干涉角度显微测量提高光子相关法空气声声压测量精度研究

在光子相关法测量自由场空气声声压中,光束夹角的准确测量影响着测量声压结果。提出了采用显微放大成像方法,利用CCD测量干涉区条纹间距,从而得到更为精确的光束夹角。首先,通过仿真分析高斯光束干涉条纹间距均匀性对光束夹角测量的影响,优化了声场测量的光路结构;然后,使用标准分辨率板对CCD显微成像的放大倍率进行标定并实现了干涉角度测量;最后,构建了光子相关法自由场空气声声压测量的实验系统。实验结果表明,相比于测量光的空间传播距离等传统三角方法获得的光束夹角,该方法得到的光束夹角提高了空气声声压测量的精度。

Research on Improving the Accuracy of Measuring Acoustic Pressure by Photon Correlation Spectroscopy Based on Interference Angle Microscopy

In the experiment of measuring air-borne sound pressure by photon correlation spectroscopy in free field, the accurate measurement of the angle between two beams has a great influence on the result of sound pressure measurement. By using the magnified imaging of the microscopic objective, the fringe spacing in the interference area is measured and the angle between the two beams is calculated with high accuracy. Firstly, the influence of the interference spot shape and the uniformity of the fringe spacing on the sound pressure measurement is studied to optimize the optical configuration. Then, the USAF test target is employed as the sample to calibrate the amplification factor of the system. Finally, the air-borne sound pressure in free field is measured by the photon correlation technology. The experimental results showed that, compared with the angle obtained by traditional tri-angle method by measuring the spatial propagation distance of light, the angle obtained by this method improved the accuracy of air acoustic pressure measurement.