# US 2015/0177142 A1 · Diamond atr artefact correction > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2015/0177142 A1 - Document ID: US20150177142A1 - Status: Published application - Kind: A1 - Application number: 14/420,101 - Filed: 2013-07-23 - Published: 2015-06-25 - Earliest claimed: 2012-08-06 - Assignees: PerkinElmer Singapore PTE Ltd. - Applicants: PerkinElmer Singapore PTE Ltd - Inventors: Robert Alan Hoult - Web page: https://patentgrep.com/patent/US20150177142A1 ## CPC - G01N 21/62: Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light - G01J 3/28: Investigating the spectrum (using colour filters G01J3/51) - G01N 21/274: {Calibration, base line adjustment, drift correction} - G01N 21/552: Attenuated total reflection - G01N 2201/1218: for pressure variations - G01N 2201/12784: Base line obtained from computation, histogram - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N) ## Abstract A method of using a spectrometer to produce corrected diamond Attenuated Total Reflectance (ATR) spectral data includes acquiring, using the spectrometer, an initial set of ATR spectral data for a sample pressed into contact with a diamond ATR crystals; numerically matching, using the spectrometer, a pressure dependent diamond artefact reference spectrum to a corresponding pressure dependent diamond artefact in the initial set of ATR spectral data; and numerically subtracting out the numerically matched pressure dependent diamond artefact reference spectrum from the initial set of ATR spectral data to yield a corrected set of ATR spectral data for the sample for output by the spectrometer. ## Claims ### Claim 1 A method of using a spectrometer to produce corrected diamond Attenuated Total Reflectance (ATR) spectral data comprising the steps of: acquiring, using the spectrometer, an initial set of ATR spectral data for a sample pressed into contact with a diamond ATR crystal; numerically matching, using the spectrometer, a pressure dependent diamond artefact reference spectrum to a corresponding pressure dependent diamond artefact in the initial set of ATR spectral data; and numerically subtracting out the numerically matched pressure dependent diamond artefact reference spectrum from the initial set of ATR spectral data to yield a corrected set of ATR spectral data for the sample for output by the spectrometer. ### Claim 2 (depends on 1) A method according to claim 1 in which the numerically matching step comprises adjusting the magnitude of the artefact reference spectrum. ### Claim 3 (depends on 1) A method according to claim 1 in which the numerically matching step comprises adjusting for differences in abscissa scales associated with the reference spectrum and the initial set of spectral data. ### Claim 4 (depends on 2) A method according to claim 2 in which the step of adjusting the magnitude of the artefact reference spectrum comprises finding a magnitude that yields a best fit between the pressure dependent diamond artefact reference spectrum and the corresponding pressure dependent diamond artefact in the initial set of ATR spectral data. ### Claim 5 (depends on 4) A method according to claim 4 in which the step of adjusting the magnitude of the artefact reference spectrum comprises the steps of: i) finding a magnitude that yields a best fit between the pressure dependent diamond artefact reference spectrum and the corresponding pressure dependent diamond artefact in the initial set of ATR spectral data; ii) identifying at least one data point from the best fit as an outlier; iii) suppressing said at least one data point and finding a modified magnitude that yields a modified best fit between the pressure dependent diamond artefact reference spectrum and the corresponding pressure dependent diamond artefact in the initial set of ATR spectral data with said at least one data point suppressed. ### Claim 6 (depends on 5) A method according to claim 5 in which the identifying and the suppressing and the finding are iterated suppressing further data points in each iteration. ### Claim 7 (depends on 3) A method according to claim 3 in which the step of adjusting for differences in abscissa scales comprises the step of: comparing a spectrometer specific standard ATR spectral data for a standard sample substance with a reference set of standard ATR spectral data for the standard sample substance. ### Claim 8 (depends on 7) A method according to claim 7 in which the standard sample substance is diamond. ### Claim 9 (depends on 7) A method according to claim 7 in which the step of adjusting for differences in abscissa scales comprises the steps of: first adjusting for differences in abscissa scales based on the comparison between the spectrometer specific standard ATR spectral data and the reference set of standard ATR spectral data for the standard sample substance; and after this further adjusting for differences in abscissa scales based on a comparison between the pressure dependent diamond artefact reference spectrum and the corresponding pressure dependent diamond artefact in the initial set of ATR spectral data. ### Claim 10 (depends on 1) A method according to claim 1 in which the numerically matching step comprises pre-processing at least one of the sets of ATR spectral data and/or pre-processing the pressure dependent diamond artefact reference spectrum to suppress slow baseline variation. ### Claim 11 (depends on 7) A method according to claim 7 in which the step of adjusting for differences in abscissa scales comprises the steps of: determining an abscissa shifted version of the reference set of standard ATR spectral data; determining a difference spectrum from the difference between the abscissa shifted version of the reference set of standard ATR spectral data and the original reference set of standard ATR spectral data; determining a trial spectrum by adding a scaled amount of the difference spectrum to the original reference set of standard ATR spectral data, the scaled amount being characterised by a shift scale factor; fitting the trial spectrum to the set of spectrometer specific standard ATR spectral data by varying the shift scale factor to obtain the best fit; and determining an appropriate abscissa scale adjustment in dependence on the shift scale factor corresponding to the best fit. ### Claim 12 (depends on 7) A method according to claim 7 in which the step of adjusting for differences in abscissa scales comprises the steps of: determining an abscissa shifted version of the reference set of standard ATR spectral data; determining a difference spectrum from the difference between the abscissa shifted version of the reference set of standard ATR spectral data and the original reference set of standard ATR spectral data; determining the first derivative of the difference spectrum, the first derivative of the original reference set of standard ATR spectral data, and the first derivative of the set of spectrometer specific standard ATR spectral data; determining a trial spectrum by adding a scaled amount of the first derivative of