Measurement System Of Visible Spectrophotometer Based On ARM

Visible Spectrophotometer is used to conduct qualitative material analysis of instrument by using spectrophotometry. It is widely used in clinical medicine, pharmaceutical, toxicology detection, health epidemic prevention, agriculture, industry and some other fields. In China, study on visible spectrophotometer started in the late 1960s, which was later than the occident. By learning the advanced technology of foreign products and independent innovation, the visible spectrophotometer has been industrialized in China. However, the slather of MCU system limited the service performance of instrument. In view of the advantages of high-performance, low power, low-cost, embedded system widely used in the field of modern medical equipment. In order to improve data processing capacity and stability, reduce production cost, increase product functionality and extend the product life cycle, a measurement system of visible spectrophotometer based on ARM is designed in this topic.According to the feature of embedded ARM and visible spectrophotometer, this measurement system is divided into a optical system, a data acquisition module, a microprocessor module, a human-computer interaction module and a communication interface module. The optical system uses prism splitter to obtain the necessary experimental monochromatic. The data acquisition module consists of the silicon photodiode, the MAX406 operational amplifier and a 16-bit A/D converter AD7705 to complete signal photoelectric conversion, amplification and analog-digital conversation. The S3C2410 micro-processing module consists of the core board and its peripheral circuits, achieving overall system controlling, resetting, power supplying and guide program and functions downloading. The human-computer interaction module provides a friendly interface through the LCD, implements parameter inputting and function selection by matrix keyboard and touch screen coordination work, and saves the test results in SD card in order to easily querying and storage. The communication interface module includes the USB interfaces, the serial ports and the network port. And this model connects the USB interface device, serial interface devices, computers and network devices.According to the performance testing experiments of the visible spectrophotometer and the , tests experiments were carried out on indexes of visible, near-infrared spectrophotometers, design of sensitivity, the most error of transmittance, the repeatability of transmittance, T-A shift deviation, absorption curve drawing, standard curve drawing and sample. It showed in the experimental data that the sensitivity, the most error of transmittance and the repeatability of transmittance of the visible spectrophotometer meets the relevant requirements of the JJG178-2007 ultraviolet, visible, near-infrared spectrophotometers measurement verification regulations, T-A shift deviation is small, and the system can complete the absorption curve and standard curve drawing and the samples testing.