Development of Head Flying Height Measuring Apparatus Using Image Processing

研制了一种基于迈克尔逊激光干涉测量的新型磁碟间距测量系统。该系统由干涉光学仪器、高分辨率（2亿像素）图像采集装置、条纹跟踪机构/电路和磁盘旋转机构四个子系统组成。高视觉图像处理可在Window系统和多条纹跟踪技术上操作，具有高再现性和高精度。下面的条纹是干涉光束分为两束的方式：一束用于CCD，另一束用于PSD（位置敏感探测器）。PSD的输出应用于PZT致动器导出参考镜，使CCD上的条纹保持固定位置。利用该系统，成功地阐明了接触式头滑块起动时的动态特性。其次，对条纹跟踪技术进行了二值化处理，以确定条纹的位置和倾斜度以及条纹之间的位置和间距两个参数。在该技术中，参考镜和压电陶瓷作动器被分为两组，一组用于平行位移，另一组用于俯仰倾角。这使我们能够更准确地固定条纹图像，从而在多次图像处理后精确提取脊线。最后，利用psd的输出信号是目标平面运动的反射，将多重条纹跟踪技术扩展到目标平面二维姿态的在线测量。

A novel head-disk spacing measurement system based on Michelson laser interferometry has been developed. This system was comprised of four kinds of sub-systems: interference optical instrument, high-vision (200 million pixels) image capturing device, fringe following mechanism/circuits and disk rotation mechanism. Image processing for high-vision image operable on the Window system and a multiple fringe following technique permitted high reproducibility and high accuracy. The fringe following is the way in which interference light beam is divided into two beams: one is for CCD and the other is for PSD (Position Sensitive Detector). The output of PSD is applied to a PZT actuator to derive a reference mirror such that the fringe on CCD maintains a fixed position. Using this system, dynamic behavior of a contact-type head slider while starting was successfully clarified. Next, the fringe following technique was dualized in order to fix two fringe parameters, the position and inclination of the fringe, or the position and interval between the fringes. In this technique, the reference mirror and PZT actuator were separated into two sets, one is for parallel displacement and the other is for pitching inclination. This enabled us to fix the fringe image more accurately and thus followed to accurate ridgeline extraction after multiple image processings. Finally, the multiple fringe following technique were extended to an online measurement of two-dimensional attitudes of the target plane utilizing the fact that the output signals from PSDs were reflection of the motion of the target plane.