毕业设计论文 外文文献翻译 光信息科学与技术 光电目标位置和速度测量系统 中英文对照.doc

毕业论文英文文献及中文译文学生姓名： 学号：0506340345 学 院： 信息与通信工程学院 专 业： 光信息科学与技术 指导教师： 2009年 6 月中北大学2009届毕业论文Electro-optical target system for position and speed measurementAbstractThis paper introduces an electro-optical target system(EOTS) covering the speed range from subsonic to supersonic. This microcomputer-based system has a novel structure and shows the capability of precisely detecting the position as well as the velocity of small caliber projectiles in real time. A prototype EOTS whose target area is 1m2 has been constructed and tested. A speed accuracy of better than 0.3% was achieved. A position accuracy, mainly dependent on the spacing between photodiodes in EOTS, of better than 1mm on a target area of 1m2was also accomplished.Keywords: External ballistics, No contact measurement, Electro-optical techniques, Position measurement, Speed measurement1 IntroductionThe speed and position measurements of projectiles are two important items in ballistic research. To determine these parameters precisely one needs an accurate measuring system. A conventional method, namely the hanging up(and taking down) of target discs[l], though accurate in position measuring, is time consuming. A shot-position indicator(SPI), described in Reference 2, can measure the position of a high speed projectile by acoustic measurement. However, the SPI does not provide the speed information; neither does the conventional method. Besides, the SPI is used within the limits of supersonic projectiles.To measure the speed and position of projectiles rapidly and simultaneously, different electro-optical based systems have been proposed 3-5]. These systems have the ability to cover the speed range from subsonic to supersonic. One system, called the target measurement system(TMS)[3], uses vertical and horizontal banks of light sources to form two perpendicular light grids that construct the target area. Another system, called the electro-optical projectile analyzer[4], uses the same principle as TMS, but simplifies light sources with fiber optics bundles and a single light source in each light grid. The other system, called the electronic yaw screen(EYS)[5], uses a solid state laser that is collimated and directed to a one-dimensional beam expander system to form a fan-shaped light screen. This light screen then is reflected by a mirror to construct a portion of the target area. The light screen is more precise than the light grid because there is no dead zone in the target area as with the light grid system.From the aspect of speed and position measurement, we take advantage of the above systems and propose a novel system; the electro-optical target system(EOTS)[6]. We use a cylindrical mirror that reflects the incident laser beam into a 90º fan-shaped light screen. Two such light screens construct a two-dimensional positioning system. We even propose a bent cylindrical mirror to generate a 90º light screen with a few degrees extended in a direction normal to the light screen to reduce the sensitivity to vibrations.A prototype EOTS, whose target area is 1m2 and measured speed range is from 50m/s to 1200m/s, has been constructed and tested. A speed range of up to 5000m/s can also be expected according to the simulation results from the electronic circuit using PSpice[7]. Finally, a nine-point testing result from a 0.38in. pistol is shown in this paper. The result shows that the standard deviation of position accuracy is less than 1mm.2 Basic principle of EOTSFig. 1 shows the optical configuration of EOTS. A laser beam from a He-Ne laser is directed onto a cylindrical mirror. The reflected laser beams create a fan-shaped light screen and are directed onto photodiodes that are neatly arranged into an L-shaped photodiode array. EOTS uses two laser sources, two cylindrical mirrors and two photodiode arrays, which are arranged on the opposite sides of the EOTS body to form two fan-shaped light screens. Each light screen is combined with its own signal processing circuit to construct an optical gate. Although there is a distance between the two parallel light screens, viewed from a distance point, these fan beams intersect in a region of space called the target area (Fig. 2). A projectile can be measured only if it travels through this target area.Fig. 1 Optical configuration of EOTSFig. 3 shows the shot position of the projectile is calculated. The target area, for the convenience of illustration, is a square of dimension D on each side. The number of photodiodes on the L-shaped photodiode array is 2N. Each photodiode is numbered in order, as shown in the figure. For illustration clarity, only the photodiode array and the cylindrical mirror of the first optical gate are shown. The projectile is considered to be incident normally to the first and to the second optical gate in sequence. When the projectile blocks the light scre。