For the measurement of vertical profiles of sound speed in the sea using laser excited Brillouin scattering, a high resolution measurement of Brillouin frequency shift is required. In this work, a molecular absorption...For the measurement of vertical profiles of sound speed in the sea using laser excited Brillouin scattering, a high resolution measurement of Brillouin frequency shift is required. In this work, a molecular absorption cell was selected as the frequency shift discriminator and several kinds of absorption gases were tried. It was found that the strong line (#1095) of 127 I 2 at 18783.3297 cm -1 and two absorption lines of 129 I 2 located at the two sides of the #1095 line of 127 I 2 could be used as frequency shift discriminator to detect the changes of the Brillouin frequency shift. This selection is the best one within the range from 532.0131 nm to 532.5154 nm. But it is not perfect and there is a lot of work to do before its practical application.展开更多
文摘For the measurement of vertical profiles of sound speed in the sea using laser excited Brillouin scattering, a high resolution measurement of Brillouin frequency shift is required. In this work, a molecular absorption cell was selected as the frequency shift discriminator and several kinds of absorption gases were tried. It was found that the strong line (#1095) of 127 I 2 at 18783.3297 cm -1 and two absorption lines of 129 I 2 located at the two sides of the #1095 line of 127 I 2 could be used as frequency shift discriminator to detect the changes of the Brillouin frequency shift. This selection is the best one within the range from 532.0131 nm to 532.5154 nm. But it is not perfect and there is a lot of work to do before its practical application.
