模糊控制与图像处理技术实现的聚焦方法

为提高图像测量系统的精度,提出了一种由模糊控制与图像处理技术实现的自动聚焦方法。通过线性拟合与同态滤波滤除噪声后,用改进的梯度平方函数作为聚焦评价函数,提高了聚焦灵敏度;运用模糊控制技术改换搜索方式,实现了实时自适应变步长搜索,保证系统快速准确聚焦。实验结果表明,该聚焦方法具有单峰性,响应快,鲁棒性强,在±100μm范围内自动搜索,定位时间小于2″,聚焦不确定度达±1μm。     

光电工程2001年(第28卷)总目录

第1期（总第152期） 相移掩模和光学邻近效应校正光刻技术………………………………………… 冯伯儒，张 锦，侯德胜，周崇喜，苏 平(1) 纯角度跟踪的球面坐标降维算法…………………………………………………………………… 胡磊力，陈钰清，邹盛怀(6) 电子束反应蒸发氧化物薄膜的应力特性…………………………………………………………… 熊胜明，张云洞，唐晋发(13) 准线性区光盘聚焦自动预搜索机制的研究………………………………………………………… 蔡忠平，徐端颐，潘龙法(16) 一种数字测图中的自动曝光控制技术………………………     

基于无热化检测系统的自动聚焦算法的研究和实现

本文介绍了一套基于该系统的自动聚焦方案，方案中分别用SMD算法和拉普拉斯算法作为粗细两次调焦的自动聚焦评价算法，并用斐波那契搜索方法和爬山法作为粗细两次调焦的搜索方法。而且本文利用Visual C＋＋把所有功能集成到一起，实现了对无热化检测系统的自动聚焦功能。经过大量实验表明，本文提出方法有良好的实时性和准确性，并且具有较高的精度和重复性。     

第三讲有关光盘技术术语解释

第三讲有关光盘技术术语解释陈玉生编著下面阐述有关光盘术语的解释，这会有助于你对光盘有更好的理解。１、随机存取随机存取是自动搜索到所规定位置和从那个位置到另一个所规定位置的重放，或在所规定方式下根据所规定时间从一个所规定位置的重放操作。在视盘放机情况，...     

遗传算法在分数阶Fourier变换域极值优化中的应用

分数阶Fourier变换采用线性调频基,因此,线性调频（Linear Frequency Modulation,LFM）信号在分数阶Fourier域平面能够聚焦,并形成峰值。为了克服传统步进式搜索法在LFM信号峰值搜索中效率低下的缺点,将遗传算法引入到分数阶Fourier变换极值搜索中。仿真结果表明,该方法优于传统的步进式搜索法。     

光盘的ZCAV方式及其预格式信息检测

介绍了在光盘驱动器中，ＺＣＡＶ，ＣＡＶ和ＣＬＶ的工作方式和特点，检测了符合ＩＳＯ标准的磁光盘预格式信息和非标准的ＺＣＡＶ方式工作的相变光盘预格式信息。     

130mm磁光盘预格式信息的测试与分析

本文对130mm磁光盘的导向槽和预格式区的记录信息位进行测试,并对其结果作了分析和讨论。     

免疫算法在分数阶Fourier变换域极值优化中的应用

利用线性调频(Linear Frequency Modulation,LFM)信号在分数阶Fourier域上的聚焦性,通过搜索可实现LFM信号的检测和参数估计。通常采用步进式搜索法,效率低下。为了克服该缺点,通过对分数阶Fourier域优化问题的研究,将免疫算法引入到分数阶Fourier变换极值搜索中。仿真结果表明:该方法优于传统的步进式搜索法。     

