Liquid Refractive Index Based On Cmos Image Sensors

In this paper, the design of a refractive index meter for liquid which was based on image sensor of CMOS was described detailed. The system took the principle of total internal reflection in critical angle when light was propagated from an optically denser medium into one which is optically less dense. Light intensity reflected from the interface of the liquid to be tested and glass could be detected by the image sensor of CMOS. Therefore we could obtain the critical place through the calculation of light intensity distribution curve and converted it to critical angle. Finally, refractive index and brix could be calculated by a set of equations. All data of the experiment system were restored and were calculated in MCU, and displayed in LCD segments. Request for precision and stability of the system were discussed particularly. The achievement of subpixel was investigated. The circuit of experimental system characterized high level of integration and low power consumer, which meet the request for portable application.Software and hardware were described detailed. The system of hardware was composed of LED, CMOS and main control chip. The system of software included the setup of the initialization register of the CMOS image sensor by the simulation of I2C bus using MCU, data acquisition and processing of CMOS image sensor and the following processing and display by MCU.Modification and enhancement of the system was prospected and presented, too.