1、中文 2477 字 毕业设计 说明书 英文文献及中文翻译 学生姓名： 学号： 学 院： 专 业： 指导教师： Novel Optical Sensor for Precise Tilt Angle Measurement Fan Hua, Ivan Reading and Fang ZhongPing Singapore Institute of Manufacturing Technology Nanyang Avenue 71, Singapore 638075, Email: hfansimtech.a-star.edu.sg ABSTRACT A novel optical senso
2、r, which can measure inclination angle or tilt angle of two axes simultaneously and precisely, is introduced. This sensor is based on the principle of laser interference so it has very high accuracy. A prototype sensor is designed, built and evaluated to demonstrate the novel concept. It is an optoe
3、lectronic sensor. There are no moving parts in the sensor. A fluid horizontal that is absolutely perpendicular to the true vertical provides the reference plane. The angle between the sensor and the absolute horizon changes with the inclination of the object being measured. These changes are reflect
4、ed in the way of fringe patterns centre position shift. Different interference patterns centre locations are generated when tilt angle varied. The interference fringe pattern are recorded and processed to translate into the tilt angles of two axes, horizontal and vertical. The accuracy can reach as
5、high as +/- 1 arc second with the measurement range of 700 arc seconds when 1024 by1024 pixels image sensor is utilized. Key words: tilt angle sensor, inclinometers, laser interference I. INTRODUCTION There are several kinds of commercial sensor for tilt angle measurement, which are available in the
6、 market. Some known as tilt angle sensor, some are known as inclinometers. They base on different working principles. Electrolytic liquid 1, capacitance 2 and pendulum 3 are the three main working principles that most tilt angle sensor or inclinometer usually base on. Here we propose a novel optical
7、 method and build up an optoelectronic sensor with laser, optical components and image sensor. It can do precise tilt angle measurement simultaneously. There is no mechanical movement part. The working principle is based on optical interferometry. Coherent laser is used as the lighting source. It wi
8、ll go through a liquid oil box, which is built by a glass container filled with liquid oil. A fluid horizontal that is absolutely perpendicular to the true vertical provides the reference plane. When laser beam pass through the oil box two beams are reflected back by surface of the liquid and contai
9、ner glass. Interference fringes are formed with these two beams. The fringe patterns will shift in corresponding to the changes of the tilt angles. The fringe patterns is captured and processed to give the tilt angle information. Optical working principle makes it insensitive to magnetic field. The
10、sensor can measure two axes inclination angle simultaneously. A fluid horizontal make sure the reference plane is an absolute horizontal plane. High sensitive optical interference measurement principle assures the high accuracy. A prototype of the method has been built up and evaluated. Experimental
11、 results show the tilt angle changes relative to sea level can be detected at the accuracy of +-1 arc second within the measurement range of 700 arc seconds. II. PRINCIPLE Figure 1 illustrates the schematic diagram of working principle. Point O is the focal point of beam expanding lens. Point O can
12、be considered as a point light source. It emits spherical wave-front. Liquid oil surface will always maintain horizontally due to the gravity force of the earth. The oil surface is used as the reference plane. The container is made of glass. Its bottom surface will incline together with the target o
13、bject when the sensor is placed on the target. The light from oil surface and glass surface will interference to form circular fringes pattern (see Fig. 4). The incline angle can be measured with the centre position changes of circular fringes. P is the mirror image of O against to glass-air surface and Q is the mirror image of O against to oil-air surface. The oil-air surface represents the horizontal plane. When the glass surface positioned parallel with oil surface the P and Q are in the same line
