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Showing 1 to 20 of 20 for “"wavefront sensor"”.
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Development of a new Infrared Pyramid Wavefront Sensor
… for astronomical observations is sensing the wavefront at near-infrared wavelengths, where many bright stars are found, which can be used as guide stars and have no visible counterparts. A pyramid wavefront sensor was chosen due to its advantages over the Shack-Hartmann sensor. It is expected …
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A CCD based curvature wavefront sensor for Adaptive Optics in Astronomy
… gibt es eine Reihe verschiedener Wellenfrontsensoren. Einer davon ist der 'Curvature'- Wellenfrontsensor, was soviel wie 'Krümmungs'- Wellenfrontsensor bedeutet. An der Europäischen Südsternwarte (ESO) in Garching werden für das Very Large Telescope (VLT) und das VLT Interferometer (VLTI) …
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The design, construction and evaluation of a real time optical wavefront sensor
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1988.
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A 3-sided Pyramid Wavefront Sensor Controlled by a Neural Network for Adaptive Optics to reach diffraction-limited Imaging of the Retina
… aberrations with the novel 4-sided pyramid sensor have confirmed the benefits of this sensor compared with conventional wavefront sensors. This work presents a pyramid wavefront sensor for the measurement of aberrations and their compensation on a confocal laser scanning ophthalmoscope. By …
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High Space -Bandwidth Wavefront Sensing by Sampling and Spatial Multiplexing
The SFS is a breakthrough concept in wavefront sensor design. It is, to our knowledge, the first high-accuracy, high-resolution, vibration-insensitive, one-shot wavefront sensor. It achieves high accuracy by using a phase-shift shearing interferometric approach in detecting wavefront phase …
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The Adaptive Optics Lucky Imager: combining adaptive optics and lucky imaging
… the adaptive optics system and a new type of wavefront sensor, the non-linear curvature wavefront sensor (nlCWFS), being used within the instrument. The development of the nlCWFS has been the focus of my work, bringing the technique from a theoretical concept to physical realisation at the WHT …
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Adaptive optics aberrometer and wavefront corrector using a twisted-nematic liquid-crystal on silicon chip
… optics system for the correction of ocular wavefront errors using a twistednematic liquid-crystal on silicon (TN-LCoS) chip as the wavefront corrector in conjunction with a Hartmann-Shack device as the wavefront sensor. TN-LCoS chips are originally designed to be used as mass-manufactured, …
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A CMOS-based Hartmann-Shack Sensor for Real-Time Adaptive Optical Applications
… In every adaptive system there is the need for a sensor and an actuator. The Hartmann-Shack wavefront sensor uses the displacement of spots in the focal plane of a lenslet array for subsequent calculation of the wavefront. The bandwidth of current sensors is mostly limited by software processing …
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Tomographic Reconstruction of Wavefront Aberrations using Multiple Laser Guide Stars
… class) telescopes (ELT). Modal decomposition of wavefront phase using Zernike polynomials is a widely used technique in adaptive optics (AO) research. However, this approach breaks down with the large number of degrees of freedom required by ELTs.This research proposes the use of an alternative …
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Measuring Corneal Topography Using Wavefront Analysis Technique
… a corneal topographer based on a Hartmann-Shack wavefront sensor for measuring corneal elevation over a spherical surface, is presented in this thesis. The performed tests of the topography system showed a high accuracy and reproducibility of the measurements on spherical as well as on toric test …
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Analysis of spatial mode sensitivity of gravitational wave interferometer and targeted search for gravitational radiation from the Crab pulsar
… system. We describe a frequency resolving wavefront sensor, called the phase camera, which was used on the interferometer to examine the heating effects and corrections of the thermal compensation system. The phase camera was also used to help understand an output mode cleaner which was …
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Sensorless adaptive optics in advanced microscopy techniques
… performance at depth by pre-shaping the incoming wavefront with aberrations that are equal but opposite to those that degrade quality. The approach used in this work does not require the use of a wavefront sensor but instead the optimisation algorithm randomly alters the shape of the deformable …
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Long exposure point spread function estimation from solar adaptive optics loop data
… (AG) systems provide partial correction to wavefront distortions introduced by the Earth's atmosphere. They have become an essential tool to obtain diffraction-limited observations from ground-based telescopes. However, the AG correction is only partial and post-processing with a good …
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Point Spread Function Reconstruction for the Adaptive Optics System ALFA and its Application to Photometry
… of view. This estimate can be derived from the wavefront sensor (WFS) signals of the ALFA system. It was necessary to adapt an existing algorithm developed for curvature sensors to the Shack-Hartmann sensor (SHS) used on ALFA. The practicability and performance of this algorithm was then tested …
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On-Orbit Characterization of a Microelectromechanical Systems (MEMS) Deformable Mirror (DM): Mission Results from the Deformable Mirror Demonstration Mission (DeMi) CubeSat
… density of actuators to provide high precision wavefront control. This makes MEMS DMs a key technology for future space-based telescopes with adaptive optics for applications such as exoplanet direct imaging with coronagraphs. The DeMi payload design is a miniature space telescope with an …
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Detector Improvements and Optimization to Advance Gravitational-wave Astronomy
… I worked to develop and test a high-resolution wavefront sensor that employs a time-of-flight sensor. By achieving phase-locking between the demodulation signal for the time-of-flight sensor and the incident modulated laser beam, this camera is capable of sensing higher-order mode distortions of …
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Characterization of the atmospheric turbulence at the Sutherland site and conceptual design study and optimization of an Adaptive Optics system for the Southern African Large Telescope
… obtained with the Multi-Aperture Scintillation Sensor (MASS). Using the results from the site testing campaign along with the SALT optical design, I simulated the general dimensioning of a system for SALT that would use a single natural guide star (NGS). The trade-off between performances and …
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Phasing of Ground-based Optical Arrays for Space Applications
… reflected from the target complicate atmospheric wavefront sensing. To address these challenges, we propose a novel optical phased array architecture based on a combination of three techniques: (i) atmospheric phase is sensed using a distributed Shack-Hartmann Wavefront Sensor (SHWFS) using light …
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Improving nanosatellite capabilities for atmospheric sounding and characterization
… demonstrations for three kinds of atmospheric sensors: (i) passive microwave radiometers, (ii) atmospheric occultation experiments and (iii) coronagraphic direct imaging of exoplanets. Microwave radiometers (MWR) measure brightness temperatures in multiple channels across bands centered on …
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Liquid crystal photonic devices based on conductive polymers = Dispositivos fotónicos de cristal líquido basados en polímeros conductores
… MLCLs are obtained. Through a Hartmann- Shack wavefront sensor, the outcoming wavefront of the lenses are characterized. This characterization leads us to conclude that lenses with PEDOT:PSS as a high resistivity x ABSTRACT electrodes provide better lenses. Using identical electrodes, and …