Papers by Keyword: Deformable Mirror

Abstract: Chaotic genetic algorithm (CGA) is presented as an optimization algorithm for sensorless adaptive optics system to compensate atmospheric wave aberration. Chaos search strategy is incorporated into standard genetic algorithm by the logistic function that possess convergent, bifurcating, and chaotic characteristics during evolution to control the convergence of genetic algorithm. A real number encoding method is adopted in the search process and CGA is used to control a 61-actuator deformable membrane mirror (DM).The algorithm uses light intensity detected on the focal plane as the objective function to optimize, and the simulation results show CGAperforms faster than GA and thus can effectively be used in AO systems.

Abstract: A small deformable mirror which realizes concave shape as well as convex shape has been developed. In addition, this deformable mirror was developed to realize long term stability. For this purpose, a new push-pull actuator using two multilayered piezoelectric actuators aligned inline was designed. In this process, a practical method for simulating the property of piezoelectric actuator in the finite element method was proposed. From the experimental results, it was confirmed that newly developed deformable mirror has the ability to make complex profiles. Furthermore, efficiency of proposed simulation method was also confirmed.

Abstract: This paper demonstrates that the deformation of the piezoelectric deformable mirror (DM) is proportional to the transverse piezoelectric coefficient of the lead zirconate titanate (PZT) by the theoretical analysis. The optimal polarization conditions were obtained by experiments to optimize the performance of the DM. After the optimal polarization, the transverse piezoelectric coefficient of the PZT film increases from 350 pm/V to 431 pm/V, which will improve the deformation of the DM.

Abstract: Ultraprecise piezoelectric deformable mirrors have been developed to construct adaptive X-ray focusing optics whose optical parameters can be varied while simultaneously performing wavefront correction. We designed and developed a deformable mirror that did not have high-spatial-frequency deformation errors. Using a Fizeau interferometer, we demonstrated that the mirror could be deformed with a peak-to-valley figure accuracy of 5 nm. In addition, wave-optical simulations based on the Fresnel–Kirchhoff integral revealed that the mirror could focus hard X-rays to 90 nm under diffraction-limited conditions.

Abstract: Magnetic fluid based liquid mirrors represent a promising technology. Compared with the conventional solid mirrors, magnetic fluid deformable mirrors (MFDMs) have the advantages of large strokes, low cost and easy scalability. In this paper, the brief history of the development of MFDMs was first introduced, the working principle of MFDMs with fluid mechanics and electromagnetic field was presented next and then the advantages of MFDMs as well as their challenges are discussed.

Abstract: Recently, magnetic fluid deformable mirrors (MFDMs) were proposed as a novel type of wavefront correctors for adaptice optics (AO) systems, which offer cost and performance advantages over existing wavefront correctors. These mirrors are developed by coating the free surface of a magnetic fluid with a thin reflective film of nano-particles. The reflective surface of the mirrors can be deformed using a locally applied magnetic field and thus serves as a wavefront corrector. In this paper, the working principle of MFDMs is first presented, then the perspectives of MFDMs that will have to be addressed before they can be finally used practically in AO applications are discussed.

Abstract: A new hexagonal actuator arrangement continuous face-sheet MEMS deformable mirror is proposed, a mirror array with 19 elements is fabricated by a surface micromachining process. This design has a good fitting capability and a fast dynamic response. The fabricated sample is tested by an optical profiler. Simulation and test results indicate that it has a small aperture size, a high fill factor, a fast response time and a high working bandwidth. This new device provides a possibility of manufacturing a large-actuator-count DM for high speed wavefront control.

Abstract: Ultrasonic techniques have been proposed to determine the extension of piezoelectric multilayer actuators which can be used to construct deformable mirrors for adaptive optics. In the time domain approach, pulse-echo measurements were carried out using an ultrasonic transducer integrated with the actuator. In the frequency domain approach, the frequency shift of the integrated transducer was used to estimate the extension by analysis of the resonant spectrum for impedance magnitude. Time and frequency domain measurements were carried out on large actuators (7×7×28 mm3). Frequency domain measurements were carried out on smaller actuators (2×2×2 mm3) which are more suitable for a miniaturised deformable mirror. Monolithic integration of the ultrasonic extension sensing transducer and the actuator was demonstrated using layers in the multilayer actuators. Strong correlation was observed between the travel time of the ultrasonic pulse through the actuator and the simultaneously-measured actuator extension. It was noted, contrary to common prediction, that the travel time of the signal was earlier when the actuator was extended. Results are presented on the development of the device design, the characteristics of the prototype device and the accuracy of the sensing techniques.