Showing papers by "Georg Schitter published in 2010"
TL;DR: Recorded AFM images show a considerable reduction in image distortion due to the proposed control method, enabling artifact free AFM imaging at a speed of 122 lines per second with a standard piezoelectric tube scanner.
74 citations
TL;DR: This paper presents an aberration correction approach for WFSlss AO systems based on the model of the WFSless AO system and a small number of intensity measurements, where the model is identified from the input-output data of the N=9 Zernike modes by black-box identification.
Abstract: In many scientific and medical applications, such as laser systems and microscopes, wavefront-sensor-less (WFSless) adaptive optics (AO) systems are used to improve the laser beam quality or the image resolution by correcting the wavefront aberration in the optical path. The lack of direct wavefront measurement in WFSless AO systems imposes a challenge to achieve efficient aberration correction. This paper presents an aberration correction approach for WFSlss AO systems based on the model of the WFSless AO system and a small number of intensity measurements, where the model is identified from the input-output data of the WFSless AO system by black-box identification. This approach is validated in an experimental setup with 20 static aberrations having Kolmogorov spatial distributions. By correcting N = 9 Zernike modes (N is the number of aberration modes), an intensity improvement from 49% of the maximum value to 89% has been achieved in average based on N +5 = 14 intensity measurements. With the worst initial intensity, an improvement from 17% of the maximum value to 86% has been achieved based on N + 4 = 13 intensity measurements.
63 citations
TL;DR: In this article, a model-based feedback controller that controls the tip-sample interaction in dual actuated atomic force microscopy (AFM) systems is proposed to guarantee closed-loop stability, the dynamic uncertainties of the system are identified and taken into account in the controller design.
19 citations
29 Jul 2010
TL;DR: In this article, a modal actuator is modified to render modes close to the controller bandwidth uncontrollable, which can increase the robustness of modal filters due to load variation.
Abstract: In high speed AFMs the vertical axis of the sample positioning stage requires high bandwidth feedback control. In these systems the dynamics of the piezoelectric actuator, its support structure and load play a dominant role in the design of the feedback loop. System performance can be increased by avoiding the excitation of resonant modes of the piezoelectric actuator by modal actuation. In this approach, the piezoelectric actuator is modified to render modes close to the controller bandwidth uncontrollable. Due to its static hardware implementation robustness issues may emerge due to varying loads used for AFM imaging. This paper focusses on performance robustness of modal filters due to load variation.
13 citations
TL;DR: In this paper, a closed-loop adaptive optics (AO) system is used to improve the resolution of the image by actively sensing and correcting the optical aberration in the system.
1 citations
TL;DR: In this article, the authors compared the application of modal control techniques in systems based on piezoelectric tube actuators such as atomic force microscopes using finite element analysis and experimental verification.
1 citations