Correction of Chemical Image Collected Using ATR Through Germanium Hemisphere

An apparatus, comprising:

• a computer including an algorithm that can perform a step of modeling simulated rays passing through a simulated germanium (Ge) hemisphere attenuated total reflection (ATR) microscope that includes a simulated Ge hemisphere and a simulated detector at a simulated detector plane, wherein said simulated Ge hemisphere ATR microscope comprises simulated parameters, wherein the step of modeling simulated rays comprises:
• determining a data set for rays reaching said detector plane;
• and
• at least once simulating the movement of said simulated Ge hemisphere along a simulated first axis and determining at least one subsequent data set;
• wherein said apparatus further comprises providing a real Ge hemisphere ATR microscope having real parameters that substantially match said simulated parameters, wherein said real Ge hemisphere ATR microscope comprises a real Ge hemisphere and a real detector at a real detector plane;
• a sample to be imaged at said detector plane, wherein said sample is in contact with said Ge hemisphere;
• means for moving, at least once, said real Ge hemisphere along a real first axis that is substantially similar to said simulated first axis and collecting a spectral image of said sample at said real detector plane, wherein said spectral image is collected for actual rays passing through said real Ge hemisphere ATR microscope and reaching said real detector plane, wherein the step of modeling simulated rays further comprises applying said data set and said at least one subsequent data set to said spectral image and said at least one subsequent spectral image to produce at least one corrected image of said sample.

A method, comprising:

• modeling the efficiency of simulated rays propagating from a simulated source through a simulated GE hemisphere ATR microscope onto a simulated detection plane, wherein said efficiency is modeled as a function of the position of said simulated rays on said simulated detection plane;
• measuring an actual blank spectrum for actual rays propagating on and about a central axis of an actual GE hemisphere ATR microscope;
• computing, using said actual blank spectrum, values for a complete blank spectrum across the entire range of positions on said sample plane;
• measuring an actual spectrum of an actual sample located at an actual sample plane of said actual GE hemisphere ATR microscope to produce an image, wherein said actual spectrum is measured across the entire range of positions for said actual rays propagating through said actual GE hemisphere ATR microscope from an actual source to an actual detection plane;
• computing values for a measured spectrum across said entire range of positions;
• modeling the average incident angle of said simulated rays reaching said sample;
• calculating a correct spectra at each position of the first image;
• modeling the average x value for rays at said simulated sample, as a function of x inferred from linear paraxial magnification;
• and
• calculating the spectral image, corrected for spatial distortion.

A method, comprising:

• developing a ray trace model of a germanium hemisphere attenuated total reflection (ATR) microscope to compute image distortion, energy throughput, and average incident angle as a function of position on a sample, including building a representative optical model of said ATR microscope, wherein said optical model includes a list of optical elements of said ATR microscope with their dimensions and relative positions in space, wherein said optical model includes as independent parameters (i) the position of an individual pixel at a detector plane, (ii) the coordinate of the Ge hemisphere relative to the optical axis of said microscope and (iii) the Y coordinate of the Ge hemisphere relative to the optical axis;
• ray tracing, using said ray trace model, rays from a modulated source to simulate the trajectory of light rays passing through said microscope;
• ray tracing, using said ray trace model, points on a hyperspectral map, wherein the step of ray tracing comprises:
• at every point, tracing a large number of rays from a single field point through a uniform distribution of points at a pupil plane;
• and
• rejecting all rays from the computation, that would not reach the detector plane;
• computing arrays of statistics for rays that reach the detector plane, wherein said statistics comprise:
• mean X position of rays incident at the sample plane;
• mean Y position of rays incident at the sample plane;
• mean incident angle at the sample plane;
• and
• percentage of traced rays that reach the detector;
• storing said arrays of data as reference data for correcting measured maps;
• measuring a background spectrum at the center of the hemisphere and calculating background spectra for the entire measurement area to produce a calculated background spectrum by multiplying the background spectrum by the position-dependent calculated energy throughput;
• collecting a chemical image as an array of ATR spectra over a region of the sample;
• dividing each spectrum of said array of ATR spectra by said computed background spectrum to produce a normalized spectrum;
• correcting said normalized spectrum for variation in incident angle to produce a normalized spectrum that represents absorption data;
• and
• correcting said normalized spectrum for spatial distortion to produce a corrected chemical map.

A method, comprising:

• modeling simulated rays passing through a simulated germanium (Ge) hemisphere attenuated total reflection (ATR) microscope comprising a simulated Ge hemisphere, wherein the step of modeling simulated rays comprises:
• determining a data set for rays reaching a simulated detector plane;
• and
• at least once simulating the movement of said simulated Ge hemisphere along a simulated first axis and determining at least one subsequent data set;
• wherein said method further comprises providing a real Ge hemisphere ATR microscope;
• providing a sample to be imaged at a real detector plane, wherein said sample is in contact with the Ge hemisphere of said real Ge hemisphere ATR microscope;
• collecting a spectral image of said sample at a real detector plane, wherein the step of collecting a spectral image comprises at least once moving said real Ge hemisphere along a real first axis that is substantially similar to said simulated first axis and collecting at least one subsequent spectral image at each increment;
• and
• applying said data set and said at least one subsequent data set to said spectral image and said at least one subsequent spectral image to produce at least one corrected image of said sample.

An apparatus, comprising:

• a computer including an algorithm that can perform a step of modeling simulated rays passing through a simulated germanium (Ge) hemisphere attenuated total reflection (ATR) microscope comprising a simulated Ge hemisphere, wherein the step of modeling simulated rays comprises:
• determining a data set for rays reaching a simulated detector plane;
• and
• at least once simulating the movement of said simulated Ge hemisphere along a simulated first axis and determining at least one subsequent data set;
• wherein said apparatus further comprises a real Ge hemisphere ATR microscope including a real Ge hemisphere;
• providing a sample to be imaged at a real detector plane, wherein said sample is in contact with the Ge hemisphere of said real Ge hemisphere ATR microscope;
• means for collecting a spectral image of said sample at a real detector plane, wherein said means for collecting a spectral image comprises means for at least once moving said real Ge hemisphere along a real first axis that is substantially similar to said simulated first axis to collect at least one subsequent spectral image at each increment;
• and
• wherein said algorithm is configured to apply said data set and said at least one subsequent data set to said spectral image and said at least one subsequent spectral image to produce at least one corrected image of said sample.