共查询到17条相似文献,搜索用时 234 毫秒
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基于衍射理论 ,采用更接近光盘实际情况的椭圆型信息符模型并利用光盘的线性叠加原理得到光盘衍射模型的解析表达式 ,对三种主流盘片的盘片倾斜对循迹系统产生的影响进行定量的计算与分析。采用差动相位方式循轨的DVD ROM盘片随径向倾斜的偏移系数为 0 .0 6 μm/(°)。采用推挽方式循轨的DVD RAM盘片循轨误差随径向倾斜的偏移系数为 0 .15 μm/(°)。在相同的盘片参量情况下 ,差动相位检测方法获得循迹误差比推挽方法受盘片径向倾斜的影响更小 ,在读取过程中差动相位检测方法可以获得更好的伺服精度。分析了DVD RAM盘片预刻槽深度与循规误差信号受径向倾斜影响偏移量的关系。实验结果较好的验证了计算和结论。 相似文献
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杨妹清 《中国光学与应用光学文摘》2006,(6)
TP333.4 2006065153光学头安装误差对循迹信号的影响=Influence of optical pick-up assembly error on tracking signal[刊,中]/张建勇(清华大学国家光盘工程研究中心.北京(100086)),马建设…//光电子·激光.—2006,17(8).—953-957光学头的安装误差导致盘片轨道与光电探测器的切向轴线存在夹角,在光盘标量衍射模型的基础上,引入光 相似文献
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用矢量衍射方法分析了线偏振光入射到带有三环位相型光瞳滤波器的高数值孔径物镜时,焦点的轴向和横向光强分布.数值模拟结果表明,高数值孔径物镜聚焦时需同时考虑光强的轴向和横向分布.通过加入三环位相光瞳滤波器,在实现横向超分辨的同时实现了光学系统轴向焦深扩展和轴向光强分布平坦化,并且位相调制深度变化时,会出现轴向焦移现象.对三环位相光瞳滤波器结构进行了优化,得出了优化结果.
关键词:
光学超分辨
扩展焦深
位相型光瞳滤波器
矢量衍射方法 相似文献
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本文讨论由带支臂中心圆屏遮档圆形光瞳的衍射受限光学系统所成象的强度分布。讨论了支臂在光瞳面内和倾斜离开光瞳面两种情形的计算方法。实例计算表明,在支臂宽度相同条件下,两者的光强度分布之间具有不可忽略不计的差异。 相似文献
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提出一种基于琼斯光瞳的光刻投影物镜偏振像差检测方法。推导了基于琼斯矩阵的检测方程,建立了光强矢量与琼斯矩阵克氏积的线性关系,利用该线性关系直接检测琼斯光瞳形式的偏振像差。以一个典型的光刻投影物镜的琼斯光瞳为检测对象对所提方法进行仿真验证,仿真中考虑了偏振元件与CCD的实际参数误差,并与传统穆勒矩阵椭偏法转换得到的琼斯光瞳进行比较。对于同一种典型的偏振元件旋转角组合,与传统测量方法相比,所提方法测量的偏振衰减和偏振相位延迟误差均明显降低。仿真结果表明,所提方法在不增加现有测量装置复杂度的基础上,明显提高了琼斯光瞳形式偏振像差的测量精度。 相似文献
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光瞳截断作用对纯位相调制激光束整形系统的系统性能有重要影响. 本文提出了一种关于光瞳半径对近场调制位相和远场系统评价函数影响的定量分析方法. 通过拉格朗日乘数法等方法分析光瞳半径对近场调制位相的影响, 结果表明: 近场调制位相随光瞳半径近似线性增加. 通过建立数学模型, 拟合分析光瞳半径对系统评价函数的影响. 结果表明: 对方形目标光强, 系统评价函数拟合精度确定系数达到99%左右, 光瞳半径为2.5倍高斯光束束腰半径时, 相关系数达到0.997, 光强偏离残差平方均值达到0.0004左右, 光瞳截断作用趋于最小; 对圆形目标光强, 系统评价函数拟合精度确定系数达到97%, 光瞳半径为3倍高斯光束束腰半径时, 相关系数与光强偏离残差平方均值变化幅度均在10-3量级, 系统评价函数趋于收敛, 光瞳截断作用趋于最小. 相似文献
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提出了一种采用倾斜脉冲的级联二阶非线性来实现超短激光脉冲压缩的方法. 对基于单块BBO晶体中基频光与倍频光群速度匹配的级联二阶非线性的脉冲压缩方案进行了理论分析. 对比研究了群速度匹配与失配情况下利用级联二阶非线性进行脉冲压缩的效果, 并模拟分析了基频光与倍频光的位相失配量、非线性晶体长度、 基频光初始峰值光强和初始脉宽等因素对脉冲压缩效果的影响. 结果表明, 基频光与倍频光的群速度匹配将会大幅度改善压缩脉冲的时间波形和频谱分布. 通过对位相失配量、晶体长度、初始光强等参数的优化和选取可获得较理想的压缩效果. 采用倾斜脉冲的级联二阶非线性的脉宽压缩方法, 针对中心波长800 nm、脉宽100 fs, 峰值光强为50 GW/cm2的基频光脉冲, 采用25 mm厚BBO晶体, 当基频光与倍频光位相失配量Δk=60 mm-1(对应失谐角1.98°), 晶体外部脉冲前沿倾斜角γ0=74°时, 计算获得了质量较好的20 fs剩余基频光, 并同时产生了14 fs的倍频光.
