CHUN , Mark

Curvature sensing is a very simple and elegant method to measure the Laplacian of the wavefront, based on the conservation of flux irradiance. Its implementation does not require any special optical components and as it is a direct measure of intensity in defocused images, photodiodes or other read-noiseless detectors can be used. Because it is...

Self-generated turbulence and dome seeing are strong contributors to the degradation of astronomical image quality; besides the now infamous low wind effect, strange temporal power spectra, low (temporal) frequency turbulence, high (spatial) frequency turbulence and strong ground layer all point to local effects. Accounting for and including...

Image quality is sensitive to temperature fluctuations on the optical path, even if these are not fully developed turbulence. Thus, it's crucial to control the thermal environment, be it on a test bench in the laboratory, in instruments (e.g., entrance windows, near electronics), within domes and telescope structures. It is especially crucial...

Self-generated turbulence and dome seeing are strong contributors to the degradation of astronomical image quality; besides the now infamous low wind effect, strange temporal power spectra, low (temporal) frequency turbulence, high (spatial) frequency turbulence and strong ground layer all point to local effects. Accounting for and including...

Dome seeing is a known source of image quality degradation, but despite tremendous progress in wavefront control with the development of adaptive optics and environmental control through implementation of dome venting, surprisingly little is known about it quantitatively. We have found evidence of non-Kolmogorov dome turbulence from our...

Dome seeing is a known source of image quality degradation, but despite tremendous progress in wavefront control with the development of adaptive optics and environmental control through implementation of dome venting, surprisingly little is known about it quantitatively. We have found evidence of non-Kolmogorov dome turbulence from our...

Dome seeing is a known source of image quality degradation, but despite tremendous progress in wavefront control with the development of adaptive optics and environmental control through implementation of dome venting, surprisingly little is known about it quantitatively. We have found evidence of non-Kolmogorov dome turbulence from our...

International audience

Adaptive optics systems require a calibration procedure to operate, whether in closed loop or even more importantly in forward control. This calibration usually takes the form of an interaction matrix and is a measure of the response on the wavefront sensor to wavefront corrector stimulus. If this matrix is sufficiently well conditioned, it can...

By analyzing global covariance matrices from the imaka GLAO system at the UH 2.2m telescope, it is possible to reconstruct ground layer strength, the integrated turbulence strength as well as the vertical turbulence profile. These are compared to simultaneous profiles obtained by the Maunakea facility MASS/DIMM. A method has been developed to...