激光测距-外文翻译

Laser rangefinder A long range laser rangefinder is capable of measuring distance up to 20 km; mounted on a tripod with an angular mount. The resulting system also provides azimuth and elevation measurements. A laser rangefinder is a device which uses a laser beam to determine the distance to an object. The most common form of laser rangefinder operates on the time of flight principle by sending a laser pulse in a narrow beam towards the object and measuring the time taken by the pulse to be reflected off the target and returned to the sender. Due to the high speed of light, this technique is not appropriate for high precision sub-millimeter measurements, where triangulation and other techniques are often used.Pulse The pulse may be coded to reduce the chance that the rangefinder can be jammed. It is possible to use Doppler effect techniques to judge whether the object is moving towards or away from the rangefinder, and if so how fast.Precision The precision of the instrument is determined by the rise or fall time of the laser pulse and the speed of the receiver. One that uses very sharp laser pulses and has a very fast detector can range an object to within a few millimeters.Range Despite the beam being narrow, it will eventually spread over long distances due to the divergence of the laser beam, as well as due to scintillation and beam wander effects, caused by the presence of air bubbles in the air acting as lenses ranging in size from microscopic to roughly half the height of the laser beams path above the earth.These atmospheric distortions coupled with the divergence of the laser itself and with transverse winds that serve to push the atmospheric heat bubbles laterally may combine to make it difficult to get an accurate reading of the distance of an object, say, beneath some trees or behind bushes, or even over long distances of more than 1 km in open and unobscured desert terrain. Some of the laser light might reflect off leaves or branches which are closer than the object, giving an early return and a reading which is too low. Alternatively, over distances longer than 1200 ft (365 m), the target, if in proximity to the earth, may simply vanish into a mirage, caused by temperature gradients in the air in proximity to the heated surface bending the laser light. All these effects have to be taken into account.Calculation The distance between point A and B is given byD=ct/2where c is the speed of light in the atmosphere and t is the amount of time for the round-trip between A and B.where is the delay which made by the light traveling and is the angular frequency of optical modulation.Then substitute the values in the equation D=ct/2,D=1/2 ct=1/2 c/=c/(4f) (N+)=c/4f (N+N)=U(N+)in this equation, U stands for the unit length. stands for the delay part which does not fulfill .N stands the decimal value.Discrimination Some instruments are able to determine multiple returns, as above. These instruments use waveform-resolving detectors, which means they detect the amount of light returned over a certain time, usually very short. The waveform from a laser pulse that hits a tree and then the ground would have two peaks. The first peak would be the distance to the tree, and the second would be the distance to the ground.Using wavefront sensing, it is possible to determine both the closest and the farthest object at a given point. This makes it possible for aircraft-mounted instruments to see through dense canopiesclarification needed Please explain how lasers see through canopies and other semi-reflective surface such as the ocean, leading to many applications for airborne instruments such as: 1. Creating bare earth topographic maps - removing all trees 2. Creating vegetation thickness maps 3. Bathymetry(measuring topography under the ocean) 4. Forest firehazard Technologies Time of flight - this measures the time taken for a light pulse to travel to the target and back. With the speed of light known, and an accurate measurement of the time taken, the distance can be calculated. Many pulses are fired sequentially and the average response is most commonly used. This technique requires very accurate sub-nanosecond timing circuitry. Multiple frequency phase-shift - this measures the phase shift of multiple frequencies on reflection then solves some simultaneous equations to give a final measure.Interferometry - the most accurate and most useful technique for