Zhongwu Wang, Xincheng Yao, Yusheng Zhao and David Schiferl
Los Alamos National Laboratory
z_wang@lanl.gov
We designed an optical lever to measure the temperature induced thermal displacement of solids, especially for nanocrystals. The sample and a knife-edge as a reference point are connected by a strip of aluminized mylar, which is served as a mirror. A Position Sensitive Photodiode (PSD) was used to record the deflection of the laser beam, which was induced by heating or cooling sample. Such a technique allows us to measure the temperature-induced displacement with the resolution of 1 nm. Furthermore, the Laser Polarized Sensitive Optical Coherence Topography (LPSOCT) was developed to measure the pressure induced phase transformation in Diamond Anvil Cell (DAC). A low coherence laser (SLD) was split to the two beams by an optical prism: one was focused on the sample, and another one was used as a reference. The interference signal between the reflected and reference beam was recorded by a fast photodiode, demodulated by a lock-in amplifier and continuously digitized by AID to computer. As the phase transition occurs, the variation of anistropic properties results in a significant change of the polarisity of the interference signal. Now we are testing several samples, and the preliminary results will be presented.