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Damage Effects and Mechanisms Research of Femtosecond Laser on CCD

Author: WangMing
Tutor: WangTingFeng
School: Graduate Schoo,Chinese Academy of Sciences
Course: Optical Engineering
Keywords: fs pulse laser damage threshold CCD damaging mechanism
CLC: TN386.5
Type: Master's thesis
Year: 2012
Downloads: 22
Quote: 0
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Abstract

Charge coupled device (CCD) has been widely used in many civil and military field. The photoelectric equipment, with the CCD detector as the core optical equipment be extremely vulnerable to disturbance and damage of the laser. Therefore,the interaction of the laser and CCD detector has been a focal point in the study of laser applications. In recent years, with the development of laser technology and the femtosecond laser atmospheric transmission, researchers start to pay attention to the femtosecond laser disturbance and damage effects on the CCD. Carrying out the study on damage effects and mechanisms of CCD irradiated by femtosecond laser has important theoretical value on understanding the interaction of ultra short pulse laser and material. In this thesis, the damage effects and mechanisms of CCD irradiated by femtosecond laser were studied. A800nm,500μJ,100fs laser pulse was used to radiate interline CCD solid-state image sensor in the experiment. The phenomenon of the point damage, the line damage and the whole target surface damage are observed while we are increasing the energy during the experiment. At the same time, we also obtained those damage thresholds:151.2mJ/cm2,508.2mJ/cm2and5.91J/cm2。In the different damage situation of CCD, we measure the resistance values between the clock signal lines, and measure the resistance values between the clock signal line and the ground. By means of contrasting the resistance values of the CCD before and after the damage, we find that:point damage do not make the resistance change, the other parts can still be imaging except the part of injury, through observing the surface of the CCD, we can conclude that the point damage only destroyed the damaged pixel. We can find that the resistance between the vertical clock signal lines, and between the vertical clock signal line and ground of the line damage CCD decrease significantly, the remainder can still imaging except the white line, and through observing the surface of CCD, we can conclude that line damage only destroyed the damage pixel and the charge transfer circuit. The whole target surface damage can also bring about the resistance between the vertical clock signal lines, and between the vertical clock signal line and ground decreased significantly. It indicates that the vertical transfer charge circuits appeared short circuit under the damage pixel were destroyed. Through observing the surface of CCD, we can see that the damage extent is more serious than line damage, the entire CCD charge storage and transfer cannot be completed normally, therefore, the CCD cannot imaging normally.

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