Study On The Thermal Stress Of Millisecond Pulsed Laser Irradiation CCD Image Detectors

The research of damage mechanism of long pulse laser irradiation CCD detector had been studied in this paper. Based on the theory of heat conduction and thermal elastic mechanics, the physical model of millisecond pulsed laser irradiate CCD with multi pixel array structure was established. In the model it was been assumed that the material is isotropic, thermal and mechanical material parameters are changing with temperature. The melting phase transition process of aluminum electrode material had been considered with the equivalent specific heat method. The heat conduction equation and stress balance equation had been solved with the finite element. Through repeated research and coordinate the relationship between the time step and the mesh generation, the transient temperature field and stress field of material before and after melting had been obtained.According to the simulation conditions, the experiment which millisecond pulsed laser irradiated the color CCD had been established. The power density of laser been constantly raised in the experiment but spot size unchanged. The image was observed in proper order which captured by CCD, that the linear working state,crosstalk, no signal output of the light area internal photosensitive unit, Until CCD camera was damaged completely in the final. The damage mechanism of millisecond pulsed laser irradiated CCD detector was given.Final, the Raman spectra of silicon material were measured by a micr-Raman spectrometer to judge the stress of CCD chip.The Raman frequency shift of silicon materials in CCD was obtained, and the stress distribution was analysed in the process of laser irradiation.