Functional evaluation of surface waviness of contact recording magnetic disk and analytical estimation of head flying locus

首先，在本研究中，我们开发了一种超轻负载的光学针式测量仪器，用于测量沿磁盘表面周向轨迹的包络曲线。指出比市场上传统的光学干涉仪具有更高的测量精度(±1 nm/15 mm)和更宽的表面波长范围。为了获得高S/N比的合适幅度数据，提出了一种精细的几何回归技术，考虑了磁头滑块的大小及其对磁盘表面的跟踪运动，建立了评估磁盘表面微波度的测量条件(采样间隔、评估长度)，并采用传统的滤波方法将原始包络曲线划分为多个波长段。用所研制的仪器处理后的轮廓与商用光学干涉仪OptiFlat得到了很好的一致性。在该阶段，引入了平均波长、算术平均幅度和Motif参数等地统计参数来评估磁盘表面的微波度，并对磁头读出信号进行了测量和分析，以了解运行中磁盘表面轮廓与磁头漂浮高度的关系。微波波度分量与磁头/盘界面处的电磁转换特性密切相关。由此可见，磁盘的微波波度对硬盘的物理磁头-磁盘分离或信息存储密度有很大的影响。

First of all in this study, a distinguished stylus instrument with extremely light load was developed to measure envelope curves along the circumferential tracks of disk surface. Pointed out were the higher measurement accuracy (±1nm/15mm) and the wider surface wavelength band than conventional optical interferometers on the market. An elaborate geometrical regression technique was developed to obtain the proper amplitude data with high S/N ratio.Considering the head slider size and its follow-up motion to disk surface, the measuring conditions (sampling interval, evaluation length) for assessing the micro-waviness of disk surface were established and a conventional filtering method was adopted to divide the original envelope curve into several wavelength bands. A fairy good agreement was obtained between the processed profiles with the developed instrument and the commercial optical interferometer, OptiFlat. In this stage, some geo-statistical parameters such as mean wavelength, arithmetic mean amplitude and Motif parameters were introduced to evaluate the micro-waviness of disk surfaces.Additionally, the head readout signal was measured and analyzed to know the relationship between the disk surface profile and the head flying height in operation. The micro-waviness component was closely related to the electro-magnetic conversion characteristics at the head/disk interface. It can be concluded that the disk micro-waviness has a great influence on the physical head-disk separation or the information storage density of HDD.