为了准确测量残余应力的分布情况,提出一种基于反射式暗场白光数字全息的残余应力三维检测技术。该技术将激光损伤点附近区域沿着轴向以数值化的形式离散成多层,每层的暗场反射光强度正比于该层光学双折射的轴向梯度,因此利用白光数字全息测量每层暗场反射光强度,即可结合光弹效应重建各层的剪切应力。通过对激光损伤的熔石英玻璃测量,实际验证所提技术可以对样品的三维残余应力分布进行准确重建,且轴向分辨率可达10 μm。实验结果表明,所提技术可以提高加工工艺和衡量产品的质量。

To accurately measure the residual stress distribution, a reflective dark-field white light digital holography-based three-dimensional (3D) residual stress detection technology is proposed herein. This technology discretizes the area near the laser damage point into multiple layers in a numerical manner along the axis. The intensity of the dark-field reflected light of each layer is proportional to the axial gradient of the optical birefringence of the layer. Therefore, white-light digital holography is used to measure each layer. By measuring the reflected light intensity of each layer dark field with white light digital holography, the shear stress of each layer can be reconstructed by combining the photoelastic effect. Through the measurement of laser-damaged fused silica glass, it is verified that the proposed technique can accurately reconstruct the three-dimensional residual stress distribution of the sample, and the axial resolution can reach 10 μm. Experimental results show that the proposed technology can improve processing technology and also measure the quality of products.