activatm glossary of terms - horiba · 2014-04-29 · 4 icp optical emission spectroscopy technical...

ACTIVATM Glossary of Terms

Jobin Yvon, Longjumeau, France

Keywords: CCD, analytical performance, glossary, solid state detector

ICP OPTICAL EMISSION SPECTROSCOPY

TECHNICAL NOTE 20

Accuracy

The accuracy of an instrument is its capacity togive results that are free of systematic error. Theaccuracy is evaluated by the difference betweenthe measured mean value and the true value ofthe element concentration.

Advance Inverted Mode Operation (AIMO) Device

An improved inverted mode device structuredeveloped to achieve peak signal levels higherthan available with the basic IMO device. Seealso Inverted Mode Operation device and Multi-Phase Pinned.

Anti-blooming Drain

The drain structure used to remove excess over-load-generated charge from the pixels of an imagesection, usually located in the column isolationregion. See also Blooming.

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TECHNICAL NOTE 20

Back-Illuminated (Back-Thinned)

A CCD fabricated on one surface of silicon materi-al which is subsequently processed for illuminationfrom the reverse side, thereby avoiding transmissionloss in the electrode layer (particularly significant atshort wavelengths or with low energy X-rays). Thisrequires the silicon to be reduced to a thin layer,which is usually achieved with chemical etching,together with surface passivation and an optionalanti-reflection coating.

(a)(b)

Figure 1: Front (a) and back-thinned illuminated (b)CCD

Binning

The addition of signal charge from more than onepixel into a given location. Binning may be per-formed in either horizontal (row) or vertical (col-umn) directions by performing the summation ontothe output node, into a summing well or into thereadout register. Binning reduces readout timewithout redaout noise penalty.

Blank

1. Matrix blankThe matrix blank is the matrix without analytes.2. Reagent blankThe reagent blank has only the reagents (acids,etc).3. Field blankA field blank is a reagent blank which follows allsteps of preparation of the sample without thesample (preparation, dilution, etc).

Binning capacity

The storage capacity of the readout register and/orsumming well relative to that of the pixel.

A semiconductor in which generated electroniccharge is accumulated and transferred by the appli-cation of electrical potentials to insulated elec-trodes or gates. In an imaging CCD the charge isgenerated by received photons, either optical or X-ray.

Figure 3: Photo of ACTIVA CCD

Figure 4: CCD principle3


TECHNICAL NOTE 20

Blooming

When the illumination level is sufficient to generatemore charge than can be stored in a pixel, thespread of excess charge to adjacent pixels is knownas blooming.

(a) (b)Figure 2: photo without blooming (a) and withblooming (b)

Channel

A region of semiconductor defined by implantationfor charge transport or conduction. In an image sen-sor this might be immediately below the surface ofthe electrode structure, hence 'surface channel', ordeeper within the material, 'buried channel'.

Charge Coupled Device (CCD)

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TECHNICAL NOTE 20

Charge Packet

An isolated quantity of charge (electrons), typical-ly consisting of the integrated photo-generatedcharge from a single pixel of the image, which isstored and transported as signal in a CCD.

Clock Phase

A term used to identify: i) the different clock puls-es, in the set of similar but time shifted pulses, usedto operate a section of a device; ii) the terminal ofthe device to which these pulses are applied and iii)the electrodes connected to this terminal. A clockphase is usually designated by the Greek symbol φ,followed by a number which generally indicatessequence (both in time for the pulses and spatiallyfor the electrodes) and preceded by a letter to indi-cate the device section to which it applies.

Clock Pulse(s)

The pulsed voltage waveform (of which several aregenerally required) applied to the device for opera-tion.

Clocking

A term used to describe operation of the device byapplying clock pulses to achieve collection, transferand detection of signal charge.

Column

A line of CCD elements in the direction perpendi-cular to the readout register and generally transfer-ring charge to one particular element in the readoutregister.

Dark Current

The output signal of an image sensor with zero illu-mination. This is typically thermally generated elec-trons within the semiconductor material which areaccumulated in each element of the device andtransferred to the output during readout.

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TECHNICAL NOTE 20

Detection limit

Smallest concentration which can be detected withcertainty with respect to a blank.

CL = k sBc/S = k c RSDB/SBRwith :CL: limit of detectionk: statistical factor (generally equals 3)sB: standard deviation of the blankc: concentration of the measured elementS: signal of the elementRSDB: relative standard deviation of the blankSBR: signal-to-background ratio

Drain

An n-type region in the device structure to which apositive bias is applied to extract electrons. Seealso Anti-blooming drain.

