【正文】 測(cè)量電路能夠把光電效應(yīng)造成的光電元件電性能的變化轉(zhuǎn)換成所需要的電壓或電流。 絲燈泡 這是一種最常用的光源，它具有豐富的紅外線。它可以在與光軸0到25的范圍改變發(fā)射角，使光束幾乎是從一根發(fā)射線，經(jīng)過反射后，還是從這根反射線返回。在接收器的前面，裝有光學(xué)元件如透鏡和光圈等。利用內(nèi)光電效率原理制造的光電元件的頻率特性最差，這是由于俘獲載流子和釋放電荷都需要一定時(shí)間的緣故。同樣，在停止光照后，光電流也需要經(jīng)過一段時(shí)間（下降時(shí)間）才能恢復(fù)到其暗電流值，這就是光敏電阻的時(shí)延特性。光譜特性 入射光波長(zhǎng)不同時(shí)，光敏電阻的靈敏度也不同。伏安特性 光敏電阻兩端所加的電壓和流過光敏電阻的電流間的關(guān)系稱為伏安特性，如圖5所示。 光敏電阻 光敏電阻的工作原理是基于內(nèi)光電效應(yīng)。當(dāng)入射光照射陰極K時(shí)，從陰極逸出的光電子被第一倍增電極D1加速，以高速轟擊D1 ，引起二次電子發(fā)射，一個(gè)入射的光電子可以產(chǎn)生多個(gè)二次電子， D1發(fā)射出的二次電子又被DD2問的電場(chǎng)加速，射向D2并再次產(chǎn)生二次電子發(fā)射……，這樣逐級(jí)產(chǎn)生的二次電子發(fā)射，使電子數(shù)量迅速增加，這些電子最后到達(dá)陽極，形成較大的陽極電流。圖3光電管的光電特性圖2光電管測(cè)量電路圖1光電光結(jié)構(gòu)示意圖 由于真空光電管的靈敏度低，因此人們研制了具有放大光電流能力的光電倍增管。在人射光頻率大于“紅限”的前提下，從陰極表面逸出的光電子被具有正電位的陽極所吸引，在光電管內(nèi)形成空間電子流，稱為光電流。 二、光電元件及特性 根據(jù)外光電元件制造的光電元件有光電子，充氣光電管和光電倍曾管。電子、空穴仍留在半導(dǎo)體內(nèi)，并參與導(dǎo)電在外電場(chǎng)作用下形成的電流。相應(yīng)的波長(zhǎng)為 式中，c為光速，A為逸出功。假設(shè)光子的全部能量交給光子，電子能量將會(huì)增加，增加的能量一部分用于克服正離子的束縛，另一部分轉(zhuǎn)換成電子能量。 由于微電子技術(shù)，光電半導(dǎo)體技術(shù)，光導(dǎo)纖維技術(shù)以及光柵技術(shù)的發(fā)展，使得光電傳感器的應(yīng)用與日俱增。 Once the light path be test object to block, accept light, the light is not receive photoelectric switch is action, output a switch control signals. 4, diffusion reflective photoelectric switches its detection head with a lighter and also an inbox light ware, but no reflex ahead. Normally lighter for the light collect light is not found. When test object by blocking the light, and the light reflected light, receive part implement received light signals, output a switch signals. Four, I39。s sake. Three, photoelectric sensors Photoelectric sensor is through the light intensity changes into electrical signal changes to achieve control, its basic structure, it first figure 6 by measuring the change of change of converting the light signal, and then using photoelectric element further will light signals into electrical signal by photoelectric sensor general. Illuminant, optical path and optoelectronics. Three ponents of photoelectric detection method has high precision, fast response, noncontact wait for an advantage, but measurable parameters of simple structure, sensors, form flexible, therefore, photoelectric sensor in the test and control is widely used. By photoelectric sensor generally is posed of three parts, they are divided into: transmitter and receiver and detection circuit shown, as shown in figure 7, transmitter aimed at the target launch beam, the launch of the beam from semiconductor illuminant, general light emitting diode (LED), laser diode and infrared emission diode. Beam uninterrupted launch, or change the pulse width. Receivers have photoelectric diode, photoelectric triode, posed sibased ones. In front of the receiver, equipped with optical ponents such as lens and aperture, etc. In its back is detection circuit, it can filter out effective signal and the application of the signal. In addition, the structural ponents in photoelectric switch and launch plate and optical fiber, triangle reflex plate is solid structure launch device. It consists of small triangle cone of reflective materials, can make a beam accurately reflected back from plate, with practical significance. It can be in with the scope of optical axis 0 to 25, make beams change launch Angle from a root almost after launch line, passes reflection or from the rotating basic returns. 圖7Photoelectric sensor is a kind of depend on is analyte and optoelectronics and light source, to achieve the relationship between the measured purpose, so the light source photoelectric sensor plays a very important role, photoelectric sensor power if a constant source, power is very important for design, the stability of the stability of power directly affect the accuracy of measurement, monly used illuminant have the following kinds: 1, leds is a change electric energy into light energy semiconductor devices. It has small volume, low power consumption, long life, fast response, the advantages of high mechanical strength, and can match and integrated circuits. Therefore, widely used in puter, instruments and automatic control equipment. 2, silk light bulb that is one of the most monly used illuminant, it has rich infrared light. If chosen optoelectronics, constitutes of infrared sensor sensitive colour filter can be added to the visible tungsten lamps, but only filter with its infrared does illuminant, such, which can effectively prevent other light interference. 3, pared with ordinary light laser laser with energy concentration, directional good, frequency pure, coherence as well as good, is very ideal light sources. The light source, optical path and photoelectric device position photoelectric sensor used in photoelectric detection, still must be equipped with appropriate measurement circuit. The photoelectric effect to the measurement circuit of photoelectric element of widerange caused changes needed to convert the voltage or current. Different photoelectric element, the measurement circuit required is not identical also. Several semiconductor introduces below optoelectronic devices monly used measurement circuit. Semiconductor photoconductive resistance can through large current, be in so usually, need not equipped with amplifier. In the output power of demand is bigger, can use figure 8 shows circuit. Figure 9 (a) with temperature pensation given the photosensitive diode bridge type measuring circuit. When the incident light intensity slow change, the reverse resistance photosensitive diode is the slow change, the change of the temperature will cause the bridge output voltage, must pensate. Drift Picture a photosensitive diode as the test ponents, another into Windows, in neighboring bridge, the change of the temperature in the arms of the influence of two photosensitive diode, therefore, can eliminate the same output with temperature bridge road drift. Light activated triode incident light in work under low illumination, or hope to get bigger output power, also can match with amplifying circuit, as shown in figure 9 shows. Because even in the glare photosensitive batteries, maximum output voltage also only V, still cannot ma