数字三色条纹相移形貌投影栅线法

基于投影栅线的三色条纹相移算法与投影栅线法相结合,提出一种数字三色条纹相移形貌投影栅线法.此法是对时间相移法的改进,只需一幅三色条纹图,就可利用简单的三光强相移算法完成物体表面的形貌重建;不需要相移装置而误差较小,成本较低,简易实用,将有利于推广到动态实时分析.实验证明,此法是正确可行的.     

用白光信息处理作褪色透明片的彩色复原

本文提供了用白光信息处理技术作褪色透明彩色照片彩色复原的原理和实验,其中之一是由空间编码和彩色滤波两步骤完成的,即将待处理的透明彩色片用空间编码技术编制在一张黑白感光底片上,在白光光学处理系统的傅里叶平面中对这编码的黑白片的频谱进行彩色滤波,最后在系统的输出平面给出彩色增强或复原的图象,另一种是用白光处理技术作褪色透明彩色片的彩色复原实时处理,它可供及时的直接观察并且有操作简便,成本经济和能灵活多用的特点,这两种技术为彩色图象的彩色增强和复原提供了新方法。 关键词：     

Color signal correlation detection by matched spatial filtering

A polychromatic correlation detection technique by complex spatial filtering is presented. This technique utilizes a diffraction grating and three co-lineared (red, green, and blue) coherent sources. The technique of complex spatial filter synthesis for the polychromatic corelation detection is demonstrated. This technique offers true color correlation detection which is very suitable for color signal recognition and identification. The correlation diffraction efficiency with this technique is generally higher than that of the wavelength-multiplexed technique. Several interesting experimental demonstrations of this color signal correlation detection scheme are provided. Finally we note that this color signal detection technique is a simple and versatile processing technique which has broad range of applications of complex color signal detection, recognition and identification.     

光谱成像信息的数据融合技术在储层表征中的应用

光谱成像技术在矿物学和岩石学方面已得到广泛应用,然而,面对数量巨大、覆盖范围广阔的目标成像光谱数据,如何从中获取所需要的信息,并对其进行信息增强是需要亟待解决的问题。将显微红外光谱成像分析系统得到的实验结果,利用显微光谱成像信息的数据融合技术进行了数据处理,得到岩心样品中不同化学组分、基团的空间分布图。结果表明,利用该技术更好地揭示了不同烃类在岩石中的分布情况、孔隙的连通性等信息,显微光谱成像信息的数据融合技术为储层表征提供了一种新方法。     

Hybrid two-dimensional continuous wavelet transform for analysis of phase-shifted interferograms

In interferogram or fringe pattern analysis, a technique capable of automatically analyzing interferograms that contain complex fringes and high-level noise as well as defects is highly demanded. In this paper, a hybrid technique combining the concepts of the two-dimensional continuous wavelet transform technique and the phase-shifting technique is proposed. The novel technique takes the advantages of the two existing techniques, and has the ability to accurately and automatically analyze multiple phase-shifted complex interferograms involving noise and defects. The validity of the technique is demonstrated by both computer simulation and real experiment.     

相干场成像原理局限性分析

研究了相干场成像技术(又称傅里叶望远术)的基本原理,从理论上分析其局限性,明确定义测量对象并通过曲面积分推导成像过程中的数学关系.结果表明,该技术的重建图像中含测量对象表面的梯度信息,其对物体表面反射率分布的测量是不准确的,并进行了计算机仿真验证.这为评估该技术成像结果和进一步发展相干场三维成像提供借鉴.     

水下物体激光圆偏振成象实验及与线偏振成象的比较

采用波长532nm激光作光源,面阵CCD作探测器,利用圆偏振技术进行水下物体成象实验研究,对实验结果进行了分析并与线偏振成象技术进行了比较。结果表明无论是采用圆偏振技术还是线偏振技术都可提高水下物体成象的衬比（度）和成象距离;水体较清时圆偏振成象清晰度远远大于线偏振成象清晰度;当水体较混时,圆偏振成象清晰度大大下降和线偏振成象效果相接近。     

A Study on Usefulness Comparison of Multiple-Shot FSE PROPELLER and IDEAL-FSE Techniques for Magnetic Susceptibility Artifact

