Past investigations in the damage threshold of laser components have been of high interest within optics characterization. In view of the ever increasing complexity of optical components investigations in the LIDT require a more sophisticated adaptation of the measurement set-ups. The optimization of high power solid state laser systems led to the disc laser concept, which provides an increased output power. The achievable output power is mainly limited by the damage threshold of the coated and bonded crystal. Consequently, the understanding of damage mechanisms is a fundamental requirement for the disc laser optimization. It is assumed that the damage in disc laser crystals and deposited coatings can be traced back to the defects on the crystal surface or in the optical coatings. The expected size of the defects initiating laser damage ranges in the micrometer scale. In the present study, LIDT experiments are focused on the verification of this assumption and are intended to assist in the optimization of the manufacturing process. For a detection of the defects, an online defect inspection system was extended by a highly resolving imaging technique. The LIDT measurements have been performed on the basis of the Son1 protocol according to ISO 11254-2 at an effective pulse duration of about 11ns and a repetition rate of a few Hz at the wavelength 1.064nm.