the disclosure is an optical measuring system and the method thereof for precisely measuring physical characteristics of light emitted from waveguides , such as beam size , pattern , strength , focusing , collimation degree , and divergence angle , by means of a plane optical detector in which a plurality of pixels formed by a semiconductor fabrication process are arranged in an array , without specific measuring means . the light is incident into ends of the arrayed waveguides with uniform time intervals and emitted from the other ends of the waveguides to reach the optical detectors through which the physical characteristics of the light are obtained and defined arithmetically .