纳米级微间距的多波长干涉测量方法

多波长干涉测量法适用于纳米级微间距的实时动态非接触测量.纳米级间隙之间的空气形成一层具有光学特性的空气薄膜.该空气薄膜的光强反射率是关于入射光波长和薄膜厚度的函数.在多波长干涉法中,以包含多种波长的复合入射光照射薄膜,入射光被空气薄膜分成2部分,一部分穿过薄膜,另一部分则被反射回来.利用一种特殊的方法测得该薄膜的光强反射率,进而根据薄膜厚度与入射光波长和相应的光强反射率之间的函数关系建立方程组.通过对方程组求解,计算出薄膜的厚度.多波长干涉测量法能够避免移相干涉法中移相器所带来的误差,并且可根据不同波长的光波测出的结果相互校正,提高了测量精度.通过实验对多波长干涉测量法进行了验证,实验结果充分证明了系统设计及理论依据的正确性.     

Consideration and compensation for precision optical flying height measurement

It is a big challenge to determine ultra-low slider flying height accurately. The intensity interferometry flying height testing method is widely used to determine slider flying height. However, the intrinsic measurement errors of the method are becoming non-negligible with the decrease in slider flying height. Strategies have to be developed to minimize the errors. To measure flying height with a normal incidence optical flying height tester, a calibration process is required to determine several constants used in flying height calculation. In practice, the calibration is usually done simply by retracting the slider from the disk and measuring the intensity minima and maxima of the interferogram during the retracting process. It has been demonstrated that the single most important source of error in the flying height measurement is associated with errors in the determination of the intensity maxima and minima. In this work, the effects of optical filter, the responding frequency of photodetector, and the lack of the first order intensity minimum on the determination of the intensity maxima and minima are studied. Methodologies to minimize the errors in flying height measurement caused by the above factors are developed.     

磁盘速度与容纳系数对硬盘气膜静态特性的影响

随着硬盘(Hard disk drives,HDDs)中浮动块与磁盘间飞行高度的降低,气体分子与磁头/磁盘间的交互作用逐渐增强,磁盘速度及容纳系数(Accommodation coefficients, ACs)对气膜承载特性的影响越来越重要。采用一种无网格法—最小二乘有限差分(Least square finite difference, LSFD)法,对简化的分子气膜润滑(Molecular gas film lubrication, MGL)方程进行求解,研究了磁盘速度、磁头和磁盘表面ACs对HDDs超低飞高气膜静态特性的影响。数值结果表明：对称性分子交互作用时,磁头和磁盘表面ACs对气膜静态特性的影响明显;非对称性分子交互作用时,磁盘表面ACs对气膜静态特性的影响较大,而磁头/浮动块表面ACs的影响较小;不同ACs条件下,随着磁盘速度或最小飞行高度的增加,压力幅值点位置的变化较均匀。     

Noncontact surface roughness measurement of engineering surfaces by total integrated infrared scattering

As precision engineering surfaces are gaining in importance in industry, so are the surface quality requirements. These surfaces have rms roughness typically ranging from some nanometers up to a few micrometers. Although numerous techniques exist for rough surface characterization, from traditional line-scanning stylus profilometers to modern three-dimensional (3-D) measurement instruments, there is a need for a fast, area-covering technique. An efficient method for the characterization of smooth surfaces is elastic light scattering. At visible wavelengths, the limits on roughness range and spatial frequency range make the method unsuitable for characterizing engineering surfaces. By increasing the wavelength of the incident light from the visible to the infrared, elastic light scattering turns out to be applicable for engineering surfaces. We have used total integrated scattering at 10.6 μm wavelength to measure rms roughness up to two micrometers. In this paper, the instrument design and properties are reviewed. We also present results from measurements on ground steel surfaces. Excellent correspondence with mechanical stylus measurements exists for surfaces with rms roughness in the range from 0.1–1.7 μm. The technique shows potential for rapid quality inspection of engineering surfaces.     

