The present disclosure relates to a method for characterizing a light source. The method includes providing a light source to be characterized, collecting light emitted from the light source by using imaging optics, the imaging optics generating a pupil of the collected light emitted from the light source, generating an image of a pupil of light emitted only from a first surface area of the light source at a detector using the imaging optics, laterally shifting the light source and the imaging optics relative to each other and after the lateral shift, generating an image of a pupil of light emitted only from a second surface area of the light source at the detector using the imaging optics. The imaging optics includes a field stop between the light source and the detector to select a portion of the light source's surface from which light is imaged at a time.