(Shack-Hartmann sensor)

A Shack-Hartmann sensor is a type of wavefront sensor. It consists of an array of lenses (called lenslets) of the same focal length. Each part of the wavefront (lenslet) is focused onto a photon sensor (CCD array). The local tilt of the wavefront across each lens can then be calculated from the position of the focal spot on the sensor. By sampling an array of lenslets all of these tilts can be measured and the whole wavefront approximated.

• We use a Shack-Hartmann sensor for fast absorption measurements (wavefront deformation due to local temperature increase) in optical materials.

• Alternatively the laser-induced deflection (LID) technique can be used.