The Measuring System Of Light Intensity Distribution Of Linear CCD Based On FPGA

With the continuous improvement of CCD’s performance, the measuring systemwith fast sampling, storage, processing and transmission has become the new trend ofthe development of CCD’s data acquisition. Its application range is very wide, involvedin aerospace, broadcast video, industrial vision, measurement, and many other fields.Linear CCD has high sensitivity, wide spectral response, large measuring range, as wellas good linearity. So it shows unique advantages in the field of one dimensional scalemeasurement.In order to improve the precision and integration of the CCD’s non-contactmeasurement system of one dimension, this paper designs a system with the FPGA.Laboratory original measurement system was based on CPLD and MCU, themeasurement system circuit was complex. The powerful FPGA can replace them. Thesystem uses CCD to convert the light signal into analog signals, and then converts intodigital signals through the AD converter. The digital signals store in the FIFOembedded in the FPGA. Finally they display on the upper computer via a serial port. Ituses Verilog HDL language to compile the CCD driver work timing, AD writing timingand FIFO control timing. Then simulate them on the Quartus II software.This article chooses Toshiba TCD1209D. It has a large dynamic range, small darksignal voltage, high total transmission and efficiency. It is very suitable for onedimension measurement. It chooses AD9945for the AD converter, because it is acomplete analog signal processor for the CCD application.In this paper, the noise suppression has carried on the special processing. Powersupply noise is filtered through the LC-π low-pass filter. CCD noise is filtered throughthe low pass filter and the correlated double sampling process. At the same time, wealso need to consider the noise suppression during the layout of the circuit board. Wealso have the signal processing on the PC software, which using the Fourier transform.After the success of the circuit debugging, we need to test the performance andprecision of the system. Specific data and error analysis are given in this paper, and weput forward the improvement methods. The experiment shows that this system is stable,and the precision reaches0.71%. The basic purpose of this system is reached.