The Design Of Measuring And Controlling System Of The NIRS Instrument Based On CCD

Title: The measuring and controlling system's design of the NIRS instrument based on CCDThe Near-Infrared spectroscopy technique is the most advanced and attractive spectrum analytical technique since 1990's, praised as analytical giant. Because Near-Infrared technique has many advantages such as high analyze speed, low cost and no-pollution, it has been used more and more widely. Near-infrared spectroscopy (NIRS) analysis technology is a physics method to analyze the matter's chemistry composition and content by its emission or absorption spectra reflecting its atoms'and molecules'characters. This analysis technology is mainly used for the qualitative and quantificational analysis for the organic matter, especially those containing the hydrogen-containing functional group. Near-infrared spectroscopy analysis technique refers to the spectroscopy, chemometrics, computer application and basic measuring technique and so on, and it completes the design for optic-mechanical-electric integration.Charge-coupling-chip has a short name of CCD.Making the charge as signal is their great characteristic, rather than it seems like others make the voltage or current as signal.CCD is a kind of photoelectricity-changed chip.It stores and transfers information as a format of charge package.Mainly it is made of photosensitive cell,input structure and output structure etc.The working process of CCD include creat,storage,transfer and readout four courses.This paper totally includes six chapters. The contents of the paper are that I design and complete the measuring and controlling system of the NIRS instrument based on CCD.I complete testing the optical signal,transferring the charge-signal of CCD, processing the analog signals,changing the digital signal with the analog signals,storing the signal,transferring the datas,managing the power supply and design the software.On the base of many study work, the thesis mainly completes the work and result as follows:1. Designed the measuring and controlling system's design of the NIRS instrument based on CCD and complete these functional targets:(1).having achieved transferring the CCD signal truly,amplying the siganal,gaining and transferring the datas quickly;(2).having managed the power supply, reduced the groud-noise in a degree;(3).having completed the controlling and communicating with PC by using MCU.(4).having finished that PC controls and communicates with the bottom by using software.And it can display and compute the spectrum datas. Also the software includes rectifying and demarcating the instrument.2.Debuged the whole instrument, tested the main targets of the instrument,considered that these can meet our request,as follows:(1). the wavelength extension of the instrument can be 700nm～1000nm at least;(2). the mixed and dispersed light reach±0.5%;(3). the wavelength precision is among±0.5nm;(4). the resolving power is less than 10nm;(5). the measurement time is less than 5 seconds;(6). the datas'resolving power is less than 0.5nm;(7). the interval of wacelength can complete lots of choice.In the course of designing the system, i reached some key technique as follow:(1).Use CPLD achieve the clock of CCD,A/D and FIFO's reading by means of figure-programmed and VHDL language;(2).Use subtracter made of potentiometer to deduct tha dark current,restrain the voice,achieve gaining the signal.(3).Use the CY7C68013 of CYPRESS Inc to transfer large batchs of datas by USB2.0 interface quickly;(4).Use VC++6.0 completing software. Its functions are scaling the wavelength, gaining blank revising coefficient, revising the blank,etc. The software can test the soy samples,and also can display the absorbency spectrum.By our initial measure, we consider that our instrument reach our deciding request, but it still has some problems as follows. It needs our next studying.1.Use the CDS circuit to improve S/N and restrain the noise;2. Make integral time be lots of choice,and it can be adjusted by itself;3.Improve the transferring speed of the interface in order to delete the slow-storing module. 4.It still should have a lot of testing experiment on samples.