利用四棱锥传感器检测光学拼接镜的法向光程差

研制光学天文望远镜拼接主镜时,需要精确检测各子镜单元之间的法向光程差.在对四棱锥波前检测原理分析的基础上,通过反射立方体模拟拼接镜面,开展四棱锥传感器的检测实验,验证了四棱锥传感器检测信号和拼接镜子单元间的piston误差信号之间存在确定的函数关系.在一个波长的位移行程内,目前可以达到数十纳米的测量精度.     

空间望远镜展开机构地面试验系统设计

为满足空间探测对大口径空间望远镜的需求,验证拼接主镜展开机构的合理性,测试镜面展开的重复定位精度,设计了一种空间望远镜展开机构地面实验系统。该系统由服务器上位机、控制子系统、驱动子系统和图像采集子系统构成,每个驱动子系统具有唯一的地址,其接收控制子系统的命令,驱动展开机构镜面模组进行运动,并实时回传镜面模组的状态和位置信息,控制子系统除完成服务器上位机命令的分解并下发给各个驱动子系统外,还汇总和处理各个驱动子系统反馈的数据并上传给服务器上位机。服务器上位机接收控制子系统上传的数据并显示,且解算从各图像采集子系统获得的镜面模组展开到位图像信息并显示出镜面的位姿信息,测试表明,该系统能有效完成拼接主镜空间望远镜展开机构的重复性展开和收拢,且重复位移定位精度小于0.05mm,姿态角度小于0.02度,能够满足空间望远镜展开机构结构简单、稳定可靠和精度高等要求。     

单晶硅压力传感器技术进展

<正> 硅材料可分为单晶硅、多品硅和非晶硅。从结构上来说,单晶硅最简单,非晶硅最复杂。用这三种材料都可以制造压力传感器。这些压力传感器大致可以分成四种形式,即压阻式、电容式、MOS式和薄膜式。前三种主要以单晶硅制造,后一种主要以多晶硅和非晶硅制造。目前制造压力传感器仍以单晶硅为主,但从发展趋势来看似有向多品与非晶的薄膜式方向进展的势头。     

微型计算机与传感器技术讲座(四)

第五讲位移传感器根据位移的特征,可分为线位移和角位移。线位移是指机构沿着某一直线移动的距离,所以,线位移的测量又称长度测量。一、线位移传感器根据传感器的变换原理,常用的线位移传感器有电位计式位移传感器、电感式位移传感器、差动变压器式位移传感器、电容式位移传感器、感应同步器以及磁栅、光栅、激光位移传感器等。根据输出信号,位移传感器可以分为模拟式和数字式两种。     

空间望远镜自适应光学控制系统的模型框架研究

作为一种空间和地面探测的研究手段,空间望远镜起着越来越重要的作用.为了获得较高的分辨率,空间望远镜的口径要随之加大,由此出现了一系列相关的技术问题.自适应光学技术的出现和应用,使空间望远镜的设计思想有了一个飞跃.而James Webb望远镜的出现又提出了更新的挑战.该文对James Webb望远镜自适应光学控制系统的结构层次进行了划分,在说明其自适应光学控制系统原理的基础上,对空间望远镜的工作原理做了分析.建立了主镜镜面展开过程的动力学模型,最后建立了空间望远镜整个控制系统的模型框架.     

霍尔效应磁敏传感器及其应用

介绍了霍尔传感器的原理、分类及应用,其中有开关型及线性型等,它们与光电式、电容式、电感式传感器相比较具有诸多特点,是今后应用较多的一种传感器.     

基于PZT的法珀滤光器平板平行度控制系统的设计与实现

主要介绍以HPV系列压电陶瓷驱动电源为核心的法珀滤光器平板平行度控制系统。该系统包括电容式边缘传感器支持电路、压电陶瓷、压电陶瓷控制电源、计算机及其接口电路。该控制系统可以实现伺服控制,其软件可扩展,可移植性比较强。通过对软件扩展和硬件调整,该控制系统可以直接应用于大型拼接望远镜面型控制。     

采用固态传感器技术的硅谐振变送器

在过程控制领域里，在各类控制系统配套的检测仪表中，流量、压力、液位的检测，主要是采用差压、压力变送器（目前虽然各种流量仪表在发展，但孔板等节流装置加差压变送器的检测仪表在实际应用中仍占三分之一以上人随着技术的进步，差压。压力变送器也在不断更新换代，其工作原理也由位移式、力平衡式、扩散硅电阻应变式、电容式而发展成现在采用固态传感器技术和微细加工技术的各种固态化的智能式变送器。本文将结合日本横河公司的硅谐振式的EJA系列变送器进行阐述。固态传感器技术又称物性型传感器技术，它与原来的结构型传感器技术有…     

