二次全息法复制全息光栅柱面镜

本文叙述了用二次全息复制全息光栅柱面镜的方法。     

强激光束在柱面镜空间滤波器中的传输特性

为了解决空间滤波器滤波针孔堵孔问题,提出了一种新型柱面镜空间滤波器,新型柱面镜空间滤波器由柱面镜和狭缝构成。利用线性传输理论,对高功率激光束在新型柱面镜空间滤波器中的传输特性进行了数值模拟。结果表明:新型柱面镜空间滤波器的焦斑面积比传统滤波器大,而焦斑功率密度较小;新型柱面镜空间滤波器的滤波效果与传统滤波器相同,近场均匀性也相同。因此新型柱面镜空间滤波器能够抑制空间滤波器堵孔效应,可以缩短空间滤波器系统透镜焦距,从而提高功率装置的整体性价比。由此,采用新型柱面镜空间滤波器替换传统球面镜空间滤波器具有可行性。     

光束整形系统异形元件的研制

为了实现非球柱面镜的高精度加工,解决这一领域面临的难题,对非球柱面镜的加工和检测方法进行了深入的研究。采用古典与现代制造技术相结合的方法,研制了用于光束整形的异形元件,该异形元件是由非球柱面镜和柱面镜组成。针对非球柱面镜面型难以控制的问题,给出了独特的抛光模设计。结果表明：经过轮廓仪检测面型精度为0.848 7 μm,达到了图纸精度,满足了光学元件的使用要求。     

小半径柱面镜光学加工工艺研究

针对某新型导弹激光系统提出的小半径柱面镜,通过对传统柱面镜加工方法的综合分析比较,选择合适的加工方法、用不同抛光模层进行抛光比较,对多种分离器材料和分离器槽的长短、模具的摆动幅度等进行工艺试验,使小圆棒柱面镜的表面粗糙度最小值达到Ra 0.005 m,优于设计图纸表面粗糙度Ra 0.01 m的要求,后续再磨去多余的半个圆柱,形成并达到平面的技术要求,满足了此半圆柱状的小半径柱面镜全部技术条件,形成稳定批产加工能力。     

关于柱面镜成像的讨论

柱面镜以及一般镜面的成像规律问题,涉及到高阶方程的求解,在现行光学教材中缺少具体的答案.本文提出了柱面镜成像的物像方程式,并用计算机绘制了物像关系图.     

牛顿等厚干涉平行直纹实验的设计及研究

根据薄膜干涉原理设计了等厚干涉平行直纹实验装置,以等厚干涉为基础,通过读数显微镜装置,拓展了等厚干涉在实验教学中的应用。通过测量左右对称分布且明暗相间的平行直纹到中央零级直纹的距离,可以得到平凸柱面镜的曲率半径以及液体折射率。在平凸柱面镜上平面覆盖一层待测液体,可以增大入射光进入透镜的透射率,增强透射光的光强度,提高干涉条纹的亮暗强度。等厚直纹干涉现象清晰直观,实验操作简单方便,加入待测液体,无须拆开干涉装置,可以保证在相同的空气薄膜厚度下进行测量,降低实验的误差。同时该设计研究可以促进学生的动手实践与创新能力的提高,为探究式实验教学提供很好的案例和实践。     

交叉柱面镜腔的研究

使用矩阵理论,对两个交叉成任意角度的柱面镜构成的谐振腔作了深入的理论研究.分析了这类光腔的稳定性、模式分布和腔内光束传输特性,并以数值计算例说明.对我们使用交叉柱面镜腔的钕玻璃板条激光器有关的实验结果作了报道和讨论.     

利用反射全息实现计算全息三维显示

计算全息和光学全息都可应用于三维显示,但各有自己的优势和缺陷.将计算全息和光学反射全息相结合,可以突破光学全息对记录物体的限制,进行虚拟物体或自然场景的全息图的制作,同时可以实现白光再现.本文首先用三维扫描仪获得实际物体的三维数据,用"点云算法"模拟得到其菲涅耳全息图透射率数据,采用计算全息打印机将其输出于全息记录介质,得到可光学再现的菲涅耳计算全息图H1.然后将H1作为光学全息的记录物体进行反射全息记录,将平面全息转化为体全息,实现了计算全息白光再现.     

轮廓仪在柱面镜检测中的应用

目前柱面镜检测的主要方法是样板比较法和干涉法。样板法对球面、柱面样板均有较高要求，而干涉法也需合适的高要求的辅助镜，并且对环境要求较严格。提出了用轮廓仪配用合适工装检测柱面镜的方法，该方法简洁、直观、快速，对环境要求较低。分析了该方法的检测误差，实验验证了分析的正确性，指出高精度轮廓仪在一定范围内能保证柱面镜的检测精度。这种方法不仅适用于零件的最终检测，也适用于加工过程中的检测。     

利用反射全息实现计算全息三维显示

计算全息和光学全息都可应用于三维显示,但各有自己的优势和缺陷.将计算全息和光学反射全息相结合,可以突破光学全息对记录物体的限制,进行虚拟物体或自然场景的全息图的制作,同时可以实现白光再现.本文首先用三维扫描仪获得实际物体的三维数据,用"点云算法"模拟得到其菲涅耳全息图透射率数据,采用计算全息打印机将其输出于全息记录介质,得到可光学再现的菲涅耳计算全息图H₁.然后将H₁作为光学全息的记录物体进行反射全息记录,将平面全息转化为体全息,实现了计算全息白光再现.     

