基于条纹反射的非球面镜三维面形测量

Three-Dimensional Shape Measurement of Aspheric Mirror Based on Fringe Reflection

提出一种利用条纹反射原理测量非球面镜的新方法。测量过程中,利用液晶屏显示正弦条纹,由摄像机记录由待测镜面反射产生的条纹图。并将显示屏和摄像机分别沿待测镜面轴向移动。摄像机在每个移动位置上,记录下显示屏移动前后产生的两幅条纹图。通过相移方法,得到条纹图的相位信息后,对摄像机上每个象素点,能在待测镜面上找到一个对应待测点,并在获得该待测点的梯度信息的同时,获得该点位置坐标信息。最后通过积分,恢复待测镜面的三维高度信息。该方法不需辅助反射镜与干涉仪,能更加方便灵活地测量非球面镜。并且该方法有较好的抗噪性能,在噪声较大的情况下,仍能对非球面镜进行测量。模拟及初步实验均验证了该方法的可行性。

A new method to measure the three dimensional （3D） shape of the aspheric mirror is proposed. In the measurement, a liquid crystal display（LCD）screen displays the sine fringe pattern and a camera captures the deformed fringe pattern generated by the reflection of the mirror. And the screen and the camera are translated along the measured mirror axis, respectively. At each movement, the camera records the fringe patterns from the screen located at two different positions. By phase shifting technique, the phase information in the deformed fringe pattern can be gotten. Every camera pixel corresponds to a point on the tested mirror and its coordinate and slope can be determined. By integral processing, the 3D. shape of the measured mirror can be reconstructed. This method doesn＇ t need interferometer and assistant mirror. So it can reconstruct the tested mirror flexibly and cheaply. Moreover, this method owns strong ability of anti-noise. With large noise, this method also can reconstruct the 3D shape of aspheric mirror. Computer simulations and preliminary experiment validate the feasibility of this method.