Adaptive optics — Shape control of an adaptive mirror

1990 ◽  
pp. 28-45 ◽  
Author(s):  
C. Truchi
Keyword(s):  
Adaptive Optics ◽  
Shape Control ◽  
Adaptive Mirror

scholarly journals Thermal Balance and Active Damping of a Piezoelectric Deformable Mirror for Adaptive Optics

Actuators ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 75 ◽  
Author(s):  
Kainan Wang ◽  
David Alaluf ◽  
André Preumont
Keyword(s):  
Adaptive Optics ◽  
Mass Production ◽  
Shape Control ◽  
Active Damping ◽  
Deformable Mirror ◽  
Vibration Modes ◽  
Back Side ◽  
Structural Damping ◽  
Front Side ◽  
Piezoelectric Unimorph

Piezoelectric unimorph deformable mirrors offer a cheap solution to adaptive optics, with mass production capability. However, standard solutions have significant drawbacks: (i) the static shape is sensitive to the temperature, and (ii) the low structural damping limits the control bandwidth, because of the interaction between the shape control and the vibration modes of the mirror. This paper discusses how these two problems may be alleviated by using a mirror covered with an array of actuators working in d31 mode on the back side and a ring of transducers (actuators and sensors) on the front side, outside the pupil of the mirror.

Shape Control of an Adaptive Mirror at Different Angles of Inclination

1996 ◽  
Vol 7 (2) ◽  
pp. 203-210 ◽  
Author(s):  
Rolf Paradies ◽  
Manfred Hertwig ◽  
Wilfried J. Elspass
Keyword(s):  
Shape Control ◽  
Adaptive Mirror

Active Stiffeners for Vibration Control of a Circular Plate Structure: Analytical and Experimental Investigations

2005 ◽  
Vol 127 (5) ◽  
pp. 441-450 ◽  
Author(s):  
Michael K. Philen ◽  
K. W. Wang
Keyword(s):  
Vibration Control ◽  
Circular Plate ◽  
Adaptive Optics ◽  
Shape Control ◽  
Extended Period ◽  
Surface Shape ◽  
Experimental Investigations ◽  
Weight Restrictions ◽  
Plate Shape ◽  
Stringent Performance

Space-based adaptive optic systems have gained considerable attention within the past couple of decades. Achieving the increasingly stringent performance requirements for these systems is greatly hindered by strict weight restrictions, size limitations, and subjected hostile environments. There has been considerable attention in developing lightweight adaptive optics where piezoelectric sheet actuators are attached on the back of optical mirrors to achieve a high precision surface shape with minimum additional weight. Vibration control of such large flexible space structures is continually challenging to engineers due to the large number of actuators and sensors and the large number of vibration modes within the operational bandwidth. For these structures, any disturbed modes are likely to remain vibrating for an extended period of time due to the small amount of damping available. As a result, controller spillover should be minimized as much as possible to avoid exciting the residual modes. In recent investigations of circular plate shape control by [Philen and Wang, Int. Soc. Opt. Eng. 4327, pp. 709–719]. It was demonstrated that directional decoupling of the two-dimensional actuator (meaning that the actuation in one of the two directions is eliminated) improves the system performance when correcting for the lower order Zernike static deformations. This directional decoupling effect can be achieved through an active stiffener (AS) design. In this research, analytical and experimental efforts are carried out to examine the effect of the active stiffener actuators in reducing the controller spillover through the stiffeners’ decoupling characteristics. It is shown that significant reductions in controller spillover can be achieved in systems using the active stiffener actuators when compared to systems having direct attached (DA) actuators, thus resulting in improved vibration control performance. The experimental results verify the analytical predictions and clearly demonstrate the merit of the active stiffener concept.

scholarly journals Compensation of heat load deformations using adaptive optics for the ALS upgrade: a wave optics study

2020 ◽  
Vol 27 (5) ◽  
pp. 1141-1152
Author(s):  
Manuel Sanchez del Rio ◽  
Antoine Wojdyla ◽  
Kenneth A. Goldberg ◽  
Grant D. Cutler ◽  
Daniele Cocco ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Heat Load ◽  
Design Principle ◽  
Simulation Method ◽  
Wave Optics ◽  
Element Analysis ◽  
X Ray ◽  
Spatial Frequencies ◽  
Adaptive Mirror ◽  
Line Space

A realistic wave optics simulation method has been developed to study how wavefront distortions originating from heat load deformations can be corrected using adaptive X-ray optics. Several planned soft X-ray and tender X-ray insertion-device beamlines in the Advanced Light Source upgrade rely on a common design principle. A flat, first mirror intercepts the white beam; vertical focusing is provided by a variable-line-space monochromator; and horizontal focusing comes from a single, pre-figured, adaptive mirror. A variety of scenarios to cope with thermal distortion in the first mirror are studied by finite-element analysis. The degradation of the intensity distribution at the focal plane is analyzed and the adaptive optics that correct it is modeled. The range of correctable wavefront errors across the operating range of the beamlines is reported in terms of mirror curvature and spatial frequencies. The software developed is a one-dimensional wavefront propagation package made available in the OASYS suite, an adaptable, customizable and efficient beamline modeling platform.

Control System Design for Retinal Imaging Adaptive Optics Systems

2005 ◽  
Author(s):  
Maurizio Ficocelli ◽  
Foued Ben Amara
Keyword(s):  
Control System ◽  
Control Problem ◽  
System Design ◽  
Adaptive Optics ◽  
Shape Control ◽  
Retinal Imaging ◽  
Control System Design ◽  
Time Varying ◽  
Stabilizing Controllers ◽  
Deformable Membrane Mirror

This paper presents a solution to control system design issues for adaptive optics systems used in retinal imaging. In this paper, the control problem for adaptive optics systems is generalized to that of shape control for a flexible membrane representing a deformable membrane mirror. Due to the dynamic nature of the aberrations in the eye, the shape control problem addressed is the tracking of an unknown and time-varying shape for a distributed membrane (i.e., desired shape of the mirror). The design of a controller to achieve the shape control objective is based on a model of a distributed parameter system representing the mirror membrane. To accomplish this task, a multivariable centralized controller is utilized. Since the desired shape of the mirror is unknown and time-varying, the controller is tuned online to converge to the controller needed to achieve regulation. This is done iteratively, by taking advantage of the Q-parameterization of all stabilizing controllers, so that the controller will converge to the ideal controller. The online tuning is used to compensate for the lack of information of the desired shape for the deformable mirror.

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