宽视场绝对辐射计杂散光特性研究

摘要：卫星太阳辐射监测仪在轨飞行中采用太阳扫过宽视场绝对辐射计视场期间动态测量太阳辐照度的方法,测量过程中进入辐射计接收腔的杂散光对测量精度带来影响,本文通过模型软件分析、风云辐射计外场标定测量和神舟三号辐射计在轨数据修正三个方面对宽视场辐射计的杂散光随角度变化分布进行了分析, 1）随光线入射角增大,杂散光影响基本呈线性增大;2）太阳辐射监测仪宽视场绝对辐射计无遮拦视场角18.4,对0～7视场进行了模拟分析,在7入射角时,杂光影响为0.63％,地面通过标定方法测量得到的结果为0.79％;3）神舟三号飞船上的辐射计视场角为10.4,视场角小,消光光栏多,杂散光的影响相对较小。以模型仿真结果对星上获得数据进行了修正,结果表明,通过杂光修正降低了系统误差。     

基于CCD相机的光纤传像器件光谱透过率测试仪设计

光谱透过率是分析光纤传像器件透光性能的一个关键参数,提出了一种用积分球与CCD相机的光谱透过率测试仪的原理、组成和图像处理软件。方法是通过计算不同波长下图像的灰度值,测量光谱透过率。对仪器所需的光源、滤光片的特性进行了分析。测试结果表明,对于不同厚度的光纤传像器件,光谱透过率的变化规律基本一致。检测证明这种仪器测试速度快、操作方便,测量结果准确可靠。     

Drive level measurement of flying height modulation and control of slider disk contact

A drive level measurement of flying height modulation and a demonstration of slider-disk contact control was conducted. The results of the flying height modulation strongly agree with those obtained from a Laser Doppler Vibrometer (LDV) measurement. The modulation was mainly caused by curvature caused by disk clamping. Furthermore, feedback control of a slider-disk contact was successfully demonstrated. Friction force was controlled at a small value to maintain the slider so that it flew over the disk in the light contact regime.     

Critical Operating Conditions For A Novel Flying Tester

Increased recording densities are often achieved through a reduction in the flying height over a thin film disk possessing diminishing surface roughness. Flying heights will continue to decrease until the head-disk interface (HDI) operates under quasi-contact conditions, i.e., ultra-low flying with intermittent slider-disk collisions. The failure mechanisms that occur in such quasi-contact devices may differ from those experienced in current, higher flying hard drive assemblies. In this paper, the authors will present the experimental, numerical, and theoretical tools that have been developed to study the behavior of the HDI under ultra-low flying conditions. These tools include an accelerated flyability tester and a numerical algorithm applicable to highly rarefied air bearings that possess large pressure gradients. Air bearing simulation results, as well as the results from a simple flying height scaling analysis, will be compared to flying test results in both air and helium to obtain insight into the stability of the HDI under accelerated testing conditions. A new concept introduced in this paper is that of critical conditions, i.e., the band of operating conditions which mark the transition from stable to erratic behavior, which can be determined both experimentally and theoretically. Such insight should provide design criteria for both quasi-contact storage devices, as well as novel accelerated wear testers.     

多波长消光测粒技术的一种改进方法

:在详细研究现有多波长消光测粒技术的基础上 ,分析了各个波长下各透射光强之间的内在联系 ,并提出消光测粒技术在具体应用中的一种新的改进方法。     

Slider–bump contact and flying height calibration

It is a big challenge to determine ultra-low slider flying height accurately. The standard bump disk method is probably the most reliable and acceptable method so far. One of the key issues to determine slider-flying height with the bump disk method is the complicated slider–bump interaction process and the possible disturbance of the bumps on the slider flying performance. Our knowledge about the slider–bump interaction process is still very limited due to the lack of an effective and powerful experimental technique to study it. In this work, the slider–bump interaction process was studied with a dynamic flying height-attitude (3D) system. The interaction process was also simulated to compare with the experimental observations and to help determine the slider–bump contact points in the experimental observations. The accuracy of flying height (FH) calibration with the bump disk method and the minimum slider–bump interference height required for the testing system used in this study to detect the onset of slider–bump contact were analyzed and discussed. It is proved that the 3D system is a very useful and powerful tool for the application. Many details of the slider–bump interaction process can be revealed with the 3D system. It is found that the calibrated FH is much more accurate than that predicated by the simulations.     

