Fully Computerized Multi-Pass Fabry-Perot Interferometer for Rayleigh-Brillouin Scattering Experiments

摘要

The development of a Multipass Fabry-Perot interforometer assembly for use in Rayleigh-Brillouin scattering experiments is reported. The optical alignment and the scattered signal data acquisition have been completely computerized. Digital scanning and alignment strategies of the Fabry-Perot resonator have been incorporated, which makes this instrument quite unique in this respect. The high contrast (--10/sup 10/) and finesse (--50) offered by this instrument makes it possible to detect Brillouin peaks from samples that have a small Brillouin scattering cross-section. As part of this system a compatible and precision sample chamber has been constructed, which has been designed to operate in the pressure and temperature ranges of 1-1000B and 20-150/deg/C, respectively. The cell has been constructed to be small and compact, but it still has a large heat capacity (--250J/K) which ensures easy and stable temperature control of the liquid sample volume which has a size of 40 mm/sup 3/. The achievable temperature stability is +-1mK and +-2mK for operating temperatures below and above 100/sup o/C, respectively. The pressure stability is in the range of +-0.05B of the set pressure for pressures below 100B and it is +-0.05% for higher pressures up to 1000B. Both pressure and temperature are remotely monitored and controlled by a ND/100 computer. Special care has been taken in designing the optics of the pressure cell to ensure that both the primary and secondary reflections from the entrance window, as well as the main beam, go out of the scattering region in order to achieve higher signal-to-noise ratio in actual experiments. (ERA citation 12:048288)