一种弱超声驻波光栅相位振幅定量测量方法

A method for quantitative measurement of phase amplitude of weak ultrasonic standing grating

基于共轴相衬干涉原理,提出了一种定量测量弱超声驻波相位光栅相位振幅的方法,并构建了一套超声光栅相位快速测量与成像实验系统。分析了相衬干涉定量相位成像与测量原理,通过拍摄1幅或2幅弱超声驻波光栅的相衬干涉图,就能反演得到其定量相位分布,求得相位振幅。为提高相位测量精度,分析了相衬成像中像衬比度与相板相位延迟量的关系,从而得到了相板最佳相位延迟量的选取条件。实验获得弱驻波超声光栅相位振幅与驱动电压的关系,与其他方法得到的结果基本一致,证明了本文方法定量测量弱超声驻波光栅相位振幅的可行性与可靠性,测量相位振幅误差约为0.003rad。将本文方法应用于对普通全息相位光栅进行定量相位测量,进一步验证了方法的准确性,也说明了本文方法同样适用于其他弱相位物体的快速定量成像与测量。

Based on the principle of Zernike＇s phase contrast interferometry, a method for quantitative measurement of phase amplitude of weak ultrasonic standing grating is proposed and an experimental system for fast phase measurement and imaging of weak ultrasonic standing grating quantitatively is es- tablished. The principle of quantitative phase contrast interference imaging and measurement is analyzed. The phase amplitude of weak ultrasonic standing grating can be obtained from the quantitative phase dis- tributions of the phase grating reconstructed by shooting single or two phase contrast interferograms. In order to promote the accuracy of measurement, the relation between image contrast and phase retarda- tion of phase plates is discussed,so that the optimal selection for phase retardation of phase plate can be obtained. The similar experimental relations between phase amplitude of weak ultrasonic standing grating and driving voltage obtained by the proposed method and another method demonstrate its reliability and feasibility. The phase measuring error is around 0. 003 rad. The proposed method is also applied for quantitative imaging and measurement of a holographic phase grating to test and verify its precision fur- ther,which reveals its applicability for fast quantitative imaging and measurement of other weak phase objects.