The aim of this study was to visualize multiple-shot fast spin echo (FSE) images using a periodically rotated overlapping parallel line with enhanced reconstruction (PROPELLER) technique. An iterative decomposition of water and fat with echo asymmetry and a least squares estimation (IDEAL) technique were also performed to reduce the image distortion or susceptibility artifact depending on the difference in magnetic susceptibility to the surrounding tissues caused by metal insertion. The utility of this technique was examined quantitatively. A ferromagnetic image was generated from all the metals, but the IDEAL technique caused less image distortion than the PROPELLER technique. The 3-point IDEAL technique, which used the difference in the signal phase of fat and water, required more time for the examination and image reconstruction than the PROPELLER technique, which was based on a rotating blade in k-space. On the other hand, the IDEAL technique was more useful for reducing the susceptibility artifacts. The use of a proper technique in clinical trials based on these results is expected to provide better clinical information for imaging diagnoses.     

偏振相位偏移电子散斑干涉术及其应用于变形测量

本文叙述了一种用于测量漫射表面变形的使用偏振相位偏移技术的电子散斑干涉术.由于采用共光路光学相位偏移技术,因而具有较高的稳定性;用计算机图像处理可精确地获得相位图;用去包裹技术(unwrapping)可直接得到表面变形的精确数据.     

Two-dimensional field mapping of monolithic microwave integrated circuits using electrooptic sampling techniques

Since the invention of the electrooptic sampling technique about ten years ago, this contactless test technique based on ultra-short optical pulses has become more and more attractive to microwave engineers developing monolithic microwave integrated circuits (MMICs). The electrooptic sampling technique was originally used for circuit internal measurements of very high-speed waveforms only at discrete test points. During the last five years, a new test technique, the two-dimensional electrooptic field mapping technique, has been developed and widely used. This test technique which measures the magnitude and phase of the microwave signal gives information not only of one discrete test point but also of a greater area within the circuit and therefore insight into the microwave field distribution. This two-dimensional electrooptic field mapping technique could be a powerful tool for studying fundamental properties of wave propagation in monolithic integrated microwave devices and circuits. The aim of this paper is to present the state-of-art of this new test technique and to show an example of its application.     

Attack on double-random-phase-encoding-based image hiding method

The double-random phase-encoding (DRPE) technique is a typical optical image encryption technique, which can also be used for image hiding. Usually, the secret image is encrypted with the DRPE technique and the encoded image is hidden into the host image via superimposition to obtain the stego-image. The attack technique on the DRPE-based image hiding method was proposed in this paper. Firstly, a randomly selected superimposition coefficient was used to approximate the original superimposition coefficient to extract the hidden encoded images from the stego-images approximately. Then, the chosen-plaintext attack technique on the DRPE-based optical image encryption technique was applied to recover the random phase masks used in the DRPE technique. The theoretical analysis indicated that, without considering the computational error, the recovered secret image via the proposed attack technique is identical to the original one. Even considering the computational error, it is identical to the secret image recovered with the original DRPE-based image hiding method, which demonstrates that the attack on the DRPE-based image hiding method is successfully achieved. The numerical simulation results demonstrated the correctness of the theoretical analysis.     

Usefulness of the navigator-echo triggering technique for free-breathing three-dimensional magnetic resonance cholangiopancreatography

Purpose

To prospectively compare the navigator-echo triggering technique (navigator technique) and the conventional respiratory triggering technique using bellows (bellows technique) for free-breathing three-dimensional (3D) magnetic resonance cholangiopancreatography (MRCP) under clinical conditions.

Materials and methods

Forty patients referred for evaluation of biliary or pancreatic diseases underwent 3D MRCP examination using both navigator and bellows techniques. Two independent radiologists visually evaluated the image quality of 12 segments of the pancreaticobiliary tree in a blinded manner. In addition, the clarity of the lesion was compared between the two techniques in a side-by-side manner.

Result

MRCP images were successfully acquired using both techniques in all patients. No significant difference in acquisition time was found between the two techniques. The image quality was significantly better using the navigator technique than using the bellows technique for the following seven segments: the head, body, and tail of the pancreatic duct; right hepatic duct; anterior and posterior segments of the right hepatic duct; and cystic duct. The other segments (common hepatic and bile duct, left hepatic duct, medial and lateral segments of left hepatic duct, gallbladder) showed no significant difference. The clarity of lesion depiction was significantly better using the navigator technique than using the bellows technique.

