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

本研究首先研制了一种特殊的极轻载荷触控笔仪器，用于测量圆盘表面周向轨迹的包络曲线。指出其测量精度（±1nm/15mm）较高，表面波长波段较市场上传统光学干涉仪宽。为了获得合适的高信噪比振幅数据，提出了一种精细的几何回归技术。考虑磁头滑块尺寸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），并采用常规滤波方法将原始包络曲线划分为多个波长波段。所研制的仪器所处理的轮廓与市售光学干涉仪OptiFlat非常吻合。在此阶段，引入了平均波长、算术平均振幅和Motif参数等地统计参数来评价圆盘表面的微波性。另外，对磁头读出信号进行测量和分析，了解磁头运行时表面轮廓与磁头飞行高度的关系。微波分量与磁头/磁碟界面处的电磁转换特性密切相关。结果表明，磁碟微波度对磁碟物理分离或硬盘的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.