大屏幕彩色显像管电子枪电子束形成区及预聚焦透镜特点分析

束形成区及预聚焦透镜是大屏幕彩色显像管电子枪的设计重点之一。本通过计算机模拟的方法对几种大屏幕彩色显像管用电子枪束形成区及预聚焦透镜的特点进行了系统分析，比较了各电子枪在不同电流下最小交叉截面位置的波动、最大电流密度的变化、主透镜中束截面形貌。分析表明束形成区和预聚焦透镜均采用四极结构的电子枪更容易实现聚焦稳定性和附加理想的像散。     

光盘光学头抗振性研究

分析了光盘盘片轴向抖动及光盘基座振动对光学聚焦伺服的误差的影响，建立了它们的数学模型，获得了频率响应特性，设计了一种在５￣２０００Ｈｚ范围无谐振峰的微型隔振系统。     

面向对象的光学系统自动对焦方法

基于光学系统的焦深及其与工件的相对位置关系等硬件因素,提出光学系统面向对象的快速对焦运动控制方法。该方法采用灰度差分法来构造聚焦特征值评价函数,并使成像系统的运动轨迹尽量短。将对焦过程分为纯线性运动、粗调焦和细调焦三个阶段,每个阶段控制参数的确定方法不同,但总的原则是尽量减少运动和缩短图像处理中的运动距离,尽量增大最小运动步长,利用变步长的浮动阈值搜索方式,克服局部聚焦和完全不能聚焦的情况。实例证明,该方法可以提高对焦效率和可靠性,35mm的对焦距离大约耗时10s左右。     

Acousto-optic tunable filter chromatic aberration analysis and reduction with auto-focus system

An acousto-optic tunable filter (AOTF) displays optical band broadening and sidelobes as a result of the coupling between the acoustic wave and optical waves of different wavelengths. These features were analysed by wave-vector phase matching between the optical and acoustic waves. A crossed-line test board was imaged by an AOTF multi-spectral imaging system, showing image blurring in the direction of diffraction and image sharpness in the orthogonal direction produced by the greater bandwidth and sidelobes in the former direction. Applying the secondary-imaging principle and considering the wavelength-dependent refractive index, focal length varies over the broad wavelength range. An automatic focusing method is therefore proposed for use in AOTF multi-spectral imaging systems. A new method for image-sharpness evaluation, based on improved Structure Similarity Index Measurement (SSIM), is also proposed, based on the characteristics of the AOTF imaging system. Compared with the traditional gradient operator, as same as it, the new evaluation function realized the evaluation between different image quality, thus could achieve the automatic focusing for different multispectral images.     

Versatile polychromatic dynamic testbed for optical disks

A dynamic testbed for the evaluation of optical disks has been designed and constructed. The system is achromatic within the wavelength range 440-690 nm, allowing any light source in this range to be utilized for read-write-erase experiments. In addition, the system accepts disks with substrate thicknesses ranging from 0 to 1.7 mm. The polarization handling capabilities of the testbed are such that, with the turn of a knob, one can generate either linearly polarized or circularly polarized light at the disk surface. This feature permits the testing of both magneto-optical and phase-change disks, in addition to compact disks and digital versatile disks, without any modifications to the system. A leaky polarizing beam splitter (LPBS) has been specially designed and built for this tester. The LPBS allows continuous adjustment of the ratio between p- and s-polarized components of the reflected beam that reach the detectors. This feature is especially useful for magneto-optical disks, where one can achieve an optimum signal-to-noise ratio by adjusting the relative amounts of the two components of polarization at the detection module. Focus-error detection is based on the astigmatic method, and the primary track-error detection scheme is the push-pull method, although other focusing and tracking schemes may also be implemented. The rf data signal and the focusing and tracking servo signals are all derived from the same detectors, thus allowing the optical power returning from the disk to be used in its entirety for these multiple purposes. The detection channel consists of two high-speed quad detectors mounted on the two arms of a differential detection module. By combining the various outputs of these detectors it is possible to generate the astigmatic focus-error signal, the push-pull track-error signal, the differential magneto-optical readout signal, the conventional sum signal for phase-change disk readout, and the differential edge-signal for mark-edge detection on various types of optical media.     

