SOAR Adaptive Module (SAM)


The SOAR Adaptive Module (SAM) will provide improved angular resolution in a relatively wide field at optical and infrared wavelengths by compensating selectively low-altitude turbulence.

The PSF metrics (FWHM, ellipticity, energy concentration and Strehl) depend on the wavelength, observing conditions and instrument parameters. The performance prediction for a representative set of conditions and wavelengths is given in this document [PDF] .

The picture on the right shows the SAM field. The nominal science field is 3'x3' square. Two tip-tilt natural guide stars (R>18mag) will be found on opposite sides of the science field, up to 2/5' distance from the center. The laser beam footprint (at nominal range of 10km) is shown by a blue circle at the center. PSFs are computed on at 5 locations in the field (empty circles) and compared to the un-corrected seeing-limited PSF, plotted at 2.5' distance.

The plots show various PSF metrics (FWHM, ellipticity, encircled enerdy in 0.3" diameter and gain of the central PSF intensity over seeing in magnitudes) for the wavelength of 0.7 micron. Full, dashed and dot-dashed lines correspond to the good (best 25%), typical (median) and 75% observing conditions. Object at zenith distance 45 degrees. The last points show metrics of the un-corrected PSF.