Conclusion

Respiratory-triggered 3D MRCP using the navigator technique was shown to be feasible in routine clinical practice. The navigator technique improved the image quality of free-breathing 3D MRCP compared with the bellows technique. The clarity of lesion visualization was also better using the navigator technique than using the bellows technique.     

Multislip spatial filtered pseudocolor holographic imaging

A technique of pseudocolor encoding of spatial holographic imaging by a multslit rainbow process is illustrated. The encoding takes place at the spatial frequency plane of a coherent optical processor. The pseudocolor hologram imaging is obtained by white light reconstruction of the multiplexed rainbow hologram. The basic advantage of this technique as compared with the multiwavelength technique is the elimination of multicoherent sources. This multislit technique provides a simple encoding process for which a broad range of pseudo-color holographic images can be easily obtained. The potential applications of this technique may range from aerial photography for remote sensing to X-ray transparencies for medical diagnosis.     

表面热透镜技术测试光学薄膜特性研究

在薄膜特性的研究工作中，激光引起的表面形变是一种广泛应用的技术。在这种技术中，薄膜的形变(热包高度小于0．1nm)一般是采用光热偏转技术来探测的。介绍了一种通过光学衍射效应来研究薄膜表面形变的新技术即表面热透镜技术，它是研究薄膜特性的一种灵敏且易于控制的方法。探讨了其理论模型及在薄膜的吸收测量和缺陷特性测试方面，该方法相对于传统方法的优点和潜力。     

Two Methods for Extending Quantum Key Warehouse

Because the rates of quantum key distribution systems are too low, the interleaving technique and interpolation technique are used to extend the capacity of the quantum key warehouse to increase the quantum key rates of quantum secure communication systems. The simulation shows that the interleaving technique and interpolation technique can extend random sequences and that their randomness are invariable. The correlative theory and technique of digital signal processing is an effective method of extending the quantum key warehouse. Translated from Chinese Journal of Quantum Electronics, 2005, 22(1) (in Chinese)     

Spectral characterization of fiber gratings with high resolution

We demonstrate a high-resolution technique to measure the optical magnitude and phase responses of fiber gratings. The technique employs single-sideband modulation of an optical source and has spectral resolution in the hertz regime. The technique is demonstrated by measurement of the phase ripples of unapodized and apodized chirped gratings as well as the transmission spectrum of a pi-phase-shifted grating. Although it is demonstrated on fiber gratings, the technique is applicable to any optical device.     

彩色图象的光学信息处理

本文研究了在相干多色处理中用黑白透射介质进行彩色图象空间编码的方法。这个方法可应用于彩色象的信号检测、去模糊、及相加与相减。并且指出,类似于相干单色处理,这种多色处理方法有能力处理彩色图象。这个方法虽然有某些不足之处,例如需要对被处理对象事先进行编码。但是,这个方法展示了在彩色图象处理中的一个新的方向。而且,它并不只局限于处理彩色图象,也可应用于处理某些具有灰度变化的图象。 关键词：     

Scale invariant amplitude modulated phase-only filtering

A new synthetic discriminant-function-based amplitude modulated phase-only filtering technique is proposed for scale invariant pattern recognition. This technique has been found to yield improved correlation output when compared with the alternate techniques. The proposed technique is inherently suitable for optical implementation using the currently available spatial light modulators. Simulation results confirm the effectiveness of the proposed technique.     

基于QKD系统的扩展量子密钥方法研究

研究用交织技术和插值技术来扩展已有量子密钥库的容量,以期提高量子保密通信系统的量子密钥生成速率.初步仿真结果显示:采用交织技术和插值技术能扩展随机序列,且其随机性能不变.     

Two-dimensional quantitative imaging of multicomponent samples using polychromatic X-rays

We present the theoretical formalism and an experimental demonstration of a technique for two-dimensional quantitative imaging of two-component samples using polychromatic X-rays. The technique takes into account the full spectral information of the incident polychromatic beam to quantify the total X-ray attenuation, due to each component presented in the sample, as functions of both energy and thickness. As a result, this technique is able to effectively ameliorate the effects of beam hardening. Here, we demonstrate the application of this technique to a two-component sample. The technique makes it possible for laboratory-based polychromatic X-ray sources to be used for critical quantitative purposes.