Study of real-time and precision measurement for 2-D deformation amounts of machine tool

为了开发出高性能的机床，需要对其在加工过程中的二维变形量进行测量，并将测量到的变形数据反馈给机床的设计工艺。因此，我们研究了机床二维变形量的实时、精确测量技术。我们已经开发了一种技术，通过它可以测量代表变形量的全场图像，而不需要相移技术。使用该技术，可以测量对象连续变形的变形量。但在阶梯状变形、不连续变形中，由于存在2π的模糊性，采用单波长激光的常规方法不能准确测量变形量。在这里，我们开发了一种新的技术，通过将上述技术与两个不同波长的激光相结合，可以测量包括阶跃变形在内的大变形。从一束多线的Ar激光中选择了488.0 nm和514.5 nm两束激光，然后分别引入两个声光调制器。这些声光调制器用作L/300s的快门。通过后，两束激光被耦合到单模光纤，并被传输到散斑干涉仪。物体变形后反射的光与参考光发生干涉，在重启重置模式下聚焦到摄像机的面阵上。该相机与声光快门同步工作，可以分别记录两个波长的散斑图，并以0.2ms的间隔交替聚焦在它们的CCD阵列上。根据散斑图的强度信号变化，利用先前开发的技术计算了每个波长的相位变化。最后，通过两个波长的相位差得到了包括阶梯状变形在内的大变形。

To develop a machine tool of high performance it is required to measure 2-D deformation amounts of it under : cutting process and then required to feedback the measured deformation data to design process of it Therefore, we studied real-time and precision measurement technique for 2-D deformation amounts of the machine tool. We had developed a technique by which a whole-field image representing the deforming amount can be measured without : phase shift techniques. Using this technique, deformation amounts of the object continuously deforming can be measured. But in step-like deformations, discontinuous deformation, usual techniques using a laser of single wavelength can not measure accurate deforming amounts, because of 2 π ambiguousties. Here, we developed a new technique, which can measure large deformations including step-like deformations, by combining the above technique with two laser beams of different wavelengths. From a multi-line beam of an argon laser 488.0nm and 514.5nm laser beams were selected and then separately introduced to two acoustic optical (AO) modulators. These AO modulators work as shutters of l/300s. After passing those, two laser beams were coupled to single-mode ; optical fibers and were conveyed to a speckle interferometer. The light reflected from the object deforming was interfered with the reference light and was focused on CCD array of the camera with the RESTART RESET mode. This camera synchronously working with the AO shutters can separately record two specklegrams which are of two wavelengths and are alternately focused on their CCD array with 0.2 ms interval. From the intensity signal changes ofspecklegrams, phase changes in each wavelength were calculated with the previously developed technique. Finally, large deformations including step-like deformations were obtained from phase differences in two wavelengths.