In addition to linear reflectivity and ultra-fast 2D displacement interferometry, we developed a melting diagnostics based on the non-linear optical technique of third harmonic generation (THG) using a circularly polarized laser pulse. This diagnostic resolves the less than 300 fs melting transition of laser excited Si and GaAs, and it also detects a response in shock compressed silicon. Our results show that Si remains crystalline during compression of an elastic 100 kbar shock wave. Results from Si shocked to higher pressures (g 300 kbar) indicate a decrease in THG, suggesting some level of disordering or unexplained phase change.Install the 1a aluminum mirror just outside the 3I window, and steer the HeNe beam onto the face of a CCD camera that you place in the nearby holder. Install ... Attenuate the THOR laser by adjusting the delay of the PRO Q-switches. ... If the energy is too high (you can see the beam on an IR card), it will burn the objective.
|Title||:||Experimental Studies of High Energy Density Silicon Using Ultra-fast Lasers|
|Author||:||Will Robert Grigsby|
|Publisher||:||ProQuest - 2007|