Kolloquiumsvortrag: Dr. Thomas Ruppel, Direktor Optronics Systems, Carl Zeiss AG / 02.02.15

02.02.2015 von 16:45 bis 18:15

Institut für Elektrotechnik und Informationstechnik, Kaiserstr. 2, Raum: "Aquarium" Geb. D

Titel: Using optical system theory for modal control of large deformable mirrors at almost speed of light



According to optical system theory, a classical convex optical lens can produce the exact optical Fourier transform of an object placed in front of the lens as an image behind the lens. Thereby, the transformation occurs with the speed of light. This property is well known for decades and used e.g. for design of optical object tracking and object identification systems. A similar property of optical phase holograms instead of convex lenses can be used to achieve general linear coordinate transformations and allows the design of optical modal sensor systems that operate at the speed of light.

In this talk, high performance control of large deformable secondary mirrors for astronomical infrared telescopes using optical modal sensor systems is discussed. The large deformable mirrors, typically around one meter in diameter, incorporate hundreds to thousands of voice coil actuators and are actively deformed within milliseconds for optical image correction at the telescope. The main challenge for high performance control of these mirrors is the required computation time for  actuator signal generation based on surface measurements of the deformable mirror. Here, a significant reduction of computation time can be achieved by modal control and optical coordinate transformations within the sensor system.  The required sensor eigenfunctions can determined based on a linear model of the deformable mirror. The mirror model includes physical constraints and contains different rotationally symmetric boundary conditions.  During the talk, experimental results for modal control of large and small deformable mirrors are shown and the overall control structure for opto-mechanical modal control of deformable secondary mirrors for large telescopes at almost speed of light is discussed.

Prof. Meurer

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