ASTM_E_2642_-_09_2015.pdf

Designation:E264209(Reapproved 2015)Standard Terminology forScientific Charge-Coupled Device(CCD)Detectors1This standard is issued under the fixed designation E2642;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This terminology brings together and clarifies the basicterms and definitions used with scientific grade cooled charge-coupled device(CCD)detectors,thus allowing end users andvendors to use common documented terminology when evalu-ating or discussing these instruments.CCD detectors aresensitive to light in the region from 200 to 1100 nm and theterminology outlined in the document is based on the detectiontechnology developed around CCDs for this range of thespectrum.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.2.Referenced Documents2.1 ASTM Standards:2E131 Terminology Relating to Molecular Spectroscopy3.Significance and Use3.1 This terminology was drafted to exclude any commer-cial relevance to any one vendor by using only general termsthat are acknowledged by all vendors and should be revised ascharge-coupled device(CCD)technology matures.This termi-nology uses standard explanations,symbols,and abbreviations.4.Terminology4.1 Definitions:advanced inverted mode operation(AIMO),na commer-cial tradename given to a method of reducing the rate ofgeneration of dark current.Also known as multi-pinnedphase operation.analog-to-digital(A/D)converter,nan electronic circuitryin a CCD detector that converts an analog signal into digitalvalues,which are specified in terms of bits that can bemanipulated by the computer.anti-blooming structure,na structure built into the pixel toprevent signal charge above full-well capacity from bloom-ing into adjacent pixels.DISCUSSIONAnti-blooming structures bleed off any excess chargebefore they can overflow the pixel and thereby stop blooming.Thesestructures can reduce the effective quantum efficiency and introducenonlinearity into the sensor.antireflective(AR)coating,na coating applied to either thefront surface of the CCD or the vacuum window surfaces,tominimize the amount of reflected energy(or electromagneticradiation)so as to maximize the amount of transmittedenergy.back-illuminated CCD(BI CCD),na type of CCD that hasbeen uniformly reduced in thickness on the side away fromthe gate structure(see Fig.1b)and positioned such that thephotons are detected on that side.DISCUSSIONA BI CCD leads to an improvement in sensitivity toincoming photons from the soft X-ray to the near-infrared(NIR)regions of the spectrum with the highest response in the visible region.However,compared to a front-illuminated CCD,it suffers from higherdark currents and interference fringe formation(etaloning)usually inthe NIR region.Also called back-thinned CCD.binning,nthe process of combining charge from adjacentpixels in a CCD prior to read out.DISCUSSIONThere are two main types of binning:(1)verticalbinning and(2)horizontal binning(see Fig.2).Summing charge on theCCD and doing a single readout results in better noise performancethan reading out several pixels and then summing them in the computermemory.This is because each act of reading out contributes to noise(see noise).CCD bias,nthe minimum analog offset added to the signalbefore the A/D converter to ensure a positive digital outputeach time a signal is read out.DISCUSSIONThe CCD bias is set at the time of manufacture andremains set over the lifetime of the camera.charge,nmeasure of number of electrons that are containedin a pixel potential well.charge-coupled device(CCD),na silicon-based semicon-ductor chip consisting of a two-dimensional matrix of photosensors or pixels(see Fig.3).1This terminology is under the jurisdiction of ASTM Committee E13 onMolecular Spectroscopy and Separation Science and is the direct responsibility ofSubcommittee E13.08 on Raman Spectroscopy.Current edition approved May 1,2015.Published June 2015.Originallyapproved in 2008.Last previous edition approved in 2009 as E2642 09.DOI:10.1520/E2642-09R15.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 DISCUSSIONThe matrix is usually referred to as the image area.Electronic charge is accumulated on the image area and transferred outby the application of electrical potentials to shielded electrodes.Thesize of pixels in the sensor is typically 26 26 m;however,sensorscan be manufactured in a variety of different pixel sizes ranging from6 6 m to 50 50 m.Although