Multiple-scattering speckle in holographic optical coherence imaging

We investigate the effect of multiple scattering on the image quality of holographic optical coherence imaging, which is a full-field coherence-domain imaging form of optical coherence tomography. The speckle holograms from turbid media and from multicellular tumor spheroids are characterized by high-contrast speckle on a multiply-scattered background caused by channel cross-talk. We quantify the multiple-scattered light that is accepted by the holographic coherence gate, and identify a cross-over from single-scattered to multiple-scattered light beyond 15 to 20 optical thicknesses. Speckle reduction relies on vibrating diffusers and on fast adaptive holograms in photorefractive quantum well devices. The high anisotropy factor for tumor tissue reduces multiply-scattered light contributions for biomedical tumor imaging.     

Methods of Fourier optics in digital holographic microscopy

In this paper, processing methods of Fourier optics implemented in a digital holographic microscopy system are presented. The proposed methodology is based on the possibility of the digital holography in carrying out the whole reconstruction of the recorded wave front and consequently, the determination of the phase and intensity distribution in any arbitrary plane located between the object and the recording plane. In this way, in digital holographic microscopy the field produced by the objective lens can be reconstructed along its propagation, allowing the reconstruction of the back focal plane of the lens, so that the complex amplitudes of the Fraunhofer diffraction, or equivalently the Fourier transform, of the light distribution across the object can be known. The manipulation of Fourier transform plane makes possible the design of digital methods of optical processing and image analysis. The proposed method has a great practical utility and represents a powerful tool in image analysis and data processing. The theoretical aspects of the method are presented, and its validity has been demonstrated using computer generated holograms and images simulations of microscopic objects.     

Autofocusing based on wavelength dependence of diffraction in two-wavelength digital holographic microscopy

An autofocusing method for two-wavelength digital holographic microscopy (TWDHM) based on the wavelength dependence of the diffraction process is proposed. Red and green lights are employed for the illumination of the TWDHM, and the generated holograms are recorded simultaneously by a color CCD camera. Due to the wavelength dependency of the diffraction process, the farther the reconstruction plane is from the image plane, the larger the difference is between the red and green light distributions. Thus, the image plane can be determined by finding the minimum of the variation between the red and green lights on their amplitude distributions. The feasibility of the proposed method is demonstrated by simulation and experiment.     

高质量全息光栅实验系统研究

基于全息光栅在信息光学及光谱仪中的重要地位,对全息光栅进行了理论分析,提出了一种新的制作高质量全息光栅的实验系统.该实验系统的优点在于:将激光器发出的高斯光束改造成为均匀平面光波,以此平面光波作为光源可以制作出高质量的全息光栅.     

Spatial frequency response and resolution in holography

Measurements were taken in order to compare “spatial frequency response” (SFR) and resolution properties of several types of holographic methods. The best SFR was obtained for the “Fourier holographic method”; good resolution and SFR were also found for the “image plane hologram” (IPH) reconstructed with a laser light.     

Non-gaussian image plane speckle: Measurements from diffusers of known statistics

The second and higher moments of intensity in non-gaussian image plane speckle patterns have been measured for deep phase screen diffusers. The diffusers were specially fabricated to have a gaussian distribution of phase with a standard deviation in the range 6–9 rad and a gaussian phase autocorrelation function of width ≈80 μm. Measurements of the second moment are in good agreement with the theoretical predictions of Jakeman and McWhirter     

Formation of the holographic image of a diffuse object in second-harmonic radiation generated by a nonlinear medium

Results of experiments on recording three-dimensional holographic images of extended diffuse objects using an SHG hologram generating the second harmonic are presented. In this case, the object image is formed by the second-harmonic radiation whose wavelength is smaller than the wavelength of object and reference waves recorded on a hologram by a factor of two. Elements of the theory of an SHG hologram are considered. A holographic image of a transparency object illuminated with diffuse light is obtained. It is shown that the resolving power of this image is close to the limit determined by diffraction effects. An experiment on defocusing the reconstructed image showed that it was localized in one spatial plane and, therefore, was three-dimensional.     

全息照相实验的新思路

在全息照相实验中,增加两种拍摄全息光栅的光路,在一张全息底片上,经过三次曝光,拍摄一幅全息图和两种光栅常量值的全息光栅,可使学生深刻地理解一张全息底片能够记录多个不同信息的原理。     

Formation of random and regular relief-phase structures on silver halide photographic emulsions by holographic methods

The formation of diffusers and microlens rasters on silver halide emulsions by holographic methods is considered. Two techniques for converting amplitude holographic recording to relief-phase recording, selective curing and irradiation of the emulsion gelatin by short-wavelength UV radiation, are compared.     

基于图像部分加入的数字全息水印技术

提出了一种以数字全息为基础的数字水印技术,实现了在原始图像中嵌入数字全息水印.考虑到传统的数字全息水印提取过程简单、易受攻击,为了提高水印信息的安全性,对传统的方法进行了改进.采用了图像部分加入的方法,将水印添加位置、水印图像大小和水印添加位置边缘像素作为水印提取密钥.实验证明,运用这种方法添加的水印具有较高的安全性.