微小孔尺寸形状的脱模与图像测量

摘要

A measuring method was presented that combines mold extraction and image processing to measure the internal geometry of micro holes.Adopting vinyl polysiloxane of hyperelasticity as mold material,the internal form of micro holes was copied as the external form of the mold by mold extraction method.By taking photos of the mold through microscope and utilizing image processing means,such as image segmentation,border tracing and line detection,a curve showing the variation of internal diameter of micro hole with hole depth was obtained.A measuring software was developed for the measurement of size and profile of micro holes in combination with mold extraction.The copy accuracy of the mold by mold extraction method was tested by the software,and for micro holes whose diameter varies from 145 μm to 155 μm,the average absolute error between the molds and original holes at the end was 0.9 μm.An internal mold of a three-dimensional cavity was made to obtain the average absolute error between the mold and cavity of 0.37 μm and the root mean square error of 0.51 μm.Combining mold extraction and image processing,the method can be used to measure the diameter and internal geometry of micro holes.%将脱模方法与显微图像处理结合,实现了微小孔内部轮廓的尺寸形状测量.首先采用具有超弹性的乙烯基聚硅氧烷作为制模材料,通过脱模方法将微小孔内部轮廓复制为模型的外部轮廓.然后在显微镜上采集模型的放大图像,利用图像分割、边缘提取、直线检测等图像处理手段,测量出微小孔内部直径随深度的变化曲线.开发出用于测量微小孔尺寸形状的应用软件,利用该软件对脱模法的复制精度进行校验.对于孔口直径在145 ～ 155 μm的微孔,所制模型在孔口处直径与原始孔口直径的平均绝对值误差为0.9 μm.通过脱模方法制作三维型腔模型,得到脱模模型形貌与原始形貌的平均绝对值误差为0.37 μm,均方根误差为0.51 μm.所提方法融合微米量级的脱模精度和像素级的图像测量精度,可用于微小孔孔径、内部轮廓形状等的测量.