X-ray microscopy by successive Fourier transformation II. An optical analogue experiment

An optical analogue experiment related to a method of X-ray microscopy by successive Fourier transformation is described. Some experimental design features are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/33445/1/0000848.pd

X-ray microscopy by successive fourier transformation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32040/1/0000083.pd

Testing, characterization, and control of a multi-axis high precision drive system for the Hobby-Eberle Telescope Wide Field Upgrade

A multi-axis, high precision drive system has been designed and developed for the Wide Field Upgrade to the Hobby-Eberly Telescope at McDonald Observatory. Design, performance and controls details will be of interest to designers of large scale, high precision robotic motion devices. The drive system positions the 20-ton star tracker to a precision of less than 5 microns along each axis and is capable of 4 meters of X/Y travel, 0.3 meters of hexapod actuator travel, and 46 degrees of rho rotation. The positioning accuracy of the new drive system is achieved through the use of high-precision drive hardware in addition to a meticulously tuned high-precision controller. A comprehensive understanding of the drive structure, disturbances, and drive behavior was necessary to develop the high-precision controller. Thorough testing has characterized manufacture defects, structural deflections, sensor error, and other parametric uncertainty. Positioning control through predictive algorithms that analytically compensate for measured disturbances has been developed as a result of drive testing and characterization. The drive structure and drive dynamics are described as well as key results discovered from testing and modeling. Controller techniques and development of the predictive algorithms are discussed. Performance results are included, illustrating recent performance of several axes of the drive system. This paper describes testing that occurred at the Center for Electromechanics in Austin Texas.Center for Electromechanic

Current status of the Hobby-Eberly Telescope wide field upgrade

The Hobby-Eberly Telescope (HET) is an innovative large telescope of 9.2 meter aperture, located in West Texas at the McDonald Observatory (MDO). The HET operates with a fixed segmented prima1y and has a tracker which moves the four-mirror corrector and prime focus instrument package to track the sidereal and non-sidereal motions of objects. A major upgrade of the HET is in progress that will increase the pupil size to 10 meters and the field of view to 22' by replacing the corrector, tracker and prime focus instrument package. In addition to suppo1iing the existing suite of instruments, this wide field upgrade will feed a revolutionary new integral field spectrograph called VIRUS, in support of the Hobby-Eberly Telescope Dark Energy Experiment (HETDEXx). This paper discusses the current status of this upgrade.Center for Electromechanic