Abstract: A method for monitoring a laser welding process for welding workpieces by a welding laser beam is provided. The method includes, during the laser welding process, directing a measuring beam of an optical coherence tomograph onto an interaction area in which the welding laser beam interacts with the workpieces. The measuring beam penetrates the workpieces in the interaction area in a through weld of the workpieces. The measuring beam penetrating the workpieces is incident on a reference element. The method further includes acquiring measured values using the measuring beam, defining a first measured value range corresponding to detection of a material of the workpieces, defining a second measured value range corresponding to detection of the reference element, and determine a ratio of a number of measured values lying in the first measured value range and a number of measured values lying in the second measured value range.