Design Of Optical Power Meter Based On PIN Photodilde

Optical power meter is an instrument that detected the light signal power, it iscommonly used in optical test equipment, widely used in optical fibercommunication, biomedical and other high-tech fields. At present, the domesticdevelopment of optical power meter used in photoelectric detector photomultipliertubes and photocells, the disadvantage of the photomultiplier tube for thephotodetector optical power meter is high operting voltage and affected by theenvironment. However the power meter using photovoltaic cells due to the influenceof the dark current, the error is larger. Obviously, optical power meter exist obviousshortcomings for field engineering. In rencent years, with research and developmentof the new photodetector, such as PIN photodiode in optical signal detection, notonly the detection accuracy is better than photovoltaic cells, and lessaffected by thework environment factors. In this paper, the PIN photodiode as a photodetector,designed a power meter for field engineering applications.To obtain accurate optical power value, need to obtain the spectral responsivityof the PIN photodiode and the photocurrent value. In this paper, the carrier continuityepuation in the basic equations of semiconductor analysis and calculation of thephotoelectric conversion process of the PIN photodiode, deduced function of thespectral responsivity of the photodiode on the wavelength of incident light. Thephotocurrent of the PIN photodiode I/V conversion, to convert the voltage value, bymeasuring the voltage value to abtain the value of the photocurrent of the PINphotodiode.In the design of the optical power meter, first, using a logarithmic amplifier I/Vconversion and amplification; Second, in order to meet the requirements of thefollow-up A/D conversion accuracy, design the corresponding voltage signalconditioning circuits; Finally, consider the cost from the power meter, usingcost-effective STC12C5A60S2series microcontroller as the core device, built hardware systems, and completed the preparation of the software. Experimentalresults shows that the light power meter is low cost, fine sensitivity, stableperformance, easy to carry, and basically meet the requirements of the fieldengineering applications.