基于自动聚焦技术的三维测量方法研究

Research on 3D Measurement Method Based on Autofocusing Technology

在半导体加工检测微机电系统(MEMS)组装.生物医学航空航天、量子通信等领域,微结构元器件的应用越来越广泛。要实现微结构元器件的高精度加工,必须建立相应的高精度测量方法。针对微小物体三维形貌测量,提出了一种基于自动聚焦技术的三,维测量方法。详述了该方法的测量流程。使用单相机对被测物进行垂直扫描并采集图像序列;通过对序列图像逐一进行清晰度评价计算,依靠精确的聚焦判定确定表面点的高度;通过二维水平扫描测量,获取表面三维轮廓数据。根据所阐述的测量原理,聚焦判定决定了测量精度。通过研究,提出了改进的清晰度评价算法,将改进的Retinex算法与Tenengrad梯度函数相结合,提高了测量方法的适用性和稳定性。利用标准量块台阶进行了精度验证试验,所提方法测量精度优于15μm。该研究为微结构元器件三维形貌测量提供了一种低成本、较高精度的测量方法。

The application of micro-structured components is becoming more and more extensive in many fields,such as semiconductor processing and testing,micro electro mechanical system(MEMS)assembly,biomedicine,aerospace,quantum communication,etc.In order to realize high-precision machining of micro-structure components,the corresponding high-precision measurement method should be established.A 3D measurement method based on autpfocusing technology was proposed for 3D shape measurement of small objects.The measurement process of this method was described in detail.By using a single camera,an image sequence of the object surface could be acquired during vertical scanning.Each image in the sequence should be processed by sharpness evaluation method to confirm the focusing position.Rely on the precise focusing position determination,the height of the surface point could be obtained.Then the 3D surface profile data could be gathered through 2D horizontal scanning.According to the proposed method,the measurement accuracy depends on the focusing evaluation.A modified sharpness evaluation algorithm was proposed by combining the improved Retinex algorithm with Tenengrad gradient function to enhance the applicability and stability of the method.The accuracy verification experiments were carried out using standard gauge blocks stage.The result proved that the measurement accuracy of the proposed method was better than 15 um.It provides a low-cost and high-precision measurement method for 3D morphology measurement of micro-structure components.