Algorithm for monitoring long-term instability of laser writing systems DOE by analyzing the diffraction efficiency of 2D diffractive sensor elements

The results of the development of an algorithm for monitoring long-term instability of scanning laser writing systems in the manufacture of diffractive optical elements are presented. To implement the proposed algorithm, special microgratings of two types (2D calibration diffractive marks (2D-CDM) and 2D diffractive sensor elements (2D-DSE)) are built into the working structure of the element, and control is carried out by analyzing the diffraction efficiency of these structures. It is shown that to control the long-term instability of the coordinates of the diffraction zones formed on the substrate, as well as the height and duty cycle of the written structures, it is sufficient to measure 5 diffraction orders for 2D-CDM and for 2D-DSE. An algorithm for writing embedded 2D microgratings and analyzing the measured values of their diffraction efficiency is presented to obtain the corresponding data on errors in writing the working structure of the DOE.