The monitoring of the optics quality of DIMM instrument V. Kornilov, B. Safonov May 24, 2010 1 Intro duction A quantitative theory of measurement of optical turbulence (OT) with Differential Image Motion Monitor (DIMM) is based on certain priori assumptions [1]. ... Bottom: behavior of the instrumental Strehl's number for the left (triangle to the left) and right (triangle to the right) DIMM images during the period of measurement the maintenance of an additional correction factor seems superfluous. ...