关键词:
倾斜波
级联二阶非线性
群速度失配
脉冲压缩 相似文献
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We present the validity of in-line-type differential push-pull methods using segmented gratings with respect to arrangement
errors by numerical calculation for the first time. In these differential push-pull methods, the segmented gratings for generating
subspots are divided into more than two regions, each with a specific width and a specific phase value, and are ideally arranged
on the optical axis. We calculate tracking error signals in these methods with respect to the arrangement errors against the
optical axis under parameter conditions of the widths of the segmented regions of the gratings. The obtained results show
that the grating with a simpler configuration with two regions reveals good compatibility between DVD-recordable (DVD-R) and
DVD-random access memory (DVD-RAM) compared with those with three or four regions, when the arrangement error is less than
10% of the radius of the incident laser beam. 相似文献
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根据夫琅和费衍射理论,建立了四路激光相干合成模型,研究了不同占空比条件下倾斜相差对激光相干合成效果的影响。通过欧拉旋转变换,将各子光束的倾斜角度转换成相应的倾斜相差引入到光束合成模型中。仿真计算了不同占空比、不同倾斜角度情况下合成光束在远场的光强分布,分析了占空比、倾斜角度对远场光强分布的影响。仿真结果表明,随着子光束倾斜角度的增大,远场艾里斑内的光强逐渐减小,合成效果变差。仿真计算了不同占空比条件下桶中功率(PIB)和β因子随倾斜角度的变化关系。仿真结果表明,随着子光束倾斜角度的增大,PIB和β因子两个评价指标均逐渐变差。为了达到一定的评价指标要求,必须利用快反镜等校正器件将各子光束的倾斜角度减小到一定的范围之内。 相似文献
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A new tracking error detection method using amplitude difference detection for signal waveform modulation multi-level discs 下载免费PDF全文
The sub-land/sub-pit affects the characteristic of the tracking error signal which is generated by the conventional differential phase detection (DPD) method in the signal waveform modulation multi-level (SWML) read-only disc. To solve this problem, this paper proposes a new tracking error detection method using amplitude difference. Based on the diffraction theory, the amplitude difference is proportional to the tracking error and is feasible to be used for obtaining the off-track information. The experimental system of the amplitude difference detection method is developed. The experimental results show that the tracking error signal derived from the new method has better performance in uniformity and signal-to-noise ratio than that derived from the conventional DPD method in the SWML read-only disc. 相似文献
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In this paper, we present the validity of in-line-type differential push-pull methods using segmented gratings with respect
to the radial shift of an objective lens by numerical calculation for the first time. In these differential push-pull methods,
the segmented gratings for generating sub spots are divided into two to four regions each with a specific phase value and
a width. Tracking error signals are calculated with respect to the objective lens shift under parameter conditions of the
widths of the segmented regions. The obtained results show that the grating of the simpler configuration with two regions
reveals good compatibility between DVD-R and DVD-RAM compared with those with three or four regions 相似文献
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Liying Tan Qingbo Yang Jing Ma Siyuan Yu Qiqi Han Yijun Jiang 《Journal of Russian Laser Research》2011,32(3):209-215
We analyze the performance of a satellite-to-ground downlink coherent lasercom system taking into account the combined effects
of atmospheric wavefront aberration and tracking error of the receiver. We revise the wavefront phase variance in the case
where the tracking error of the receiver terminal is present. We consider the example of the BPSK modulation scheme and show
that the tracking error of the receiver terminal greatly increases the bit error probability of the coherent system. We show
the optimum aperture diameter of the receiver. This study can benefit the satellite-to-ground downlink coherent lasercom system
design. 相似文献
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In this paper, a new opto-digital stereo object tracking system using the variable window mask and the optical binary phase extraction joint transform correlator (BPEJTC) is proposed. At the first step, with the distance information from the stereo camera to the tracking object easily acquired by the structural elements of a stereo vision system, the area of the tracking object can be digitally extracted by using the variable window mask. And, at the second step, by carrying out the optical BPEJTC between this reference image obtained from the variable window mask and the stereo input image, the coordinates of the tracking object's location can be acquired, and then with these values, the convergence angle and the pan/tilt of the stereo tracking camera can be finally controlled. From some experimental results, the proposed system is found to be able to effectively extract the area of the target object from the input image having the background noises by using the variable window mask. And, with the location values of the tracking object obtained by using the optical BPEJTC, the convergence angle and the pan/tilt of the stereo cameras can be controlled. Finally, a feasibility of real-time implementation of the adaptive stereo object tracking system using the proposed algorithm is also suggested. 相似文献