Dynamic range

Dynamic Range is the ratio of the maximum andminimum signal measurable. With respect to aCCD, this performance figure of merit correspondsto the ratio of the pixel’s full well saturation chargeto the output amplifier’s read-out noise

Figure 5: Response curve one pixel

Element

The basic unit cell of a CCD able to store an isolat-ed quantity or 'packet' of charge.

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TECHNICAL NOTE 20

Error

Result of a measurement minus a true value of themeasurand. Since a true value cannot be deter-mined, in practice a conventional true (or accepted)value is used. (NF X 07-001).

Exposure time

Exposure time is the time, when the shutter is onand the photons are changed into charges. In caseof a CCD, the dynamic is limited by the pixel capac-ity (see full well), so the integration time is dividedin exposure times to avoid saturation.

Figure 6: Exposure time, readout time and totaltime

Fidelity

Capacity of an instrument to give good repeatabili-ty.

Focal length

Distance between the entrance slit or the CCD andthe mirror.

An anti-blooming drain designed to remove anyexcess charge above a pre-set maximum signal level.

Fixed Anti-blooming

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TECHNICAL NOTE 20

Frame Transfer CCD

A CCD designed with the active area separatelyclocked in two sections; one for image acquisitionand one for temporary storage and subsequenttransfer to a readout register. In some CCDs a shieldis incorporated to make the storage region insensi-tive to illumination. Frame transfer devices are typi-cally used for TV applications. Integration of a sub-sequent frame may take place simultaneously withreadout.

Front Face Illuminated

The conventional mode of imaging CCD operationwhere the incident radiation is transmitted to thecharge generating silicon via polysilicon clock elec-trodes. See also Back-illuminated.

Full Frame CCD

An alternative term for storage capacity. A measureof the peak signal capability of the device, general-ly expressed as the number of electrons per pixel.

Full Well Capacity

A mode of CCD operation where all active elementsare used for imaging.

Gain

Gain is the conversion between electrons generat-ed in the CCD to counts reported in the software.

Figure 7: Gain

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TECHNICAL NOTE 20

Guard Ring / Drain

A drain structure sometimes used in the peripheralregions of a CCD to collect photo-generated chargewhich would otherwise diffuse into the activeregions of the device as spurious signal.

Integration time

The time or proportion of the operating cycle of theCCD in which charge is accumulated.


Linear Range

Linear part of the dynamic range.

Inverted Mode Operation (IMO) device

A conventional device structure fabricated withadditional implants to allow integration with all clockphases at zero and the whole surface inverted,thereby achieving very low levels of dark signal. Seealso Inverted, Pinned, Multi-Phase Pinned.

Equivalent to repeatability over a long period oftime (several hours).

Long term stability (intermediate precision)

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TECHNICAL NOTE 20

Lumigen (or Phosphor) coating

The depth of penetration into silicon is very shallowfor UV light. With this shallow penetration, theprobability of a UV photon penetrating to the deple-tion zone is less than for longer wavelength pho-tons. Thus the Quantum Efficiency (QE) is lower inthe UV than in the visible and NIR region. By coat-ing the chip with a fluorescent dye that convertsUV light to longer wavelengths, the probability ofphoton detection is increased. Lumigen is a Phos-phor coating used for UV enhancement.

(a)

(b)

Figure 8: Quantum efficiency for front illuminated(a) and Phosphor (b) coating illuminated CCD

Multi-Phase Pinned (MPP)

Alternative description of IMO devices, used partic-ularly in the USA.

Pixel

'Picture Element': an element in the image sectionof a CCD in which photo-generated charge is col-lected as signal.

Figure 9: Pixel principle

Pixel Bandpass

The Band Pass (nm) is the product of the reciprocallinear dispersion (nm/µm) by the pixel width (µm).

Potential Well

A term used to describe the charge storage region(of an element) derived from the shape of the poten-tial distribution in the underlying silicon.

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TECHNICAL NOTE 20

Precision

Corresponds to repeatability and reproducibility.

Quantum Efficiency (QE) (Optical)

A measure of the sensitivity of an image sensor toinput illumination. It is defined as the proportion ofthe incident photons which generate signal charge,and is normally expressed as a percentage. It iswavelength dependent.


Quantification Limit

Concentration corresponding to a given repeatabili-ty (for example 5 %).