LVDT差动变压器式线性位移传感器的现状和动态

<正> 一、概述 线性位移传感器即是将被测物体作直线运动时的位移量转换为电量或其他可测量的器件,它在各种机械量位移的检测及科研部门中有着广泛的应用。线性位移传感器种类较多,常见的传感器形式有:充电式、电感式、电容式、光栅式等,另外     

可拼接式全柔性电容触觉阵列传感器设计与实验

针对现有机器人触觉传感器存在可穿戴性与可移植性差、不易维护及扩展等缺点,提出了一种可用于机器人仿生皮肤的全柔性电容式触觉传感器,并设计成12×12正方形触觉传感阵列和正六边形触觉模块两种可拼接式阵列结构.以炭黑填充硅橡胶作为电容式触觉传感器的弹性电介质,聚酰亚胺为柔性基体,有机硅导电银胶和金属膜为上下两柔性极板,共同构成压力敏感单元.介绍了电容式柔性触觉传感器的工作原理、结构设计及两种与之对应的电容触觉阵列无线数据采集与处理系统.实验结果表明,该全柔性电容式触觉阵列传感器及信号提取系统具有良好的稳定性与灵敏度,可用作人工皮肤实现全触觉感知.     

浅析唐代瑞兽葡萄镜纹饰的艺术特色与审美思想

唐代是铜镜发展的鼎盛时期。瑞兽葡萄镜是唐代最典型的铜镜品种,以瑞兽和葡萄枝蔓组合为纹饰主题,体现了唐代艺术文化的繁荣昌盛和兼收并蓄。本文从唐代瑞兽葡萄镜的纹饰题材入手,分析了其纹饰的艺术特色,并且对其审美思想进行了论述。     

Rapid communication Effects of driver-side mirror type on lane-change accidents

This quasi-experiment was designed to investigate the effects of the type of driver-side mirror on lane-change accidents. The analysis was based on 407 accidents reported from 1987 to 1992 to Finnish insurance companies, for vehicles with passenger-side convex mirrors and one of three types of driver-side mirrors (flat, convex or multiradius). The results showed that there was no difference between the multiradius and convex mirrors in the frequencies of lane-change accidents to the left. Compared to the flat mirror, the mean effect of the multiradius and convex mirror was a 22% decrease. However, the statistical strength of the data was low; 95% confidence interval ranged from a 51% decrease to a 25% increase. This result was not related to driver characteristics or driving conditions. In conclusion, the multiradius and convex driver-side mirrors, in comparison to the flat mirror, are more likely to reduce than increase lane-change accidents. A theoretical implication of this study is that minimizing the blind spot is likely to be more important than providing an undistorted image of objects. From a practical point of view, the present findings support the use of multiradius and convex driver-side mirrors.     

A Theory of Single-Viewpoint Catadioptric Image Formation

Conventional video cameras have limited fields of view which make them restrictive for certain applications in computational vision. A catadioptric sensor uses a combination of lenses and mirrors placed in a carefully arranged configuration to capture a much wider field of view. One important design goal for catadioptric sensors is choosing the shapes of the mirrors in a way that ensures that the complete catadioptric system has a single effective viewpoint. The reason a single viewpoint is so desirable is that it is a requirement for the generation of pure perspective images from the sensed images. In this paper, we derive the complete class of single-lens single-mirror catadioptric sensors that have a single viewpoint. We describe all of the solutions in detail, including the degenerate ones, with reference to many of the catadioptric systems that have been proposed in the literature. In addition, we derive a simple expression for the spatial resolution of a catadioptric sensor in terms of the resolution of the cameras used to construct it. Moreover, we include detailed analysis of the defocus blur caused by the use of a curved mirror in a catadioptric sensor.     

Silicon microoptical mirrors to make close parallel beams with conventional laser diodes

We have fabricated two kinds of silicon microoptical mirrors to make optical axes of two high-power laser diodes close at an interval of 100 /spl mu/m, utilizing anisotropic etching of silicon with the self-alignment mask. One of them is a microrectangular prism mirror (MRPM). It has two orthogonal reflection mirrors, composed of polished [110] and anisotropically etched (111) planes of silicon. The other is a micro two-reflection mirror (MTRM). It has two pairs of two reflectors facing each other in parallel. The use of MTRM made the mounting process easier than that of MRPM. The use of the self-alignment mask made mirror surface smoother and it has been confirmed that full widths at half maximum (FWHM) are almost the same with and without reflections by MRPM or MTRM, respectively. It has also been shown that the etched (111) plane has the etching-condition dependence of surface roughness.     

