What is the precision of FrontSurfer wavefront sensor?

Typical configuration of the FrontSurfer wavefront sensor has a precision of about λ/60 PV (for λ=0.63 µm) in the reference mode and about λ/6 PV in the absolute measurement mode.

In the reference mode, the precision is mainly limited by the image sensornoise and can be improved by averaging over multiple frames and using a microlens array with larger focal distance. In the absolute measurement mode, the precision is limited by fabrication errors of the microlens array (or Hartmann mask).

Please note that the precision is specified for low-order aberrations, when the sampling error can be neglected. It is important that the microlens array (or Hartmann mask) provide sufficient sampling for the aberrations to be measured.