Development of rho-optical spectroscopy by means of ultrasound difrtaction

本研究的目的是研制一种利用超声衍射现象在高频范围内测量流变光学系数的装置。测量一阶衍射光的偏振参数，方位角和相位延迟的变化，给出了折射率的复各向异性正弦响应与超声引起的同位素响应之比的信息。这里我们解释一下复杂反应的含义。各向异性的正弦响应与各向同性的一个相位同相称为真实的响应，而与各向同性的相位相差90度的正弦响应称为虚响应。我们将de Gennes的振动-再取向耦合公式应用于超声色散关系，修正了复响应理论。利用该公式，我们可以用流体双折射和再取向弛豫时间的数据，将实验结果与理论结果进行比较， ...更多信息 在亚磷酸三苯酯（TPP）和液晶各向同性相4-氰基-4'-戊基联苯（5CB）中进行了实验。前者不显示频率相关响应，并且仅检测到虚响应。这是由于重取向弛豫时间远大于超声波频率的弛豫时间。在5CB的情况下，不仅观察到虚的而且观察到真实的响应。这是由于再取向弛豫频率与本研究中使用的超声频率（5 - 25MHz）相当。由偏振测量得到的复谱与我们用流体双折射值和再取向弛豫时间值修正的理论符合得很好，在较高的频率下，衍射光的强度很小。所以我们必须提高仪器的灵敏度。在2007年的研究中，我们采用光电倍增管作为检测设备，而不是光电二极管。这使我们能够测量低超声强度测量，并使偏振参数的分析非常简单。测量可以在Raman-Nath参数约为0.1时进行。这一成功对未来更高频率范围内的测量有希望。

The purpose of this study is to develop an apparatus to measure rheo-optical coefficient in the high frequency range using the ultrasound diffraction phenomena Measurement of the polarization parameters, change in azimuth angle and phase retardation, of first order diffracted light give information of ratio of complex anis: tropic sinusoidal response in the refractive indices to the isotopic response one caused the ultrasound. Here we explain what complex response means. The anisotropic sinusoidal response is in phase to isotropic one phase is called a real response while the sinusoidal response which differs by 90 degree from isotropic one in phase is called imaginary response. We have modified the theory of complex responses using de Gennes' translational-reorientational coupling formula applying to ultrasound dispersion relation. Using this formula, we can compare the experiential results with the theory using the data of flow birefringence and reorientational relaxation time.We car … More ried out the experiment in triphenylphosphite (TPP) and isotropic phase of liquid crystal, 4-cyano-4'-pentylbiphenyl (5CB). The former does not show the frequency dependent response and only imaginary responses are detected. Those are due to the reorientational-relaxation time is much larger that that of ultrasonic frequency. In case of 5CB, not only imaginary but also real responses were observed. Those are due to the reorientational relaxation frequencies are comparable to ultrasonic frequencies (5-25MHz) used in this study. The complex spectra obtained from polarization measurements fairly are good agreement with our modified theory using the values of flow birefringence and reorientational relaxation time.In higher frequencies, the intensity of diffracted light is to be small. So we have to improve the sensitivity of our apparatus. In the studies in 2007, we adapted a photomultiplier as a detection device instead of photodiode. This enables us to measure the low ultrasound intensity measurements and that enable the analysis of polarization parameter quite simple. The measurement can be carried out at the Raman-Nath parameter is about 0.1. This success is promising to the future measurements in higher frequency range Less