电光调制实验系统的数字化研究

在激光出现以后，电光效应的研究和应用得到迅速的发展，电光器件被广泛应用，电光调制实验是大学近代物理实验中演示电光调制激光通讯的一个有效的综合性实验。根据电光效应的基本原理，在电光调制实验的基础上，使用 CCD 摄像头采集捕获通过晶体电光效应的光信息。通过 VFW、DirectShow、SDK 这三种常用的视频捕获技术的对比，选择采用 VFW 来实现视频捕获，阐述了 VFW 的工作流程。详细介绍了晶体锥光干涉图的成因，通过最小二乘法拟合光抽出露点的轨迹，计算光轴倾角，根据干涉图调整实验装置，使晶体的光轴始终保持与入射光方向平行，起偏器和检偏器偏振方向分别平行于晶体 x、y 光轴。利用 CCD 获取图片的平均灰度值来代替光强，绘制灰度的曲线图，测量出半波电压，编写相应的实现程序。为电光调制实验提供了一个分析工具，通过这个视频图像的采集分析系统使得实验数据更为准确。8327
关键词电光调制；锥光干涉图；CCD 摄像机；半波电压
Title    The Research on Digitized Transformation of
Electro-optical Modulation Experiment System
Abstract
According to the basic principles of electro-optic effect,base on the
electro-optical modulation experiment, the CCD camera is used for
acquiring and capture light through the crystal electro-optic effect.
Comparing three common video capture technology among DirectShow,
SDK,and VFW,the VFW video capture is chosen ,and VFW workflow is
expounded.The causes of crystal conoscopic interference pattern is
described in detail. The trajectory of the dew point is fitted by the
least squares fit, and the optical axis inclination can be calculated.
The experimental is setuped according to axis interferometry . The
crystal is always maintain a parallel with the incident direction, and
the polarization direction of the polarizer and the polarizer are
parallel to the crystal x, y axis. The average gray value of the
picture obtained by CCD is used to represent the light intensity.Gray
curve is drawn by the corresponding program to measure half-wave
voltage.It provides an analytical tool for the electro-optical
modulation experiment, and the video image acquisition and analysis
system allows a more accurate experimental data.
Keywords    Electro-optic modulator; conoscopic interferometry;CCD camera;
half-wave voltage 目   次
1 绪论. 1
1.1 研究背景.. 1
1.2 电光调制实验内容 1
1.3 半波电压的测量方法. 3
1.4 实验装置的不足及改进.. 4
1.5 本论文的主要内容 5
2   电光调制实验 . 6
2.1 电光效应.. 6
2.2 LiNbO3晶体的横向电光效应    8
2.3 实验系统设计    13
3 晶体的锥光干涉图    16
3.1 干涉图成因的理论分析. 16
3.2 成像特点. 17
3.3 测量光轴出露点及光轴方向 18
4 CCD 图像采集及数字图像处理软件的实现.. 22
4.1 成像系统设计 22
4.2 VC++软件坏境 22
4.3 VFW 开发包的简单介绍 . 23
4.4 最小二乘法拟合. 26
4.5 测量半波电压 27
结论 . 29
致谢 . 30
参考文献 .. 31 电光调制实验系统的数字化研究:http://www.youerw.com/wuli/lunwen_6614.html