基于数字散斑剪切干涉术的三维面型测试

3D Shape Measurement Based on Digital Speckle Shearing Interferometry

摘要:

基于数字散斑剪切干涉术的原理, 研究了物体面型的三维测试技术。使用倾斜反射镜的方法, 使物光束散斑场偏转,再由CCD记录偏转前和后物光束的散斑场。这种方法代替了传统的使用剪切元件空间上直接获得干涉条纹图, 减少了由于剪切元件分束引起的物光束的光能损失, 实现了数字散斑剪切干涉术测量物体面型。应用MATLAB软件编程, 控制剪切散斑干涉图的精确定向平移, 得到了4个干涉图, 实现了数字四步相移, 代替了传统的在参考光中利用位相控制器的机械相移, 从而实现了物体面型的三维测试。该方法不仅省去传统剪切散斑干涉术中需要对感光胶片进行化学湿处理的过程, 也省去了压电位移器等硬件。大量的实验表明, 该方法不仅简化了测试光学系统和实验的过程, 也提高了测试精度, 其精度可达到1/10波长。

Abstract:

Based on the principles of digital speckle shearing interferometry, the technique for measuring 3D shape of an object was studied. For the method, the speckle field of the object light beam was deflected by inclining mirror and the speckle fields before and after mirror inclining were recorded by CCD. It substituted traditional special interference fringe obtained directly by using shearing element and reduced the energy loss of the object light beam caused by shearing element. MATLAB software was used to make precise control on the parallel and directional shifting of the speckle shearing interference fringes, then 4 interferograms were obtained and four-step digital phase shifting was realized. Traditional mechanical shifting technology with phase controller in reference light beam was substituted and 3D shape measurement was realized. This method omitted the chemical processing of photographic film, and hardwares such as piezoelectric translator were unnecessary. Experimental results show that not only the testing system and experimental process are simplified, but the measurement precision is improved to be up to 1/10 wavelength.