Diffraction-limited imaging with ground-based optical telescopes

Diffraction-limited Imaging with Ground-based Optical Telescopes

The construction of diffraction-limited images with ground-based optical telescopes by means of closure-phase observations is explored. The effect of redundant baselines on closure-phase observations is analyzed, and it is shown that for bright objects a nonredundant-mask approach is superior to the use of the full aperture. Observations of closure phase with a nonredundant mask on the 200 in. ...

Optical vortex coronagraphs on ground-based telescopes

The optical vortex coronagraph is potentially a remarkably effective device, at least for an ideal unobstructed telescope. Most groundbased telescopes however suffer from central obscuration and also have to operate through the aberrations of the turbulent atmosphere. This note analyzes the performance of the optical vortex in these circumstances and compares to some other designs, showing that...

New Generation Ground-Based Optical/Infrared Telescopes

Sub-diffraction-limited optical imaging with a silver superlens.

Recent theory has predicted a superlens that is capable of producing sub-diffraction-limited images. This superlens would allow the recovery of evanescent waves in an image via the excitation of surface plasmons. Using silver as a natural optical superlens, we demonstrated sub-diffraction-limited imaging with 60-nanometer half-pitch resolution, or one-sixth of the illumination wavelength. By pr...

Diffraction-limited 800nm imaging with the 2.56m Nordic Optical Telescope

A quantitative assessment is presented of diffraction-limited stellar images with Strehl ratios of 0.250.30 obtained by selection of short-exposure CCD images of stars brighter than +6m at 810nm with the Nordic