用于LDA系统校准的独特旋转盘

分析了激光多普勒测速系统校准的必要性，提出了用单一粒子已知的确定速度标准的新思路。据此专门设计了一种独特的用于ＬＤＡ系统校准的旋转盘。通过试验验证了校准盘系统的转速稳定性并证明了线速精度伯均达到或优于设计参数的要求；所以，校准盘的线速度可作为参考速度与ＬＤＡ系统或其它光学风速计的测量速度进行比较，并对上述仪器进行评估。     

Multispeed rewritable optical-recording method with an initialization-free phase-change disk

A new method of multispeed rewritable optical recording is presented. An initialization-free phase-change optical disk is proposed as a candidate for multispeed rewritable optical recording. The simulated results of the initialization-free disk at different linear velocities show that the cooling rate increases from approximately 18.69% to 37.96%. A model that combines the crystallization acceleration effect due to the additional layers and the rapid cooling rate due to the initialization-free disk structure is proposed as the physical mechanism of the multispeed recording method with an initialization-free disk. The dynamic optical-recording properties of the initialization-free DVD-RAM disk at different recording speeds shows that the initialization-free phase-change optical-recording disk is compatible with a broad range of recording speeds from 3.49 to 12.21 m/s.     

航拍高光谱图像中基于投影的自动目标检测算法

针对未知环境条件下的高光谱图像目标检测问题进行了研究,提出了一种基于投影的自动目标检测算法。该算法通过构造正交投影算子预先对部分干扰物信息进行削弱,再以无监督的自动目标搜寻方法找到场景中可能的目标物,将图像数据向可能目标物所张成的子空间投影以增强目标物的信息,然后用匹配的方法完成检测。有效减弱了干扰物对目标检测的影响,缩小了目标搜索的范围。应用此算法对实验采集数据进行处理,取得了较好的结果。     

基于灰度差分法的自动调焦技术

如何快速有效地实现调焦一直是图像测量中的焦点;基于光学镜头和CCD图像采集技术提出了一种图像式自动调焦系统,并给出了以图像的灰度差分绝对值之和作为图像是否聚焦的判据函数,以及给出了逐步逼近的登山式自动调焦的原理,对该系统进行了实验研究,系统重复精度为8000nm。     

Subtle effects of the substrate in optical disk data storage systems

Much attention has been focused on the effects of the disk substrate in optical data storage. In particular, substrate birefringence has been studied extensively because it causes significant problems in magneto-optic systems. We investigate certain subtle effects of the substrate, such as feedback into the laser diode, in compact disk and phase-change systems. Our analysis of the compact disk system led us to discover a new technique for the rapid measurement of the substrate birefringence. We also address the question of how focusing the laser beam through the substrate will affect the depth of focus.     

Effect of surface plasmon excitations on the irradiance pattern of the return beam in optical disk data storage

The excitation of surface plasmons at a dielectric-metal interface is responsible for dips in the zeroth order diffraction efficiency of a metal grating at certain angles of incidence. The dips appear as dark bands in the returning irradiance pattern in an optical disk system and are seen only when there is a component of incident polarization that lies perpendicular to the tracks. The location of these bands is derived from theoretical considerations and is shown to depend on the track pitch and the materials involved, but not on the groove depth or width. The band locations are confirmed by zeroth order diffraction efficiency measurements as a function of incident angle. A possible negative effect of these bands on an optical disk system is the introduction of additional fluctuations and noise into the focusing and push-pull tracking signals.     

磁光盘驱动器聚焦与循轨数字伺服系统

分析了磁光盘驱动器聚焦与循轨数字伺服系统各组成部分的原理，并设计和实现了一套基于ＤＳＰ的数字伺服控制系统，仿真和实验结果表明：这种数字伺服系统的设计方案简化了电路设计，系统性能良好，是一种理想的系统实现方式。