1、它也可以通过光的传输,阻隔,反射,干扰来测量各种物理量,如物体的大小,位移,速度,温度等。所以它是一个具有广泛应用前景的至关重要的灵敏器件。当使用光电式传感器时,光电式传感器不直接与被测物体接触,光束质量几乎为零,在测量过程中不存在摩擦力,且在被测物体上几乎没有任何压力。因此,光电传感器在很多应用方面都比其他传感器具有明显的优势。然而,它的缺点是在某些应用场合中光学器件和电子设备是比较昂贵的,而且在测量过程中对环境条件的要求较高。近年来,新型光电子器件的不断涌现为光电式传感器的进一步应用开创了新的一页尤其是CCD图像传感器的出现。2 光电传感器的原理光电传感器是以光电器件作为转换元件的传感器。
2、该光电传感器的原理是把被测量的变化转换成光信号的变化,然后借助光电元件进一步将光信号转换成电信号的光电组件。光电传感器一般由光源、光学通路和光电元件三部分组成。光电传感器的工作过程如图1所示。图1 光电式传感器的工作过程光电器件的作用是将光信号转换成基于光电效应的电信号。光电效应是一种物理现象,光照射到某些物质,并导致物体电性质发生重大改变。它可分为外光电效应和内光电效应。外光电效应是物体内的电子在光的作用下逸出物体表面的物理现象。光子是量子“粒子”来描述可见光波的形式。光子的能量为hv,h是普朗克常数,v是光的频率。光子通量的光强度相对应。 Einstein方程所描述的外部光电效应:hv=1
3、/2*mv02其中m是电子质量,V0是电子逃逸速度。当光子的能量等于或大于功函数时,就会产生外光电效应。因此,每个对象都有一个相应的光电临界频率,被称为红色极限频率。如果它超过了入射光频率的红色极限频率,那么外源的光电流与光强度成比例。当光照射到物体上,它可以导致电导率发生改变或产生光生电动势,这就是所谓的内部光电效应。内部光电效应分为光生伏特效应和光电导效应。光伏效应的作用是使对象在光的影响下具有一定力的方向。在该作用下的光电子器件是光敏二极管,晶体管,太阳能电池;光电效应是在光线的作用下,电子吸收光子的能量从粘合状态过渡到自由状态,从而导致材料电导率的变化。光敏电阻器等器件就是基于这样的效
4、果的光电子器件。3 光电式传感器的分类光电传感器的分类是多种多样的。光电传感装置根据外光电效应分为光电管和光电倍增管。根据光电导效应制成了光敏电阻。根据光电传感器的阻隔效果分为光电二极管和光电晶体管。根据光电效应的相反过程制成了反向光电二极管。光电式感应器根据信号的形式可以分为模拟光学传感器和数字光学传感器。光电式传感器还包括光纤传感器,固态图像传感器等。图2所示为常见的光电传感器。图2 常见的光电传感器4 光电传感器的应用随着技术的发展,光电式传感器使用越来越多。光电传感器在日常生活,工业生产和信息技术中的应用越来越多。4.1 光源是被测物体的应用光照度E的单位为勒克斯(lux),这是光度学
5、中常用的单位之一,这意味着照明系统的物理对象的曝光程度,它可以被用来测量照度计。1)红外辐射温度计红外辐射温度计经常应用于非接触式温度测量。红外辐射温度计即可用于为高温度测量也可用于低于冰点的低温度测量,这也是辐射温度计的趋势。市售红外测温仪温度范围从-303000,中间被分成几个不同的规格,你可以根据需要选择合适的型号。图3所示为红外辐射温度计的形状。图3 红外辐射温度计的形状2)热电型红外线传感器热电型红外线传感器可以检测到人或动物发送的红外光并输出相应的电信号。热电型红外线检测装置已被广泛用于红外光谱法,红外遥感和辐射探测器中。它也可用于能产生远红外辐射的人体检测和报警中。如防盗门,酒店
6、大堂的自动门,自动灯光控制。例如:当没有人在房间里时,它会自动关闭空调,饮水机;电视可以判断当没有人在看或有人睡眠时自动关闭电路。图4所示为热电型红外线传感器的形状。图4 热电型红外线传感器的形状4.2 被测物体吸收光能的应用在此应用中,被测物体可以吸收光能,根据目标的光能量的减弱程度来实现目标的分析和测量。1)光电浊度仪光电浊度仪是基于传输衰减和红外光散射的衰减与悬浮泥沙浓度密切相关的原则来实现污泥的浓度和悬浮物测量。不同类型的污泥和悬浮物有不同的红外光的衰减,我们可以调整发送频率,并使用不同的算法,以满足不同的应用。2)烟雾报警器没有烟雾时,光敏元件能接收到一个恒定的红外信号。一旦发生火灾
7、,烟雾进入房间,并阻止一些红外光,光电晶体管输出信号被削弱,这是判断的阈值电路,发出报警信号。图5所示为烟雾报警器。图5 烟雾报警器4.3 被测物体反射光通量的应用该传感器采用漫反射的原理。在这种传感器中,发射器和接收器安装在同一设备上。由发射器发射的光被目标对象所反射,并充满了各个方向,反射光的一部分反射到接收器,所以可以检测出目标对象。1)反射式光烟报警器在没有烟雾的情况下,由于红外管垂直于内部涂满了黑色的烟雾吸收材料,所以红外光无法到达红外光敏晶体管。当烟雾进入烟室,烟产生的固体颗粒对红外光的漫反射,使部分的红外光到达红外光敏晶体管并输出光电流。2)光电式转速表光电式转速表是反射的光电式
8、传感器,它可以从与被测物体外部相差几十毫米的地方无接触的测量速度。3)颜色传感器色彩传感器被用于检测一个特定的颜色或对象的位置,它测量颜色时通过与没有颜色的区域进行比较,而不是直接测量。4.4 被测物体遮光的应用遮光式光电传感器需要两个独立的条件,发光装置安装在一个机箱内,接收机安装在另一个机箱。发射出来的光从发射装置注入到接收装置,当目标对象遮挡了光的传播,接收器的输出将会改变。带钢偏差的光电检测器。当带钢偏移正确的位置时,边缘往往与发送机碰撞,造成钢材的浪费。当带材处于正确的位置(中间位置)时,放大器的输出电压为零,当带材进入左侧,遮光面积减小,输出电压反映条形的方向和大小的偏差。带钢偏差
9、的光电检测器,如图6所示。图6 带钢偏差的光电检测器5 光电式传感器的发展随着半导体技术在60年代的迅速发展,光敏半导体器件发展迅猛。在此期间,各种光学材料已被充分研究和广泛使用。人们通过对光电效应及其设备的研究已经开发出多种适合不同场合的光电器件。再加上由于薄膜技术,表面处理技术和大规模集成电路技术的发展,光电式传感器的制造过程也达到了一个较高的水平,大大降低了产品成本。在过去的几十年中,红外传感器和其他光学传感设备在航空航天和国防领域获得了广泛的应用。在未来几年中,主要的传感器技术将在灵敏度,分辨率和整体性能上实现突破。光电式传感器的应用已经扩展到纺织业,造纸业,印刷,医疗,环保。传统领域
10、的研究有了新的发展,如红外探测,辐射测量,光纤通信,自动控制等。红外传感器和微光传感器是使用最广泛的光电式传感器。红外传感器分辨率的增加,且对制冷的需求降低提高了其可靠性。微光传感器依赖于传统的图像增强器的提高以及传感器的模拟信号转换为数字信号。这两种技术的发展趋势是各种多光谱传感器技术的整合,这可以最大限度地发挥个人技术的表现,越来越多的应用到手持设备和无人驾驶汽车等领域。结合几种不同的光电传感器的长处会发现有很多的优点,但只有它被用来在适当的场合时才可以发挥这些优势。例如,微光传感器更适合在夜间观察大面积,但不足以检测静态隐藏在树林里的人。在这种情况下,如果我们用长波红外相机融合微光传感器
11、,那么隐藏在树林里的人将是可见的。如果我们用另一种短波红外传感器与之融合,那么我们甚至可以识别隐藏在树林里的人的面部特征。此外,在光电式传感器的另一个主要趋势是增加像素焦平面阵列的数目。原文:The Application and Development of PhotoelectricAbstract: At present, the application of photoelectric sensors are more and more extensive, it also promotes the development of photoelectric sensors. Photo
