在附面层测量中，需对微小尺度的高速气流变化场进行瞬态测量。数字化的干涉测量方法能定量地解算出流场的密度场，是一种重要的应用。介绍了一种共路干涉的环路剪切干涉方法，对震动不敏感，无需参考面，适合附面层测量使用。采用基于空间位相调制的快速算法，配以脉冲激光器和同步控制系统，可实时地对扰流密度场进行定量测量。该系统采集分辨率200 pixels × 200 pixels，采集频率可达每秒1000帧以上。系统的波前重构方法经过计算机仿真，检测结果优于1/20λ。在0.6 m风洞对圆柱体尾部附面层进行测量试验，结果表明，在一定风速下，该系统能抑制振动干扰，显著地区分出圆柱体尾部扰流信号和振动噪声，具有良好的应用前景。

Transient measurements of high-speed airflow field are needed in the measurement of boundary layer. Digital interferometry can measure flow field quantitatively to obtain density information, which is very necessary in flow field measurement. In this paper, a common-path shearing interferometry method is introduced. It is insensitive to vibration and does not need a reference plane. It is suitable for flow field measurement. A fast algorithm based on spatial phase modulation, coupled with a pulse laser and a synchronous control system, is used to measure the disturbance density field quantitatively in real time. The acquisition resolution of the system is 200 pixels × 200 pixels, and the acquisition frequency can reach more than 1000 frames per second. The wavefront reconstruction method of the system has been simulated by computer, and the detection result is better than 1/20λ. The experimental results in a 0.6 m wind tunnel show that the system can restrain the vibration interference and distinguish the disturbance signal and the vibration noise remarkably. It has good application prospects.