Results 251 to 260 of about 7,316 (282)

Segmented Mirrors For Atmospheric Compensation

SPIE Proceedings, 1989
An optical wavefront propagating through the atmosphere will be perturbed by local variations in the refractive index of the atmospheric gases. When accumulated over long optical path distances they will impart a spatial and temporally random distortion to the wavefront.
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Position sensors for segmented mirror

SPIE Proceedings, 2004
There are currently several projects for giant telescopes with segmented mirrors under way. These future telescopes will have their primary mirror made of several thousand segments. The main advantage of segmentation is that it enables the active control of the whole mirror, so as to suppress the deformations of the support structure due to the wind ...
Didier Roziere, Sebastien Buous, Alain Courteville   +2 more
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Control of Thermal Deformations of Spherical Mirror Segment

Journal of Spacecraft and Rockets, 1996
Control of thermal deformations of a thin hexagonal spherical mirror segment using discrete and distributed actuators is presented. To determine the effectiveness of the actuators in controlling the thermal deformations of the mirror segment, a comparative study is conducted using two different models of the mirror‐ actuator system: 1) the mirror ...
P. Mohan, Rakesh Kapania, A. Jakubowski
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Optimal wavefront control for adaptive segmented mirrors

Applied Optics, 1989
A ground-based astronomical telescope with a segmented primary mirror will suffer image-degrading wavefront aberrations from at least two sources: (1) atmospheric turbulence and (2) segment misalignment or figure errors of the mirror itself. This paper describes the derivation of a mirror control feedback matrix that assumes the presence of both types ...
J D, Downie, J W, Goodman
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Deformable segmented mems mirror

The Journal of the Acoustical Society of America, 2005
A MEMS device having a deformable segmented mirror. The mirror includes a plurality of movable segments supported on a substrate using spring vertices, each vertex having a fixed plate and one or more springs. In a representative embodiment, three springs support each movable segment, where each spring connects the movable segment to a different spring
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Segmented mirrors for atmospheric compensation

Optical Engineering, 1990
An optical wavefront propagating through the atmosphere will be perturbed by local variations in the refractive index ofthe atmospheric gases. When accumulated over long optical path distances they will impart a spatial and temporally random distortion to the wavefront.
openaire   +1 more source

Generation of an optical vortex with a segmented deformable mirror

Applied Optics, 2008
We present a method for the creation of optical vortices by using a deformable mirror. Optical vortices of integer and fractional charge were successfully generated at a wavelength of 633 nm and observed in the far field (2000 mm). The obtained intensity patterns proved to be in agreement with the theoretical predictions on integer and fractional ...
Robert K, Tyson, Marco, Scipioni, Jaime, Viegas   +2 more
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Measurement accuracy in control of segmented-mirror telescopes

Applied Optics, 2004
Design concepts for future large optical telescopes have highly segmented primary mirrors, with the out-of-plane degrees of freedom actively controlled. We estimate the contribution to errors in controlling the primary mirror that results from sensor noise and, in particular, compare mechanical measurements of relative segment motion with optical wave ...
Douglas G, MacMartin, Gary, Chanan
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Absolute phasing of segmented mirrors

Optical Society of America Annual Meeting, 1990
Very large space-borne telescopes have primary mirrors made of several independent segments that must be aligned to a fraction of a wavelength for optimum performance. All proposed solutions for such phase alignment appear to have some limitations.
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Modern control for the secondary mirror of a Giant Segmented Mirror Telescope

SPIE Proceedings, 2003
ABSTRACT To achieve diffraction-limited seeing with the next generation of giant telescopes will require a multi-tiered approach employing both active and adaptive optics. Before removing atmospheric effects via adaptive optics, the telescope structure must be actively controlled to remove structural dynamics effects from the optical wavefront.
Mark S. Whorton, George Z. Angeli
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