Readout Noise

Noise that is generated by the CCD's on-chip out-put amplifier. This noise parameter is frequencydependent and will increase with increased pixelprocessing times.


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TECHNICAL NOTE 01

Readout Time

The readout time of a CCD is the interval requiredto move the charges from their photo-sensitivelocations to the readout register, sample and ampli-fy the charges and then digitize them into discretedigital data points.


Readout Register (or Output Register)

A CCD analogue shift register fabricated adjacentto the column structure of the device, used for seri-al readout of each row of charge signals.

Figure 4: CCD principle

Repeatability

Closeness of the agreement between the results ofsuccessive measurements of the same measurandcarried out under the same conditions of measure-ment (according to Norm NF X 07-001).

Reciprocal Linear Dispersion (RLD)

Reciprocal Linear dispersion is the spread of thespectrum in the image plane. It is expressed innm/mm. It is wavelength, focal length, groove den-sity and diffraction order dependent.

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TECHNICAL NOTE 20

Reproducibility

Closeness of the agreement between the results ofsuccessive measurements of the same measurandcarried out under changed conditions of measure-ment (according to Norm NF X 07-001). The mod-ified conditions should be specified (operator, labo-ratory, etc). Reproducibility can be within laborato-ry or between laboratories.

Resolution Power

The resolution power is the ability to separate twoemission lines which are near. It is λ/∆λ and has nounit. The resolution is ∆λ and its unit is in picome-ter (pm).

Robustness

Capacity of plasma to accept different changeswithout significant variation in element signal.These changes can come from the matrix, theoperating parameters or the environment.

The maximum signal level that can be accommo-dated by a device is its saturation level. At thispoint, further increase in input signal does notresult in a corresponding increase in output. Thisterm is often used to describe the upper limit of apixel, an amplifier, or an ADC.


Saturation

A high performance CCD not generally compatiblewith standard TV formats and typically operated atreduced temperatures to achieve a wide dynamicrange.

Scientific Sensor

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TECHNICAL NOTE 20

Sensitivity

Change in the response of a measuring instrumentdivided by the corresponding change in the stimu-lus (according to Norm NF X 07-001). It is theslope of the curve I = f(C).

Sequential Analysis

A sequential spectrometer measures one elementat one wavelength at one time. It does not measurebackground wavelength at the same time as theelement wavelength.

SimShot (Simultaneous Analysis)

Simultaneous analysis of multiple elements at mul-tiple wavelengths including background wave-lengths.

Spectral Response

The variation of responsivity with optical wave-length.

Spectroscopic Sensor

A CCD designed for use in applications where theinput illumination is spectrally dispersed in onedimension and imaged or binned in the orthogonaldirection.

Total time

Sum of the exposure times and the readout times.


1-866-Jobin.Yvon

www.jobinyvon.com

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TECHNICAL NOTE 20

In the USA:Jobin Yvon Inc.3880 Park AvenueEdison, NJ 08820Tel: 1-732-494-8660Fax: 1-732-494-8796E-mail: [email protected]

In France:Jobin Yvon S.A.S.16-18, rue du Canal91165 Longjumeau CedexTel: (33) 1/64 54 13 00Fax: (33) 1/69 09 90 88

Germany: (49) 89/46 23 17-0Italy: (39) 2/57 60 56 90U.K.: (44) 20/82 04 81 42

In Japan:Horiba Ltd.2 Miyanohigashi, KisshoinMinami-ku, Kyoto 601-8510TEL: (81) 75 313 8121FAX: (81) 75 321 5725www.horiba.com

China: (86) 10/68 49 2216Spain: (34) 91/724 16 57Other Countries: Contact JYS.A.S.

Wavelength Analytical View (WAV)

Spectral window expressed in nm within whichsimultaneous measurement of multiple elements atmultiple wavelengths with adjacent backgrounds ispossible.

WAV-Builder

Algorithm to generate a WAV. Included in ACTIVAnalyst for tailored WAV analysis.

Uncertainty of Measurement

Parameter associated with the result of a measure-ment, that characterizes the dispersion of the val-ues that could reasonably be attributed to themesurand (according to Norm NF X 07-001).

With permission from e2V technologies ltd,Waterhouse Lane, Chelmsford, Essex, CM1 2QU, England.Information subject to change without notice.

activatm glossary of terms - horiba · 2014-04-29 · 4 icp optical emission spectroscopy technical...

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