【作者】 舒建伟；

【导师】 曹庄琪；

【作者基本信息】 上海交通大学 ， 光学， 2007， 硕士

【摘要】 在许多情况下,对某些转动部件的角位移进行实时精确测量具有重要的实际意义。在目前的工业应用中,传统的电磁式角位移传感器仍占有重要的地位,但是这些电磁式检测手段由于各种局限,其测量分辨率难以进一步提高,因而无法满足许多高灵敏度测量的需要。随着稳定的激光光源的发展,各种新型光学测角方法也应运而生。由于光学测角法普遍具有非接触、高准确度和高灵敏度的特点,因而越来越受到人们的重视。目前分辨率达到几个纳弧度量级的光学测角法已有报导,但随之而来的一个问题是各种误差因素对测量结果的影响会变得十分显著,因而该方法对传感器件的加工制作提出了极高的要求,大大增加了制作成本。本文在对平面波导中的超高阶导模进行研究后,提出了一种新型的微小角位移测量方法。该法基于一种亚毫米金属包覆波导结构,研究表明这种波导中的超高阶导模对导波层的折射率、厚度以及激光的波长均十分敏感,因而是一种很好的传感探针。若通过棱镜耦合的方式激发空气导波层中的超高阶导模,则当被测部件发生微小偏转时,空气层厚度和导模的有效折射率也因此改变,从而引起耦合光束的反射光强急剧变动,其变动幅度与部件的角位移量近似成正比关系,而通过波导的衰减全反射曲线可以求出两者的比例系数。理论和实验均表明这种方法可以实现几个纳弧度的测量分辨率;尽管如此,该法对测量装置的制作精度并不需要特别高的要求,因而在极小角位移测量中具有独特的应用价值。更多还原

【Abstract】 In many cases, the precise real-time measurement of angular displacement of certain components is vital in practical applications. While the electro-magneto types of angular displacement sensor still have a significant position in the industrial world nowadays, their intrinsic limitations disqualify them for use in high-sensitivity detections, as far as their not-so-advanced resolution is considered.With the development of lasers with high stability, various optical methods for angular measurement came into being and are now catching increasing attractions for their general characteristics such as noncontact, high precision & resolution, etc. An optical sensor with resolution up to several nano-radians has been reported recently. This type of sensor, however, comes along with a remarkable disadvantage that the various error factors of the detector have quite an impact on the measuring results, thus is difficult to fabricate and of high cost.Based on the research of ultra-high order modes in sub-millimeter metal-cladding waveguides, this thesis presents a new approach for micro angular displacement sensing. These investigated ultra-high order modes are proved to be very sensitive to the refractive index and thickness of the guiding layer as well as to the laser’s wavelength, therefore can serve as fine sensitive probes. In the measurement these modes can be excited in the air gap through prism coupling. Once a micro angular displacement更多还原