12、electric sensor has simple structure and diversity. It has high precision, fast response, non-contact and other advantages. In this paper, we analyze the principle of photoelectric sensors, introduce the classification of photoelectric, and then highlight introduce the application of photoelectric s
13、ensors and the use of the principle of photoelectric sensors, analyze the current and future development of photoelectric sensors.Keywords: Photoelectric sensor, the application of photoelectric sensor, the development of photoelectric sensor.1 IntroductionPhotoelectric sensor is the sensor to use t
14、he electronic and optical element as the detection component. Photoelectric detection has high precision, fast response, noncontact advantages and so on. The sensor has simple structure, flexible and diverse forms. Therefore, the photoelectric sensor is widely used in the field of control and testin
15、g. It can be used to detect the non-electricity which can cause changes in the amount of light, such as light intensity, radiation temperature, gas composition. It can also use light transmission, occlusion, reflection, interference and others to measure a variety of physical quantities, such as obj
16、ect size, displacement, velocity, temperature, etc. So it is an important and sensitive device which has a very wide application. When using the photoelectric sensor, it doesnt directly contact with the measured object and the beam quality is nearly zero, there is no friction in the measurement and
17、almost no pressure on the measured object. Therefore, photoelectric sensors has obvious advantages than other sensors in many applications. However, its drawback is that optical devices and electronic devices are more expensive in some applications, and environmental conditions require higher on the
18、 measurement. In recent years, new optoelectronic devices are been emerging, particularly the birth of CCD image sensor, that creates a new field for the further application of photoelectric sensors.2 The Principle of Photoelectric SensorPhotoelectric sensors use photoelectric elements as sensor con
19、version devices. The principle of photoelectric sensor is to reflect the measured objects changes by light signal, and then convert the light signal into electrical signals by optoelectronic components. Usually the photoelectric sensor is composed by light source, optical access and optical componen
20、ts. The working process of photoelectric sensor is shown in Figure 1.Fig. 1. The working process of photoelectric sensorThe role of optoelectronic devices is to convert the optical signal into electrical signal, which is based on the photoelectric effect. Photoelectric effect is a physical phenomeno
21、n that the light shines on certain substances and causes the material to change in the electrical characteristics. It can be divided into external and internal photoelectric effect.External photoelectric effect is the physical phenomena that the objects electron escape surface of the object and emit
