhou, Y. Li, A. Wang, and T. Xing, “Concept and Modeling Analysis of a High Fidelity Multimode Deformable Mirror,” Appl. Opt. 54(17), 5436–5443 (2015).
R. Bastaits, D. Alaluf, M. Horodinca, I. Romanescu, I. Burda, G. Martic, G. Rodrigues, and A. Preumont, “Segmented bimorph mirrors for adaptive optics: segment design and experiment,” Appl. Opt. 53(29), 6635–6642 (2014).
G. T. Kennedy and C. Paterson, “Correcting the ocular aberrations of a healthy adult population using microelectromechanical (MEMS) deformable mirrors,” Opt. Commun. 271, 278–284 (2007).
J. Ma, Y. Liu, T. He, B. Li, and J. Chu, “Double Drive Modes Unimorph Deformable Mirror for Low-Cost Adaptive Optics,” Appl. Opt. 50(29), 5647–5654 (2011).
L. B. Freund and S. Suresh, Thin film materials: stress, defect formation and surface evolution (Cambridge University, 2004).
J. Ma, K. Chen, J. Chen, B. Li, and J. Chu, “Closed-loop correction and ocular wavefronts compensation of a 62-element silicon unimorph deformable mirror,” Chin. Opt. Lett. 13(4), 042201 (2015).
Fig. 1 Cross-sectional view of the water-cooled unimorph DM.
Fig. 2 Finite element model of the unimorph DM: (a) mesh of the model and (b) mirror deformation under activation of Act1.
Fig. 3 Simulated wavefront profiles of the DM driven by Act1 and Act2.
Fig. 4 Simulated reconstruction of astigmatism Z3 and coma Z7.
Fig. 5 Simulation reproduction of the first 14 term Zernike modes: (a) RMS wavefront and (b) normalized residual wavefront error.
Fig. 6 Thermal effect of the DM under laser radiation with and without cooling: (a) Thermal response curve and (b) temperature profiles of DM along the radial direction at 10 seconds.
Fig. 7 Thermal wavefront deformation at 10 seconds.
Fig. 8 Photographs of the fabricated water-cooled DM: (a) unimorph DM and (b) packaged DM with cooling cavity.
Fig. 9 Comparison of simulated and measured wavefront deformation of actuator at the aperture of 20 mm.
Fig. 10 Wavefront surface of the DM at 15 mm aperture before and after filling the cooling cavity with water.
Fig. 11 Experimental reproduction of the first 14 Zernike mode shapes using closed-loop control method. The wavefront PV value and RMS value are indicated for each mode.
Fig. 12 Experimental reproduction of the first 14 term Zernike mode shapes at different apertures: (a) wavefront RMS and (b) normalized residual wavefront error.

References: V. 
 V. 

V. 
 V. 
 V. 
 V. 
 V. 
 V.