Automatic digital optical heterodyne phase locking loop in the milliradian domain for spaceborne laser interferometry.

We developed a digital optical phase locking loop (OPLL) with three advantages, including high precision of phase locking, high control bandwidth up to 2.8 MHz, and automatic laser locking strategy. Spaceborne laser interferometers will be used to measure tiny displacements caused by gravitational waves in millions of kilometers range. A slave laser will be heterodyne phase locked to the incoming weak light at the end of an arm, emitting a higher power light back to the other satellite to measure pathlength variations at the picometer level. Such accuracy requires extremely precise OPLL. We report an experiment to demonstrate a digital OPLL that can automatically lock two independent free-running Nd:YAG lasers with residual phase error below 1mrad/Hz above 0.01 Hz, which is the best performance recorded for digital servos, to our knowledge. Such performance tested under a normal laboratory environment will be highly improved in a vacuum environment with temperature and vibration well controlled. Both the digital OPLL and the automatic strategy were implemented on a field programmable gate array that could be potentially used for future gravitational-wave detection. Our experiment might change the thinking of scientists who study phasemeters of gravitational-wave detection because we are aware that the digital phase locking loop used for "optical phase tracking" is differently designed from "optical phase locking."

[Raman spectra of murine skin irradiated by high power millimeter wave].

An experimental study on Raman spectroscopy of normal murine skin and the skin irradiated by high power millimeter wave (HPMM) is presented. It is showed that the Raman spectra of normal skin mainly originate from collagen, and the characteristic peaks are 857, 936 and 1 658 cm(-1). The result showed that after irradiation by HPMM, the relative intensity of the characteristic peaks at 857 and 936 cm(-1) of Raman spectra was decreased. This meant that the collagen was destroyed and even daimaged. It was probably indicated that the skin tissue was damaged and could not be restored. The result also showed that the intensity of the characteristic peak at 1658 cm(-1) of the skin tissue irradiated by millimeter wave with the duration of 20 s decreased. It was considered that the protein in the skin was destroyed. Those results were consistent with macroscopic observation results.

[Study on the EMF-temperature co-effects on protein conformation by fluorometry].

The bioelectromagnetic effects are wildly concerned for a long time, and related researches are conducted in all kinds of directions in recent years. The EMF-temperature co-effects are more interesting nowadays. By studying the effects of EMF co-operated with temperature on a protein, an irreversible protein denaturation is found under the processing of EMF, and this denaturation is also Arrhenius-rule-obeyed. In addition, a protein denaturation model under the EMF-temperature co-effects is built. In this paper the EMF-temperature co-effects are explained in a way of molecular reacting kinetics, and the athermal effects of EMF are also discussed to some degree.