一种大视场相位测量轮廓术系统标定方法

New Method for System Calibration in Phase Measurement Profilometry with Large View Field

在进行大视场相位测量轮廓术系统参量标定时需要大的标定平面和精密移动台,由于携带不方便,不易进行现场标定。提出了一种用于相位测量轮廓术系统参量的高精度、现场标定方法,采用一块较小的平面标定靶在有效测量体积内不同位置多次摆放,以获取密集的数据点。先标定出摄像机的内参量和外参量,再指定一个全局参考平面和若干辅助参考平面,然后在图像平面上分区计算出每个位置标定靶上每点相对辅助参考平面的高度差和相位差,最后应用极大似然估计法估计出相位高度映射参量。实验中平面高度测量的标准偏差达到0.0433 mm。这种方法只需要较小的平面标定靶,标定过程方便、精度高,完全适合大视场三维测量相位测量轮廓术系统现场标定要求。

A standard plane with large area and a precision moving stage are required to calibrate the parameters for the phase measurement profilometry （PMP） system in large view field. It does not suite on-line calibration because of the discommodity to tote the required plane and stage. A new method for on-line calibrating the parameters of PMP system accurately is introduced to solve this problem. An undersize calibrating plane is placed at several positions in available measurement volume randomly to acquire dense data points. The inner and external parameters of camera are estimated with the method used in photogrammetry. A global reference plane and several assistant planes are appointed. And then, the differences of height and phase in every tested position between the plane and their corresponding reference plane are calculated in division. Finally, the parameters of phase-height mapping are estimated with maximum likelihood estimate. In experiment the standard diviation of plane height measurement reaches 0. 0433 mm. This method is suitable for calibrating the PMP system with large view field because only a small standard plane is required , the calibrating procedure is convenient and the result is highly accurate.