利用数字全息干涉术测量电路板的连续弯曲形变

采用离轴菲涅耳数字全息干涉术实现了对电路板表面的连续弯曲形变测量。在电路板两端依次施加0.01mm至15mm位移载荷过程中,记录了1 501幅全息图。通过相邻两幅全息图数值重建的复振幅相位分布相减得到干涉相位差,根据相位差与离面位移的关系计算得到照明测量区域的离面位移,通过累加获得了施加1～15mm位移载荷时电路板表面的弯曲形变测量结果。由5块相同规格电路板上照明测量区域中同一电容中心点的离面位移,计算得到测量结果的A类不确定度不超过0.008mm,加载夹具引起的测量结果的B类不确定度为0.003 5mm,测量结果的合成不确定度不超过0.008 7mm。实验表明这种利用离轴菲涅耳数字全息干涉术测量物体大位移连续弯曲形变的方法具有良好的重复性和稳定性。

Measurement of continuous bending deformation for circuit boards by digital holographic interferometry

The measurement of continuous bending deformation for a circuit board surface was achieved by using digital off-axis Fresnel holographic interferometry. 1 501 holograms were recorded by applying a displacement load to both ends of the circuit board from 0 to 15 mm by the step of 0.01 mm.The interference phase difference was obtained by subtracting the complex amplitude phase distributions of two adjacent holograms with numerical reconstruction. Then, the out-of-plane displacement of the lighting measurement area was obtained according to the relationship between the phase difference and the out-of-plane displacement, and the measurement results were obtained by accumulating the bending deformation of the displacement load from 1 mm to 15 mm. By calculating the out-of-plane displacements of the same capacitor center in the lighting measurement area from five pieces of circuit boards with the same specifications, it indicates that the measurement results are no more than 0.008 mm for the type A uncertainty,no more than 0.003 5 mm for the type B uncertainty from a loading clamp and no more than 0.008 7 mm for the combined uncertainty. The results show that the method based on digital off-axis Fresnel holographic interferometry for measuring the continuous bending deformation of the object with a large displacement load has good repeatability and stability.