可进行样品移动扫描的光电直读光谱仪

火花直读光谱仪是通过电弧火花放电,在样品表面蒸发出部分样品,样品中的不同元素通过电子跃迁发射出特征谱线,通过测量这些元素的特征谱线波长和谱线强度,就可以测量出样品的组成。本文所述的带有样品移动系统的光电直读光谱仪是一种新型仪器,它与脉冲分布分析技术相结合,在中心线偏析及硫化物夹杂两方面得到了很好的应用。     

Characterization of Local 3-D Rough Dielectric Surfaces Using Standoff GPR Measurements with Widebeam Antennas

In real life most ground surfaces are not flat but rough. The observation of surface roughness depends on the wavelength and angle of the incident wave. In order to be able to detect shallow subsurface objects, on one hand we need to use higher frequencies to achieve better range resolution. One the other hand we have to deal with rough surfaces relative to shorter wavelengths. In this paper a wideband ground-penetrating radar (GPR) phase measurement and processing technique for characterizing three-dimensional (3-D) rough dielectric surfaces is presented. The method is based on the measurement of phase data by a standoff GPR with wide-beam antennas at short range over 3-D rough ground surfaces. The principle of this method was verified experimentally in the measurement of a composite surface. The height of the composite surface varies from 0 to 8 cm. The antennas are open-ended waveguide antennas whose frequency range is 2.3 GHz to 4.3 GHz. They are broadband, have low gain and wide beamwidth. The experimental tests demonstrate that the 3-D rough surfaces can be characterized locally by using a monochromatic and multifrequency broadband phase processing and imaging method. The results show good agreement between the imagery of the surface height distribution obtained by this method and the actual geometry of the 3-D rough surfaces.     

一种简易光谱实验仪的设计与实现

针对传统光谱仪在实验教学方面存在的问题,设计了一种成本低、体积小的简易光谱实验仪。该光谱实验仪可以探测340¹ 000nm光谱范围内的光。基于光敏三极管良好的光电特性和光谱特性,用中心波长不同的窄带滤光片将入射光分光后分别照射到相应的光敏三极管上。定量反映光照度的各光敏三极管所产生的光电流,经电路转换成电压并放大后被计算机实时采集,利用相应VB程序的处理,在程序界面上实时呈现光谱图。通过探测卤钨灯的光谱,与传统光谱仪探测的光谱图相比较,观察得到两者光谱图包络基本一致,满足了教学实验仪的需求。     

Simulation of Static Flying Attitudes with Different Heat Transfer Models for a Flying-Height Control Slider with Thermal Protrusion

The thermal flying height control (TFC), aka dynamic fly height (DFH), technique has been recently used in the head disk interface of hard disk drives to obtain a lower head-media spacing. The air bearing cooling effect, i.e., the heat conduction between the slider and the air film, has been incorporated in the numerical thermal–mechanical simulation of the slider’s static performance. However, the heating effect of the viscous dissipation of the air flow has not been considered yet. In this article, both effects are included in the simulation of a flying slider with its flying height controlled by thermal protrusion, and different models for the air bearing cooling are used to obtain the slider’s static flying attitudes. The simulation results directly show that the air bearing cooling is dominant compared with the viscous heating. All of the air bearing cooling models, including a recent one that considers the dependence of the air molecular mean free path on the air temperature, have simulation results close to each other. The largest relative difference in the simulated flying height is less than 9% even when the transducer flying height is lowered to below 2 nm.     

Dominant Factors in Lubricant Transfer and Accumulation in Slider-Disk Interface

Lubricant transfer from disk to slider and lubricant accumulation on slider are very important in designing a stable slider-disk interface of ultra-low spacing. In this article, the effects of different parameters on the lubricant transfer and accumulation are studied and the reasons behind the effects are explained. Furthermore, the time for the lubricant transfer to reach steady state is estimated. It is found that lubricant molecular weight plays a dominant role in the lubricant transfer and accumulation. Lubricant transfer and accumulation decrease dramatically with the increase in lubricant molecular weight. Lubricant transfer also strongly depends on lubricant thickness and bonding ratio on disk surface. A thinner lubricant and higher lubricant bonding ratio on disk surface reduce lubricant transfer obviously, which results in less lubricant accumulation. A diamond-like-carbon (DLC) overcoat of low adsorption area density on slider surface can reduce lubricant transfer and accumulation, especially for lubricant of low molecular weight. Lubricant accumulation increases with disk velocity and increases slightly with the decrease in slider flying height. Lubricant accumulation can be reduced by minimizing the area of slider pad. Lubricant transfer and accumulation become worse at higher ambient temperature. It takes seconds for lubricant of low molecular weight to reach steady transferred thickness and hours for lubricant of high molecular weight to reach the steady state.     

