Optical System Design For Hard Disk Platter Surface Defect Inspection Device

Scattering theory indicates that light incidence on rough surface causes scattering phenomenon. The laser beam which emitted by using argon ion laser is shaped into oval light, irradiating to the surface of unmeasured disk. By analyzing the scattering and reflecti-ve lights which from the flaws of surfaces can be measured characteristics of the disk plat-ter surface.By studying scattering angle and scattering energy, this thesis discussed four kind of scattering models which were supported by Zemax. According to the roughness level of flaw surface in the hard disk, a reasonable scattering model was chosen to reflect the situ-ation of the surface. A testing optical system was designed.The size and position of flaw surfaces were found by analyzing the power which received by photo multiplier tubes and photoelectric position sensors.