Research Of Micro Angular Displacement Sensing With The Application Of Planar Waveguide Technology

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...