The exponential fitting of optical threshold and analyses of testing errors

The effect of irradiated spot size and number of sites exposed for each pulse energy or power density on damage possibility is studied. It is shown that larger irradiating spot size and more sites tested for each pulse energy or power density, more accurate damage data could be obtained. Also the effect of defect distribution should be taken into account and it also affects the accuracy of damage threshold determination. A new method, exponential fitting, is described and it yields more accurate damage onset. And it is derived from but suitable to more than all-degeneration model.