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...

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...

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...

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...

International audience

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...

International audience

We are developing a new adaptive secondary mirror (ASM) for the University of Hawaii 2.2-meter telescope based on a novel and very efficient hybrid variable reluctance actuator developed by TNO. The actuator technology has broad implications on the ASM design and results in an ASM with a thicker facesheet, lower power dissipation, and simple...

TNO and industrial partners VDL ETG, L3Harris and Hyperion are developing a novel Adaptive Secondary Mirror (ASM) for Ground Layer Adaptive Optics (GLAO) at the University of Hawaii's 88-inch telescope on Mauna Kea. The ASM is based on a unique actuator principle which delivers a >30µm PV 99% linear stroke at a very high efficiency in terms of...

TNO and industrial partners are developing a new type of adaptive secondary mirrors (ASM) for the University of Hawaii 2.2-meter telescope, consisting of 210 actuators, in an overall volume of ø63cm by 15cm height, and having an aspherical convex mirror-shell of 3,5mm thickness. The novel actuator technology enables a compact system without...

Adaptive optics is an advanced technique developed for large telescopes. It turns out to be challenging for smaller telescopes (0.5~2m) due to the small isoplanatic angle, small subapertures and high correction speeds needed at visible wavelengths, requiring bright stars for guiding, severely limiting the sky coverage. The motivation to develop...

International audience

Adaptive optics is a technique mostly used on large telescopes. It turns out to be challenging for smaller telescopes (0.5~2m) due to the small isoplanatic angle, small subapertures and high correction speeds needed at visible wavelengths, requiring bright stars for guiding, severely limiting the sky coverage. NGS SCAO is ideal for planetary...

V(WF)²S: Very Wide Field WaveFront Sensor for GLAO

We performed closed-loop lab testing of large-format deformable mirrors (DMs) with hybrid variable reluctance actuators. TNO has been developing the hybrid variable reluctance actuators in support for a new generation of adaptive secondary mirrors (ASMs), which aim to be more robust and reliable. Compared to the voice coil actuators, this new...

We are developing an adaptive secondary mirror (ASM) that uses a new actuator technology created by the Netherlands Organization for Applied Scientific Research (TNO). The TNO hybrid variable reluctance actuators have more than an order of magnitude better efficiency over the traditional voice coil actuators that have been used on existing ASMs...

International audience