【正文】 激光 激光與普通光線(xiàn)相比具有能量高度集中，方向性好，頻率單純、相干性好等優(yōu)點(diǎn)，是很理想的光源。此外，光電開(kāi)關(guān)的結(jié)構(gòu)元件中還有發(fā)射板和光導(dǎo)纖維，三角反射板是結(jié)構(gòu)牢固的發(fā)射裝置。溫度特性 光敏電阻受溫度影響甚大，溫度上升，暗電流增大，靈敏度下降，這也是光敏電阻的另一缺點(diǎn)。圖5光敏電阻的伏安特性光電特性 光敏電阻兩極間電壓固定不變時(shí)，光照度與亮電流間的關(guān)系稱(chēng)為光電特性。在輸出電流小于1mA的情況下，它的光電特性在很寬的范圍內(nèi)具有良好的線(xiàn)性關(guān)系。在圖2所示的電路中，電流和電阻只上的電壓降就和光強(qiáng)成函數(shù)關(guān)系，從而實(shí)現(xiàn)光電轉(zhuǎn)換。光強(qiáng)度愈強(qiáng)，其阻值愈小，若停止光照，其阻值恢復(fù)到原阻值。 由上式可知，要使光電子逸出陰極表面的必要條件是hA。s also a vulnerable to external disturbance and lose the measurement accuracy of the device. When be being designed so besides the choice optoelectronic ponents, still must set GSCC signal and temperature pensating measures used to weaken or eliminate the impact of these factors. Photoelectric sensor must pass a light modulation, like radio waves of light modulation of sends and receives, the radio to a station, can ignore other radio signal sensors without modulation longfocallength only through the use of mechanical shielded, scenes that receiver transmitter only can receive the emission of light, can make its energy bees very high. In contrast, through modulation transceivers can ignore ambient light, only to own light or with the same modulation frequencies of light without modulation response. The sensor used to test the infrared rays or around the radiation, if just baked red bottle, in this application situation if use other sensor, may be incorrect actions. Photoelectric sensor due to noncontact, high reliability, etc, and to change in measurement, damage the object to be tested So since its invention in fields since play a significant role, at present it has been widely used in measuring mechanical quantity, thermal quantity, weight, intelligent vehicle system into etc. Now it in power system automatically grid device plays a very important role, because generator input power grid operation often USES accurate with law, must meet: threephase line sequence is consistent, frequency, phase agree unanimously, voltage amplitude equal, one of the conditions in system design has been satisfied, after three conditions must also meet to grid, of course, artificially grid is more difficult, photoelectric grid is easier. The development of times, science and technology in the update, photoelectric sensor types are increasing and application domain more and more widely, such as a recent kind of infrared already in intelligent vehicle electrical sensors in to the application, one of which had based on infrared sensor is the core of intelligent vehicle, reflective type infrared sensor using reflex infrared sensor design path detection module and speed monitoring module。t produce photoelectron launch, this frequency limit called red limit. The corresponding wavelength for type, c for the speed of light, A reactive for escaping. When is the sun, its electronic energy, absorb the resistivity reduce conductive phenomenon called optical effects. It belongs to the photoelectric effect within. When light is, if in semiconductor electronic energy big with semiconductor of forbidden band width, the electronic energy from the valence band jump into the conduction band, form, and at the same time, the valence band electronic left the corresponding cavities. Electronics, cavitation remained in semiconductor, and participate in electric conductive outside formed under the current role. In addition to metal outer, most insulators and semiconductor have photoelectric effect, particularly remarkable, semiconductor optical effect according to the optoelectronics manufacturing incident light inherent frequency, when light resistance in light, its conductivity increases, resistance drops. The light intensity is strong, its value, if the smaller, its resistance to stop light back to the original value. Semiconductor produced by light illuminate the phenomenon is called light emf, born volts effect on the effect of photoelectric devices have made sibased ones, photoelectric diode, control thyristor and optical couplers, etc. Second, optoelectronic ponents and characteristics According to the outside optoelectronics manufacturing optoelectronic devices have photoelectron, inflatable phototubes and photoelectric times once tube. 1. Phototubes phototubes are various and typical products are vacuum phototubes and inflatable phototubes, light its appearance and structure as shown in figure 1 shows, made of cylindrical metal half cathodic K and is located in the wires cathodic axis of anode in A package of smoke into the vacuum, when incident light within glass shell in the cathode, illuminate A single photon took all of its energy transfer to the cathode materials A free electrons, so as to make the freedom electronic energy increase h. When electrons gain energy more than escape of cathode materials, it reactive A metal surface constraints can overe escape, form electron emission. This kind of electronic called optoelectronics, optoelectronic escaping the metal surface for after initial kinetic energy Phototubes normal work, anode potential than the cathode, shown in figure 2. In one shot more than red light frequency is premise, escape from the optoelectronic cathode surface by positive potential attracted the anode in photoelectric tube forming space, called the current stream. Then if light intensity increases, the number of photons bombarded the cathode multiplied, unit of time to launch photoelectron number are also increasing, photocurrent greatens. In figure 2 shows circuit, current and resistance is the voltage drop across the only a function of light intensity relations, so as to achieve a photoelectric conversion. When the LTT optoelectronic cathode K, electronic escape from the cathode surface, and was the photoelectric anode is an electric current, power plants absorb deoxidization device in the load resistance I, the voltage Phototubes photoelectric characteristics shows, from the graph in flux knowable, not too big, photoelectric basic characteristics is a straight line. 2. Photoelectric times had the sensitivity of vacuum tube due to