Caltech Astronomy

Caltech Optical Observatories

Optical/Infrared Instrumentation


Palomar Laser Guide Star System Performance

The Strehl achieved by the LGS-AO system can be decomposed into three terms, the product of which is the expected Strehl on the science target.

  • High-order LGS Strehl: This is a function of laser power, atmospheric sodium density, laser spot size, seeing, and telescope elevation.
  • Tip/tilt Strehl: This is a function of seeing and tip/tilt object magnitude.
  • Tip/tilt anisoplanatism Strehl: This is a function of the distance between the til/tilt object and the science target, and the seeing.

Each of these terms can be estimated for the K band from the graphs on the left, for various assumptions about improvements in the laser power and low-order wavefront sensor performance. These predictions are based on a very limited set of data taken during our engineering night on 9/8/06.

In this regime, the H band Strehl will be approximately 1/2 that at K band.


K strehl = 22% LGS PSF (FWHM=0.115")

For more information please contact abouchez@astro.caltech.edu.