Arrays of large-area, tip/tilt micromirrors for use in a high-contrast projector

Arrays of two-degree of freedom analog micromirrors are designed for use within an high-contrast projector and fabricated using a multi-user MEMS fabrication process. We demonstrate a novel way of optimizing the tradeoffs between tilt angle and mirror size by subdividing the mirrors into smaller functional subsections that move synchronously. The mirror design employs multiple mirrors within a gimbal frame. The frame rotates around one axis, and each mirror within the frame rotates around a perpendicular axis, resulting in two-degree of freedom rotation. The design employs specific electrode shapes to allow one-layer connections. Using these fabricated mirrors, simultaneous actuation of mirrors within a composite structure is achieved. A prototype array of fabricated mirrors is described, with 6 × 5 mirrors each of 160 μm × 160 μm forming one composite mirror of an array, giving total active area of 960 μm × 800 μm. The mirrors can achieve a maximum tilt angle of 2.25°. The fill factor of this design is 68%.     

Fabrication of 45° mirrors together with well-defined v-groovesusing wet anisotropic etching of silicon

The most commonly used microstructure for passive fiber alignment is the ordinary v-groove, defined by {111} planes on a (100) silicon wafer. The plane at the end of the groove, having a 54.7° angle to the surface, can be used as a reflecting mirror. For single-mode fiber applications, a 45° mirror is advantageous together with high accuracy in the position of the fiber, i.e. a smooth mirror and good control of the groove geometry is needed. Two techniques are presented to form 45° mirrors along with well-defined grooves in silicon, using the wet anisotropic etchants EDP and KOH. These techniques are used: (1) to reveal {110} planes on (100) silicon and (2) to make {111} mirrors on wafers that are cut 9.7° off the [100] axis. On (100) silicon, EDP without pyrazine gave the best result. The best mirror and groove reproducibility was found on off-axis cut silicon, using 36 wt.% KOH, with isopropyl alcohol added     

电容过程成像中电容测量方法的比较研究

电容过程成像系统所测量的电容变化量非常微弱,极难检测,且总的杂散电容值又远 大于待测电容, 本文分析了ECT系统中四种微小电容检测电路--带反馈补偿的交流测量电路 ,自平衡电容测量等电路,并比较了它们的优缺点．     

3-D reconstruction using mirror images based on a plane symmetryrecovering method

Three-dimensional reconstruction from a perspective 2D image using mirrors is addressed. The mirrors are used to form symmetrical relations between the direct image and mirror images. By finding correspondences between them, the 3D shape can be reconstructed by means of plane symmetry recovering method using the vanishing point. Two constraints are used in determining the correspondence. In the case where only one mirror is used, invisible parts both in the direct image and in the mirror image may still remain. Using multiple mirrors, however, occluded parts will decrease or disappear, and occlusion-free object reconstruction becomes possible     

Depth‐enhanced integral‐imaging 3D display using different optical path lengths by polarization devices or mirror barrier array

Abstract— Depth‐enhanced integral three‐dimensional (3D) imaging using different optical path lengths by using a polarization selective mirror pair or mirror barrier array is proposed. In the proposed approach, the enhancement of image depth is achieved by repositioning two types of elemental image planes, thus effectively two central depth planes are obtained. One of the two implementation methods makes use of the two‐arm structure that has different optical path lengths and polarization‐selective mirrors. The other utilizes the mirror barrier array. The primary advantage of the method with polarization devices is that we can observe 3D images that maintain some level of viewing resolution with a large depth difference without any mechanical moving part. The mirror barrier array has the advantage of the compact thickness. We demonstrated and verified our proposals experimentally.     

Convex rear view mirrors compromise distance and time-to-contact judgements

Convex rear view mirrors increasingly replace planar mirrors in automobiles. While increasing the field of view, convex mirrors are also taken to increase distance estimates and thereby reduce safety margins. However, this study failed to replicate systematic distance estimation errors in a real world setting. Whereas distance estimates were accurate on average, convex mirrors lead to significantly more variance in distance and spacing estimations. A second experiment explored the effect of mirrors on time-to-contact estimations, which had not been previously researched. Potential effects of display size were separated from effects caused by distortion in convex mirrors. Time-to-contact estimations without a mirror were most accurate. However, not distortion, but visual angle seemed to cause estimation biases. Evaluating advantages and disadvantages of convex mirrors is far more complex than expected so far.