Light source system for high-precision flat-field correction and the calibration of an array detector

Signal distortion due to the non-uniform response of the detector degrades the measurement accuracy of most metrology instruments. In this Letter, we report a newly developed calibration source system for reference-based non-uniformity correction using a laser source, a fiber, and a diffusive module. By applying the Monte Carlo simulation, we show that the transmittance of the system highly depends on the cavity reflection of the diffusive module. We also demonstrate the use of this system to achieve a flat field at a very low non-uniformity(less than 0.2%) with proper illumination intensity, which most costly commercial integrating sphere systems traditionally cannot provide.     

Speckle analysis in laser scanning display system

The theory of speckle formation in laser scanning display system is established based on the averaging effect of eye response as laser beam scanning through an eye resolution spot. It is analyzed that speckle reduction can be obtained by averaging states of speckle during scanning. The theoretical results show that a smaller correlation length of screen surface and the narrowing of laser beam in scanning direction can reduce speckle contrast for this system.     

立体显示技术的研究进展

介绍了非全息三维显示技术,对双眼视差（佩戴眼镜、裸眼）、非双眼视差的立体显示技术进行了评述。讨论了图书、高清液晶显示和激光显示等应用中的三维显示技术的最新进展。     

五角棱镜光学平行差的理论分析

利用矩阵光学方法,计算得出五角棱镜两种光学平行差的解析表达式,分析五角棱镜光学平行差与工作面法向矢量夹角的矩阵关系.基于Agilent激光干涉仪角度测量系统和DHC三维转台搭建实验装置,测量了Thorlabs五角棱镜的两种光学平行差.实验和解析式计算结果偏离度不超过4%.五角棱镜滚动角、偏摆角的变化等效于五角棱镜光学平行差的变化.通过坐标系变换,五角棱镜的自身误差和系统在线测量误差可以被同时标定.该研究对五角棱镜的实际加工、测量系统标定,以及高准确度面形检测提供了参考.     

Single 3D laser projector with speckle suppression

In this letter, a new single three-dimensional （3D） laser projector is proposed. As liquid crystal （LC） can produce two image patterns with orthogonal polarization states at 120 Hz, only one projector is required in this approach for reconstruction of a 3D object. The light source is made up of RGB （red, green, and blue） lasers because laser has lots of advantages such as longer life, higher brightness, and larger color gamut. A novel diffusive media with good polarization-maintaining quality is used as rear projection screen for its high transmission efficiency （-90%） and low reflection efficiency. When laser incidents into the diffusive media, which contains lots of spherical particles with sizes between 2 and 15 μm, laser is scattered randomly and the laser speckle is reduced. A spatial phase mask is also inserted into the optical path to reduce speckle. With these techniques, the speckle contrast is reduced to 0.1 and the quality of image oatterns has been greatlv imoroved.     

基于X射线近场散斑的波前检测技术研究现状

第四代同步辐射光源为多个研究领域提供了亮度和相干度更高、性能更加优异的X射线。为了充分发挥这些光束的潜力,需要精确的光束线装调和高质量的X射线光学元件。波前检测技术在这些方面发挥着重要作用。近10年来快速发展起来的基于X射线近场散斑的波前检测技术,具有简便易行、测量精度高等优点。利用散斑在深菲涅耳区形状和大小不变的特性,在参考图和样品图之间进行互相关计算,提取出入射波、待测光学元件透射波或反射波的波前信息。综述了利用X射线近场散斑开展波前检测的研究现状,介绍了X射线散斑追迹技术、X射线散斑向量追迹技术、X射线散斑扫描技术、自相关X射线散斑扫描技术、通用调制图样分析技术和Ptychographic X射线散斑追迹技术的原理、实验流程,以及各自的优势和应用。     

激光光斑形状和尺寸对扫描显示中散斑对比度的影响

计算了圆形、矩形激光光斑对于激光扫描显示系统中散斑对比度的影响.对于圆形光斑,当光斑尺寸大于散射表面相关长度时,得到的散斑对比度随着光斑尺寸变小而下降;当光斑尺寸接近表面相关长度大小时,由于光斑中包含的散射颗粒变少,得到的是非高斯散斑,散斑的对比度反而会变大;随着激光斑进一步变小,由于镜面反射效果散斑的对比度会很快下降.对圆形光斑部分结果给出了实验验证.为了保证光斑中有足够的散射颗粒,只在一个方向压窄光斑,分别计算了平行于扫描方向和垂直于扫描方向压窄光斑得到的散斑对比度.平行于扫描方向压窄光斑,散斑的时间相关性会下降,平均效果变明显,散斑的对比度变小;垂直于扫描方向压窄,散斑对比度变化不大.