Quality control and the respective metrology play a vital role in supplying the thin film optics for next generation photonic devices. This includes in-situ and ex-situ measurement techniques to make sure specifications are met and possible mitigation strategies can be designed to react possibly even online to instabilities or control them. In general, many applications require accuracy levels in the verification of specifications that definitely can only be reached in high precision measurement systems. Specifically, optical losses or laser-induced damage threshold and precise surface conditions are characterized in specific and standardized procedures. This webinar will give an overview on metrology for precise and standardized quality control as well as process stability. Examples for sensitivities of the presented measurement techniques are discussed and capabilities of the community are summarized.