measuring changes in distance rather than absolute distances.ApplicationsMilitaryAn American soldier with a GVS-5 laser rangefinder. A Dutch ISAF sniper team displaying their Accuracy International AWSM .338 Lapua Magnum rifle and Leica/Vectronix VECTOR IV laser rangefinder binoculars.Rangefinders provide an exact distance to targets located beyond the distance of point-blank shooting to snipers and artillery. They can also be used for military reconciliation and engineering. Handheld military rangefinders operate at ranges of 2 km up to 25 km and are combined with binoculars or monoculars. When the rangefinder is equipped with a digital magnetic compass (DMC) and inclinometer it is capable of providing magnetic azimuth, inclination, and height (length) of targets. Some rangefinders can also measure a targets speed in relation to the observer. Some rangefinders have cable or wireless interfaces to enable them to transfer their measurement(s) data to other equipment like fire control computers. Some models also offer the possibility to use add-on night vision modules. Most handheld rangefinders use standard or rechargeable batteries. The more powerful models of rangefinders measure distance up to 25 km and are normally installed either on a tripod or directly on a vehicle or gun platform. In the latter case the rangefinder module is integrated with on-board thermal, night vision and daytime observation equipment. The most advanced military rangefinders can be integrated with computers. To make laser rangefinders and laser-guided weapons less useful against military targets, various military arms may have developed laser-absorbing paint for their vehicles. Regardless, some objects dont reflect laser light very well and using a laser rangefinder on them is difficult. 3-D Modelling This LIDAR scanner may be used to scan buildings, rock formations, etc., to produce a 3D model. The LIDAR can aim its laser beam in a wide range: its head rotates horizontally, a mirror flips vertically. The laser beam is used to measure the distance to the first object on its path. Laser rangefinders are used extensively in 3-D object recognition, 3-D object modelling, and a wide variety of computer vision-related fields. This technology constitutes the heart of the so-called time-of-flight 3D scanners. In contrast to the military instruments described above, laser rangefinders offer high-precision scanning abilities, with either single-face or 360-degree scanning modes. A number of algorithms have been developed to merge the range data retrieved from multiple angles of a single object to produce complete 3-D models with as little error as possible. One of the advantages that laser rangefinders offer over other methods of computer vision is that the computer does not need to correlate features from two images to determine depth information as in stereoscopic methods. Laser rangefinders used in computer vision applications often have depth resolutions of tenths of millimeters or less. This can be achieved by using triangulation or refraction measurement techniques as opposed to the time of flight techniques used in LIDAR. Forestry Laser rangefinder TruPulse used for forest inventories (in combination with Field-Map technology) Special laser rangefinders are used in forestry. These devices have anti-leaf filters and work with reflectors. Laser beam reflects only from this reflector and so exact distance measurement is guaranteed. Laser rangefinders with anti-leaf filter are used for example for forest inventories.Sports Laser rangefinders may be effectively used in various sports that require precision distance measurement, such as golf, hunting, and archery. Some of the more popular manufacturers are: Opti-logic Corporation, Bushnell, LaserTechnology, Trimble, Leica, Newcon Optik, Nikon, and Swarovski Optik.Industry production processes An important application is the use of laser Range finder technology during the automation of stock management systems and production processes in steel industry.Safety Laser rangefinders for consumers are laser class 1 devices and therefore are considered eyesafe. Some laser rangefinders for military use exceed the laser class 1 energy levels. History Development of the methods used in modern printed circuit boards started early in the 20th century. In 1903, a German inventor, Albert Hanson, described flat foil conductors laminated to an insulating board, in