the difference spectrum to the first derivative of the original reference set of standard ATR spectral data, the scaled amount being characterised by a shift scale factor; fitting the trial spectrum to the first derivative of the set of spectrometer specific standard ATR spectral data by varying the shift scale factor to obtain the best fit; and determining an appropriate abscissa scale adjustment in dependence on the shift scale factor corresponding to the best fit. ### Claim 13 (depends on 12) A method according to claim 12, in which the step of adjusting for differences in abscissa scales comprises the steps of: adjusting the pressure dependent diamond artefact reference spectrum in dependence on the determined abscissa scale adjustment to give an adjusted artefact reference spectrum; determining an abscissa shifted version of the adjusted artefact reference spectrum; determining a difference spectrum from the difference between the abscissa shifted version of the adjusted artefact reference spectrum and the original adjusted artefact reference spectrum; determining the first derivative of the difference spectrum, the first derivative of the original adjusted artefact reference spectrum, and the first derivative of the initial set of ATR spectral data; determining a trial spectrum by adding a scaled amount of the first derivative of the difference spectrum to the first derivative of the original adjusted artefact reference spectrum, the scaled amount being characterised by a shift scale factor; fitting the trial spectrum to the first derivative of the initial set of ATR spectral data by varying the shift scale factor to obtain the best fit; and determining a further appropriate abscissa scale adjustment in dependence on the shift scale factor corresponding to the best fit. ### Claim 14 (depends on 1) A method according to claim 1 in which the numerically matching step comprises the step of adjusting the resolution of the diamond artefact reference spectrum to match the resolution of the initial set of ATR spectral data. ### Claim 15 (depends on 1) A method according to claim 1 in which the step of adjusting the magnitude of the artefact reference spectrum includes the determination of at least one magnitude coefficient and the step of adjusting for differences in abscissa scales includes the determination of at least one shift coefficient and the method comprises the step of checking whether the at least one magnitude coefficient satisfies at least one respective threshold and checking whether the at least one shift coefficient satisfies at least one respective threshold. ### Claim 16 (depends on 1) A method according to claim 1 in which the step of numerically subtracting out the numerically matched pressure dependent diamond artefact reference spectrum may comprise dividing in transmittance. ### Claim 17 A spectrometer arranged for performing Attenuated Total Reflectance (ATR) measurements comprising: a source of radiation; a detector for detecting radiation having passed through a diamond ATR crystal positioned in the spectrometer; and a processing unit for processing the output of the detector to produce sets of ATR spectral data; wherein the spectrometer has a memory for storing a pressure dependent diamond artefact reference spectrum and is arranged to acquire an initial set of ATR spectral data for a sample pressed into contact with a diamond ATR crystal; and the processing unit is arranged to: numerically match the pressure dependent diamond artefact reference spectrum to a corresponding pressure dependent diamond artefact in the initial set of ATR spectral data; and numerically subtract out the numerically matched pressure dependent diamond artefact reference spectrum from the initial set of ATR spectral data to yield a corrected set of ATR spectral data for the sample for output by the spectrometer. ### Claim 18 A method of producing corrected diamond Attenuated Total Reflectance (ATR) spectral data comprising the steps of: obtaining a pressure dependent diamond artefact reference spectrum on a, first, reference spectrometer; acquiring, using a second spectrometer, an initial set of ATR spectral data for a sample pressed into contact with a diamond ATR crystal; numerically matching, using the second spectrometer, the pressure dependent diamond artefact reference spectrum to a corresponding pressure dependent diamond artefact in the initial set of ATR spectral data; and numerically subtracting out the numerically matched pressure dependent diamond artefact reference spectrum from the initial set of ATR spectral data to yield a corrected set of ATR spectral data for the sample for output by the second spectrometer. ### Claim 19 A method of obtaining a pressure dependent diamond artefact reference spectrum for use in producing corrected diamond Attenuated Total Reflectance (ATR) spectral data, the method comprising the steps of: providing a diamond ATR crystal in a reference spectrometer and pressing a reference sample against the ATR crystal; varying the applied pressure with which the reference sample is pressed against the ATR crystal; obtaining, using the reference spectrometer, spectra for the reference sample at a plurality of applied pressures; determining pressure dependent features in the resulting spectra; determining at least one region in the spectrum exhibiting pressure dependence; generating a pressure dependent diamond artefact reference spectrum by restricting the range of the spectrum to said at least one region and including only features determined as pressure dependent in the respective determining step. ### Claim 20 A method of correcting diamond Attenuated Total Reflectance (ATR) spectral data comprising the steps of: receiving an initial set of ATR spectral data for a sample pressed into contact with a diamond ATR crystal; numerically matching a pressure dependent diamond artefact reference spectrum to a corresponding pressure dependent diamond artefact in the initial set of ATR spectral data; and numerically subtracting out the numerically matched pressure dependent diamond artefact reference spectrum from the initial set of ATR spectral data to yield a corrected set of ATR spectral data for the sample. ### Claim 21 A computer for correcting diamond Attenuated Total Reflectance (ATR) spectral data arranged under the control of software to: receive an initial set of ATR spectral data for a sample pressed into contact with a diamond ATR crystal; numerically match a pressure dependent diamond artefact reference spectrum to a corresponding pressure dependent diamond artefact in the initial set of ATR spectral data; and numerically subtract out the numerically matched pressure dependent diamond artefact reference spectrum from the initial set of ATR spectral data to yield a corrected set of ATR spectral data for the sample. ### Claim 22 (depends on 20) A machine readable data carrier carrying a computer program comprising code portions which when loaded and run on a computer cause the computer to carry out the method of claim 20.