The Design Of Linear CCD Pectrometer System

Since forty years ago CCD was invented, it’s application value is growing day by day. It has already deep into the realm of traditional cameras, optical spectrum analyzer and aerospace detection. Spectrometer is one of instrument which is used to analyze and study the intensity, frequency and other characteristics of light. With the development of the computer technology, the miniaturization, automatic, fast detection, low cost of small spectrometer has achieved more and more applications in social production, scientific experiments, biomedical, environmental monitoring and other fields.In recent years, lots of work has been done to develop spectrometer. However, homemade has a big gap as compared with foreign spectrometer. Such as poor SNR, low accuracy, large size, high costs. Especially in the application of precision measurement, where it need a high precision of synchronous delay, nearly at ns level. If the accuracy is not high enough, it will lead measurements to inaccurate, and an inaccurate data result. Those problems have restricted its application in precise measurement of scientific fields. In order to get a high perfermence and small size, two type of controller has been applicated in this design, one of it is FPGA, and another is STM32.Because of the FPGA’s parallel processing, it can realize high accuracy delay and fast data processing. Through USB2.0, it can achieve real-time display. However, compared with STM32, the disadvantage is it need more peripheral chips, bigger size and more expensive.STM32integrated ADC, USB, timers and other modules. It can realize miniaturization and low cost design. However, due to its restrict of serial processing and slow core driving clock, the accuracy of control is not high enough.Driver circuit is the key point in CCD spectrometer system design, and is the most difficult part. After the results of CCD pixel’s electrical signal processed by the front-end board, it arrived at the main control board, then the ADC convert it into digital signals. Considered a common use, the design mainly uses USB2.0as the data upload interface. The control interface was developed under the environment of Visual Studio2010, using C and C++language. It’s function is receiving and processing data from CCD spectrometer. Through the test, CCD spectrometer system achieves the desired goal, and even many performance is ahead of other similar products.The main work of this paper are as follows: 1. Completed the design of linear CCD system’s driver circuit based on FPGA and STM32.2. Design the logic of FPGA and the programming of STM32.3. Completed the design of data acquisition software on PC.