multiple layers. Thomas Edison experimented with chemical methods of plating conductors onto linen paper in 1904. Arthur Berry in 1913 patented a print-and-etch method in Britain, and in the United States Max Schoop obtained a patent1 to flame-spray metal onto a board through a patterned mask. Charles Durcase in 1927 patented a method of electroplating circuit patterns. The Austrian Jewish engineer Paul Eisler invented the printed circuit while working in England around 1936 as part of a radio set. Around 1943 the USA began to use the technology on a large scale to make proximity fuses for use in World War II . After the war, in 1948, the USA released the invention for commercial use. Printed circuits did not become commonplace in consumer electronics until the mid-1950s, after the Auto-Sembly process was developed by the United States Army. Before printed circuits (and for a while after their invention), point-to-point construction was used. For prototypes, or small production runs, wire wrap or turret board can be more efficient. Predating the printed circuit invention, and similar in spirit, was John Sargroves 19361947 Electronic Circuit Making Equipment (ECME) which sprayed metal onto a Bakelite plastic board. The ECME could produce 3 radios per minute. During World War II, the development of the anti-aircraft proximity fuse required an electronic circuit that could withstand being fired from a gun, and could be produced in quantity. The Centralab Division of Globe Union submitted a proposal which met the requirements: a ceramic plate would be screenprinted with metallic paint for conductors and carbon material for resistors, with ceramic disc capacitors and subminiature vacuum tubes soldered in place. Originally, every electronic component had wire leads, and the PCB had holes drilled for each wire of each component. The components leads were then passed through the holes and soldered to the PCB trace. This method of assembly is called through-hole construction. In 1949, Moe Abramson and Stanislaus F. Danko of the United States Army Signal Corps developed the Auto-Sembly process in which component leads were inserted into a copper foil interconnection pattern and dip soldered. The patent they obtained in 1956 was assigned to the U.S. Army. 4 With the development of board lamination and etching techniques, this concept evolved into the standard printed circuit board fabrication process in use today. Soldering could be done automatically by passing the board over a ripple, or wave, of molten solder in a wave-soldering machine. However, the wires and holes are wasteful since drilling holes is expensive and the protruding wires are merely cut off. In recent years, the use of surface mount parts has gained popularity as the demand for smaller electronics packaging and greater functionality has grown.激光测距仪激光测距仪是一种设备，它采用了激光束来确定对象的距离 。激光测距仪的最常见的形式运行在窄光束激光脉冲通过发送对对象和测量飞行时间原则上要反映小康的目标，并退回给发件人脉冲的时间 。由于高光的速度，这种技术是不为亚毫米级的测量精度高，在适当的三角和其他技术经常被用来。脉冲 编码脉冲可减少测距仪可机会卡住 。 这是可能使用多普勒效应的技术，来判断该对象是否是朝向或远离测距仪，如果这样的速度有多快。 精密 该仪器的精度是由激光脉冲的上升或下降时间和接收器的速度。 一个使用非常尖锐的激光脉冲，并有一个非常快的探测器范围对象几毫米之内。范围 尽管是窄的光束 ，它最终将遍布由于长距离的激光束发散 ，以及由于闪烁和光束漂移的影响，由大小不等，从镜头的空气中存在气泡引起的微观到激光束的路径在地球上空大约有一半的高度。 这些大气中的扭曲与激光本身的分歧，并为推动横向风，再加上大气的热气泡横向相结合，使其很难获得一个物体的距离准确的读数，说下一些树木或灌木丛背后，或什至超过开放，视野开阔的沙漠地形中超过1公里长的距离。 激光有些人可能会反映树叶或树枝，这是比对象更紧密，从而早日回归和阅读太低。 另外，距离超过1200英尺（365米），如果在接近地球的目标，不再只是可能到由温度引起的海市蜃楼 ，在弯曲的激光加热表面附近的空气梯度消失。 所有这些影响必须加以考虑。计算 点A和B之间的距离D=ct/2其中 c是光在大气中的速度和t是为A和B之间的往返时间 哪里 光旅游和延迟 光调制角频率。然后替换值的公式：D = CT / 2，= 1/2克拉= 1/2 C/= C /（4f）（N+）= c/4f（+n）的= （+）在这个公式中，U代表单位长度。 表示延迟部分不履行。 N代表的十进制值。歧视 有些工具是能够确定多回报，如上。这些文书的使用波形 ，解决探测器，这意味着他们检测到的光量，在一定的时间返回，通常很短。 从击中了一棵树，然后在地面的激光脉冲的波形，将有两个高峰。 第一个高峰将树的距离，第二个会到地面的距离。 使用波前探测，这是可能的，以确定最近和最远的物体在某一时间点。 这使得机载仪器看到“通过”密集的遮篷和其他半反射的表面，如海洋，导致许多应用，如空中文书：1.创建“裸露”地球地形图 -消除所有的树木2.创建植被厚度地图3.水深 （下测量地形海洋 ）4.森林火灾的危险技术飞行时间 -测量光脉冲的时间，前往目标和背部。 与已知的光的速度，时间的精确测量，距离可以计算出来。 许多脉冲发射顺序，是最常用的平均响应。这种方法需要非常精确的子纳秒级定时电路。多频相移 -这个测量多个频率上反射相移，然后解决了一些联立方程组，给一个最终的措施。干涉 -测量距离的变化，而不是绝对的距离最准确，最有用的技术。应用军事 测距仪提供了一个空白点位于距离以外的目标拍摄狙击手和炮兵的精确距离。 手持式军用测距仪在2公里至25公里范围内运作，并结合双筒望远镜或单筒望远镜。 当测距仪配备数字磁罗盘（DMC）和倾角，它是能够提供磁方位角，倾角，目标高度（长度）。还有些测距仪可以测量目标的速度，在关系到观察员。 某些测距仪拥有有线或无线接口，使他们以他们的测量（S）数据传输到其他设备，如消防控制计算机。 有些机型还提供了可能性，使用附加的夜视模块。大多数手持测距仪使用标准或可充电电池。 测距仪测量距离可达25公里和更强大的模型通常安装在三脚架上，或直接上车或枪平台。 在后一种情况下的测距模块集成板上热，夜视和白天的观测设备。 可以与计算机集成最先进的军事测距仪。 为了使激光测距仪和激光制导武器打击军事目标，各种军事武器可能已开发的激光吸收其车辆的油漆。 无论如何，某些对象不反映激光非常好，对他们使用激光测距仪是困难的。3-D建模 激光测距仪被广泛使用的3-D物