22、s outside under the influence of light. Photon is in the form of quantum particles to describe visible light waves. Photon energy is hv, h is the Planck constant, v is the optical frequency. Photon flux corresponds to light intensity. External photoelectric effect is described by the Einstein equati
23、on:Where m is electron quality, v0 is electronic escape velocity. When the photon energy is equal to or greater than the work function, the external photoelectric effect can be generated. So each object has a corresponding effect on the photoelectric threshold frequency of light, known as the red li
24、mit of frequency. For more than the red limit of the incident light frequency, exogenous photocurrent is proportional to light intensity.When light shines on the object, it can cause the resistivity to change or generate photo-emf which is called the internal photoelectric effect. The internal photo
25、electric effect is divided into photovoltaic effect and photoconductivity effect. Photovoltaic effect is the phenomenon that makes objects have a certain direction of the force under the influence of light. Optoelectronic devices based on the effects are photosensitive diodes, transistors, photovolt
26、aic cells; photoconductive effect is that under the influence of light, electrons absorb the photon energy from the bonding state of transition to a free state, which leads to material changes in conductivity. Optoelectronic devices based on this effects are photosensitive resistor and so on.3 The C
27、lassification of Photoelectric SensorPhotoelectric sensor classification is varied. Photoelectric sensing devices based on external photoelectric effect are photoelectric tubes and photomultiplier tubes. Photoelectric sensors based on photoconductive effects are photoresistors. Photoelectric sensors
28、 based on barrier effects are based on photodiodes and phototransistors. Photoelectric sensors based on reverse side of the photoelectric effect are reverse photodiodes. Photoelectric sensors can be classified into analog optical sensors and digital optical sensors by signal forms. Photoelectric sen
29、sors also include fiber optic sensors, solid image sensors and so on. Figure 2 shows common photoelectric sensors.Fig. 2. Common photoelectric sensors4 The Application of Photoelectric SensorWith the development of technology, the use of photoelectric sensors is more and more. Photoelectric sensors
30、have a growing number of applications in everyday life, industrial production and information technology.4.1 The Application that Light Source Is the Measured ObjectThe unit of light illumination E is lx (lux), which is one of the units commonly used in photometry, it means the degree of exposure of
31、 the illuminated physical object, it can be used to measure the illuminance meter.1)The infrared radiation thermometerInfrared radiation thermometer has many applications in non-contact temperature measurement. Infrared radiation thermometer can be used for both high temperature measurement and below freezing temperature measurement, this is also the trend of radiation thermometer. Commercially available infrared thermometer temperature is
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