Dynamic microwaviness measurements of super smooth disk media used in magnetic hard disk drives

Recent technological advances in magnetic storage suggest the feasibility of extremely high-density magnetic recording up to 1 terabit per square inch (1 Tbit=10¹² bits) areal densities. Modelling indicates that approximately 3 nanometers (nm) of physical head-disk spacing is required for such high recording densities. When the recording slider is flying at such ultra low spacing over a high-speed rotating disk, it is experiencing disturbances from various different sources and of a wide frequency range. These disturbances may cause the recording slider to vibrate significantly, a condition that is known as fly height modulation (FHM), which may result in data loss. A significant source of excitation is from the surface irregularities of the rotating disk and is termed dynamic microwaviness. The term dynamic microwaviness has been introduced recently to differentiate from regular topographical features that are measured statically. In this paper, the procedure for making reliable dynamic microwaviness measurements of disk media used in hard disk drive (HDD) systems is described. Furthermore, such measurements are performed on different super smooth magnetic disks that are intended for extremely high recording densities using non-contact laser vibrometry. The root-cause of the dynamic microwaviness is investigated by measuring disk topographical features under static conditions and the interaction with system dynamics. It is found that dynamic microwaviness is primarily due to topographical features of spatial wavelengths ranging from 58.8 to 250 μm, and secondarily due to system dynamic effects.     

考虑偏振片非理想性的可见光偏振成像修正模型

常用的偏振成像理论模型大多基于理想偏振片假设,即偏振片的消光比为无穷大且主方向已知,而实际偏振片的非理想性会对偏振成像系统的测量精度产生明显的影响,为降低这种影响,对考虑偏振片非理想性的偏振成像模型进行研究。以基于斯托克斯矢量的偏振成像模型为基础,通过分析实际偏振片对入射光偏振态的改变,提出了一种考虑偏振片非理想性的可见光偏振成像修正模型,给出了考虑实际偏振片性能及主方向误差的偏振度、偏振角修正公式。利用分时偏振成像系统对线偏振光的偏振度进行测量,实验结果表明:当偏振片消光比为100:1时,理想模型的线偏振光偏振度测量的平均相对误差为5.53%,修正模型的偏振度测量的平均相对误差降低到3.62%。应用该修正模型可在使用低消光比偏振片时达到与高消光比偏振片相当的偏振度测量精度,使偏振成像系统能够拥有更大视场,成本降低。     

关节轴承球面尺寸检测仪的误差修正方法

针对关节轴承球面尺寸检测仪专用于测量不同尺寸系列工件的特点,提出了关节轴承球面尺寸检测仪误差在线辨识与修正法。该方法通过在线测量系列工件和分析实测结果,可以准确地辨识并修正仪器系统误差,具有无须借助标准件、可低成本大幅度提高测量精度的优点。实验结果表明,使用该方法,仪器的测量值与高精度仪器测量值的偏差在10μm以内,最大测量误差由修正前的0.110mm减小到0.004mm,仪器测量精度明显提高,满足了企业提出的测量精度要求。     

航空多角度偏振辐射计的偏振定标

研究了航空多角度偏振辐射计的辐射定标方法,以消除其自身引入的偏振效应,提高偏振辐射计的测量精度.首先,根据引入仪器偏振效应的主要因素推导了含定标系数的仪器探测方程,由仪器在0°和90°两个状态下对同一信号的探测方程求解了定标系数表达式,并设计了仪器分别处于两个状态下获取信号、求解定标系数的定标方法.最后,分别针对非偏振光源和完全线偏振光源的测试数据求解了所有的定标系数,使用可调偏振度光源验证了偏振定标结果.结果显示,该仪器偏振测量精度不低于o.5％,满足仪器精度指标要求.     

Ultra-low-flying-height design from the viewpoint of contact vibration

The design of a head-disk interface for ultra-low flying height has been studied from the viewpoint of contact vibration. It is known that a super-smooth disk is necessary for a slider to fly at an ultra-low flying height; however, such a disk increases the friction force, which potentially increases the vibration of the slider. To solve this problem, the head-disk interface must be optimized to reduce this increased vibration. It has been shown that a large pitch angle and center-pad-mounted read/write elements have advantages in terms of slider/disk contact. It has also been found that a micro-texture on the air bearing surface can prevent contact vibration. Moreover, a frequency-shift-damping slider was found to damp the vibration effectively. To further investigate these findings, numerical simulation and modeling of slider dynamics during contact have been performed. Their results revealed two zones of contact vibration: a stable zone and an unstable zone.