Research And Development Of Intelligent Digital Refractometer

The refractive index of transparent, translucent material is an important characteristic parameter. The refractive index measurement is widely applied in the field of food, sugar, oil, chemical industry, environmental protection, and glasses, jewelry appraisal industry. Because of its pure optical and mechanical structure, traditional Abbe refractometer can not meet the requirements of the accuracy and efficiency of current industrial technology. Most of the digital measuring products of refractive index which were introduced to the market often have complex optical structure, with expensive price. The biggest drawback is that they cannot both measure the refractive index of solid and liquid material, which cannot meet the needs of the market. This dissertation takes the industrial automation production as the application background, with high precision and fast automatic measurement purpose, to develop an intelligent digital refractometer based on a linear array CCD image sensor which can both measure the refractive index of solid and liquid material.Based on the principle of total reflection of light, an isosceles trapezoid reflecting prism is used for main tesing prism, a linear array CCD image sensor is applied to detect the terminator position instead of visual observation, and on the basis of measurement range and resolution, analysis and design of the optical system of this instrument is completed. The use of monochromatic source can avoid the impact of the measured material dispersion, while the use of linear array CCD image sensor can improve the instrument measuring accuracy and degree of automation.A high performance microprocessor C8051F060 is used as the core element, the hardware circuit design of the whole machine and the selection of various related devices are completed. The rendering of hardware circuit principle diagram and layout of PCB board are achieved by using Altium Designer and the design of software system of instrument is achieved by the use of C programming language, which includes the control system software and image processing software. The debugging of the hardware and software of the whole machine shows that it can realise each intended function.Testing experiments on the principled sample machine are accomplished. The experimental results show that the overall design of optical system is reasonable, hardware circuit is in accord with the requirements, man-machine interface is convenient to use. It can be used for testing the refractive index of solid materials and liquid materials, which has a useful development and application prospect.