Detecting Method of Bulk Defects in DLC Films Using Light Scattering

Diamond-like carbon (DLC) film has various micro-size defects like pinhole, void and particle. When DLC film is exposed to white light, light is scattered in all direction at defects in DLC film. In this paper, defects in DLC film are detected by observing scattering light from defects under dark-field microscope. DLC film has wavelength dependence of transmittance. Therefore, using its wavelength dependence allows to separate surface and inside defects of DLC film. This paper describes development of bulk defects detecting system using optical filtering and scattering light detecting. Bulk defects of DLC films were successfully separated into surface defects and inside defects. This detecting method of defect is nondestructive and easy, and applicable to DLC films as well as other coating films.