The study of damage mechanisms of millisecond lasers on position sensitive detectors

The photodetector, during operation, are particularly apt to damage when it is used under the laser irradiation. Position Sensitive Detectors are widely used owing to its high measurement accuracy, rapid response. In this study, the millisecond laser-induced damage in PSD was investigated. A mathematical model was established for millisecond pulsed laser heating of PSD. The transient temperature fields of PSD were obtained by using the finite element method. The time-resolved temperature is measured by an infrared radiation pyrometer. The numerical results are in good agreement with the experimental results. The results indicate that the PSD begins to damage due to the anti-reflective coating is removed and the aluminum electrode is melt at the laser energy density reaches 188 J/cm². For the laser energy density of 268 J/cm², the PSD is completely functionally damaged, due to the inner side of PMMA is totally thermal decomposited inducing a lot of carbon residue, blocked the incident detection laser, so the photoelectricity decrease to zero.