Scratches on optical component surface and its’ modulation on injecting laser

Surface damage of optical components is the main cause of lowering the laser-induced damage threshold. Surface scratches are observed exactly, and are divided into three kinds, namely, one scratch, two scratches and multi-scratches. By the method of Finite Difference Time Domain(FDTD), the intensity distribution around the surface scratches was numerically simulated on the basis of a common semicircle scratch with a half wavelength diameter. The graph of the maximal value of light intensity versus distance between scratches is got. It is concluded that optical damage is easily induced by scratches on the rear surface than those on the front surface. It also shows that in the case of multi-scratches, the maximum light intensity varies periodically with the increase of the distance between s