Laser Diode Power Monitoring System

Photoelectric detection equipments are enormously demanded in the field of national defense and civil use. The laser is the vital component of the photoelectric detection equipment.The stability of its optical output power is mostly related with the stability and precision of the photoelectric detection equipment. Meanwhile, the stability of the optical output power is the key factor of the performance of the photoelectric detection equipment. Therefore, recording the data of optical output power and analyzing the change of the data will make the debugging and calibration of the photoelectric detection equipment which is installed with the laser more effective and it will provide the important reference of improving the performance of the photoelectric detection equipment.This thesis discusses how to construct a real-time monitoring laser optical output power system which recording the power value. Users can real-timely check the value of the laser optical power and analyze the change regulation of the data via the system. The system is comprised of photoelectric diode acquisition circuit, amplification circuit and Single Chip Micro-Computer-System. The system with the powerful capacity of anti-interference and noise reduction can monitor the trend of the laser optical power round the clock and record the value. The data is transferred via the serial port and convenient for users to inquire.The issue describes photodiode’s circuit in which receives signal in detail, and disscuss the optimization, promotion and capacity of resisting disturbance about this circuit.The content of this issue isthe follow-up processing of the signal which contains passing AD conversion electric circuit, convert light signal and output to singlechip.The singlechip saves date in FLASH to provide user to search.It also can show data on OLED. And the computer can receive the data transported from singlechip by serial port, it saves these data in PC for searching and inquiring.Beside, the issue discusses the way to do simplified calibration of the system in order to make sure that system can work normal.The system can monitor the signal all 24 hours, also can search,record and watch the value of power in the PC, wave-length of light is 780 nm, measurement accuracy is 0.01 dBm, measure scope is-20~10 dBm.The test discovers that the power of laser diode will change with time.Because the performance of laser diode will be affected by temperature, temperature of laser diode will increase with time passed.Because of conversation of energy, more and more energy converts to thermal energy, less energy converts to optical power.