Dissertation > Industrial Technology > Machinery and Instrument Industry > Instruments, meters > Optical instruments > Physical optical instruments > Spectrometers

The Design of Digital Spectrophotometer

Author WuBin
Tutor LiBaoHua
School Jilin University
Course Circuits and Systems
Keywords Spectrophotometer Pulse Width Modulator PMT SCM
CLC TH744.1
Type Master's thesis
Year 2005
Downloads 352
Quotes 2
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Optical analytic method is to use the absorption spectrum or emissionspectrum displayed by the component being measured. It concludes not onlyatomic spectrum, but also molecular spectrum. The analytic methods ofusing absorption spectrum created by the molecular of component beingmeasured, are the visible and UV light spectrophotometric method and theinfra-red sepectrometry; The analytic method of using emission spectrum isthe fluorophotometric method; The analytic methods using the emissionspectrum of the component being measured, conclude the emission spectrumanalytic method, atomic fluorescent method, X-ray atomic fluorescentmethod, protonic fluorescent method.Spectrophotometric method uses the molecular absorption spectrum toanalyze substance structure. As the molecular absorption spectrum isrelevant with substance structure, and the absorbance is relevant with thecontent of substance, we can analyze substance by the shape and theabsorbing degree of the absorption spectrum. This is the spectrophotometricmethod.The instrument using the spectrophotometric method and technique iscalled spectrophotometer. The spectrophotometer is the instrument whichproduces homogeneous light and uses it to expose the sample, and thenmeasure the sample’s transmissivity of homogeneous light. There are twentypercent to thirty percent of analytic work are done by spectrophotometers.The spectrophotometers are applied widely in many fields, such asagriculture, medicine, environment, chemical analysis, etc.A spectrophotometer is composed of lamp-house, monochromator,absorption cell, photodetector and signal display system. Themonochromator transform the complex light that coming from thelamp-house into monochromatic light, and when this monochromatic lightgoes across the absorption cell, the sample liquor absorb some of the light,and then the photodetector receive the left light and transform the light signalinto electric signal, at last the signal display system display the result.Among the photoconducting device being used today, thephotomultiplier is a excellent one with high sensitivity and fast responsetime. It responses fast, has low cost, and has large area cathode. thephotomultiplier is a kind of vacuo device. It is composed of photocathode,focus electrode, dynode and anode. It has two type: end window

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