Based On The Wavelength Of The Photodetector In Silicon Double Junction Color Sensor Measurement

The wavelength measurement system based on dual-junction silicon color sensor is characterized by simple structure, low cost, high precision, and portability, so it has been widely used in optical communication and other industrial fields. But the traditional system is easily influenced by environment, hence the scope of its application is greatly limited. Therefore, it is an urgent task to improve the traditional system to eliminate environmental influence.Through the analysis of the traditional wavelength measurement method based on dual-junction silicon color sensor and the environmental influence on such a system, an environmental compensation wavelength measurement method was proposed based on the dual-junction silicon color sensor. Herewith, an improved system was studied, including the hardware and software being designed and tested in detail.The hardware of the system consisted of the modules of micro-controller, photocurrent acquisition and conditioning, temperature sampling, LCD display, RS-232 serial communication, and power supply. The core of the micro-controller module was ADuC814. The photocurrent acquisition and conditioning module included circuits of photocurrent sampling, current-to-voltage conversion, and signal processing. The temperature sampling module employed DS18B20 to acquire the temperature signal. The LCD module was used to display the measurement result on the SMS0401. The RS-232 serial communication module used MAX232 to implement electric level matching. The outputs of the power supply were ±5V and +4.096V.The system software was comprised by the lower- and upper-end computer programs. For the lower-end micro-computer programs, the photocurrent and temperature were sampled, then the acquired data would be processed by the lower-end controller directly in the off-line mode, or transferred to the upper-end computer in the on-line mode. In the off-line mode, the measured wavelength value would be displayed on the LCD. In the on-line mode, the upper-end computer programs would analyze and process the data from the lower-end and then get thewavelength or calibration parameters. In addition, depending on the user's requirement, the calibration coefficients could be downloaded from the upper-end to the lower-end computer.Based on the desined system, two comparative experiments were carried out. One experiment was performed to compare the measurement accuracy between the improved and traditional methods under the influence of environmental temperature. The other was used to compare the performance of these two methods under the influence of the ambient light. These experiments not only indicated that the improved method was much more accurate than the traditional one under the arbitrary environment, but also proved that the improved method effectively reduced the influence of the environmental temperature and the ambient light on the wavelength measurement. Finally, the aspects of this study were summarized, and the possible improvements in this scheme were proposed.