System and Method for Improved Forensic Analysis
A system and method for analyzing a forensic sample. A forensic sample is illuminated nondestructively with light of a first wavelength λ 1 . A first image of the forensic sample is imaged using light emitted at a second wavelength λ 2 , the second wavelength filtered by a multi-conjugate tunable filter. A second image of the forensic sample is imaged using the light emitted from the sample at a third wavelength λ 3 , different from λ 2 , the third wavelength filtered by a multi-conjugate tunable filter. A calculated image of the forensic image is then created from the first image and the second image. The disclosure also provides for obtaining a processed image by applying a chemometric technique to the calculated image and for identifying the sample as a known forensic material by searching a reference database for a match to either the calculated image or the processed image.
1 . A method comprising:
illuminating nondestructively a forensic sample with light of a first wavelength λ 1 ;
imaging a first image of the forensic sample using the light emitted from the sample at a second wavelength λ 2 , the second wavelength filtered by a multi-conjugate tunable filter;
imaging a second image of the forensic sample using the light emitted from the sample at a third wavelength λ 3 , different from λ 2 , the third wavelength filtered by a multi-conjugate tunable filter; and
creating a calculated image of the forensic sample from the first image and the second image.
2 . The method of claim 1 further comprising applying a chemometric technique to said calculated image to thereby obtain a processed image.
3 . The method of claim 2 wherein said chemometric technique is selected from a group consisting of: principal component analysis (PCA), Partial Least Squares Discriminate Analysis (PLSDA), Cosine Correlation Analysis (CCA), Euclidian Distance Analysis (EDA), k-means clustering, multivariate curve resolution (MCR), Band T. Entropy Method (BTEM), k means clustering, Mahalanobis Distance (MD), Adaptive Subspace Detector (ASD), Spectral Mixture Resolution, and combinations thereof.
4 . The method of claim 1 wherein said image is a spatially-accurate wavelength resolved image.
5 . The method of claim 1 wherein said image is an image selected from the group consisting of: a Raman image, an infrared image, a near infrared image, a short wave infrared image, a mid infrared image, a fluorescence image, an ultraviolet image, a visible image, and combinations thereof.
6 . The method of claim 1 further comprising correcting the calculated image using signals extracted from at least one of the first and second images, wherein said signal is extracted from a subset of pixels from at least one of the first and second image pixels.
7 . The method of claim 6 wherein the subset of at least one of the first and second image pixels is a subset chosen outside an area of interest of the at least one of the first and second images.
8 . The method of claim 7 wherein said area of interest comprises an area containing at least one of: a suspected fingerprint, ink, suspected gunshot residue, suspected condom residue, a multi-layer paint chip, a fiber, a thin layer chromatography plate, and combinations thereof.
9 . The method of claim 7 wherein the correcting of the calculated image comprises subtracting a background signal provided by light of a wavelength λ from outside an area of interest from the image formed by light of wavelength λ 3 and λ 2 where λ is λ 3 or λ 2 or another wavelength.
10 . The method of claim 1 wherein the forensic sample is selected from the group consisting of: an object carrying a suspected fingerprint, an object carrying ink, an object carrying suspected gunshot residue, an object carrying a suspected condom lubricant, a multilayer paint chip, a fiber, a thin layer chromatography plate, and combinations thereof.
11 . The method of claim 1 further comprising:
providing a reference database comprising a plurality of reference data sets wherein each reference data set comprises at least one image representative of a known forensic material;
searching said reference database to thereby identify a reference data set therein that matches said calculated image to thereby classify the sample as a known forensic material.
12 . A method comprising:
illuminating nondestructively a forensic sample with light of a first wavelength λ 1 ;
imaging a first image of the forensic sample using the light emitted from the sample at a second wavelength λ 2 , the second wavelength filtered by a multi-conjugate tunable filter;
imaging a second image of the forensic sample using the light emitted from the sample at a third wavelength λ 3 , different from λ 2 , the third wavelength filtered by a multi-conjugate tunable filter;
creating a calculated image of the forensic sample from the first image and the second image;
applying a chemometric technique to said calculated image to thereby obtain a processed image.
13 . The method of claim 12 further comprising:
providing a reference database comprising a plurality of reference data sets wherein each reference data set comprises at least one image representative of a known forensic material;
searching said reference database to thereby identify a reference data set therein that matches said processed image to thereby classify the sample as a known forensic material.
14 . The method of claim 12 wherein said chemometric technique is selected from a group consisting of: principal component analysis (PCA), Partial Least Squares Discriminate Analysis (PLSDA), Cosine Correlation Analysis (CCA), Euclidian Distance Analysis (EDA), k-means clustering, multivariate curve resolution (MCR), Band T. Entropy Method (BTEM), k means clustering, Mahalanobis Distance (MD), Adaptive Subspace Detector (ASD), Spectral Mixture Resolution, and combinations thereof.
15 . The method of claim 14 wherein said image is a spatially-accurate wavelength resolved image.
16 . The method of claim 14 wherein said image is an image selected from the group consisting of: a Raman image, an infrared image, a near infrared image, a short wave infrared image, a mid infrared image, a fluorescence image, an ultraviolet image, a visible image, and combinations thereof.
17 . The method of claim 14 further comprising correcting the calculated image using signals extracted from at least one of the first and second images, wherein said signal is extracted from a subset of pixels from at least one of the first and second image pixels.
18 . The method of claim 17 wherein the subset of at least one of the first and second image pixels is a subset chosen outside an area of interest of the at least one of the first and second images.
19 . The method of claim 18 wherein said area of interest comprises an area containing at least one of: a suspected fingerprint, ink, suspected gunshot residue, suspected condom residue, a multi-layer paint chip, a fiber, a thin layer chromatography plate, and combinations thereof.
20 . The method of claim 18 wherein the correcting of the calculated image comprises subtracting a background signal provided by light of a wavelength λ from outside an area of interest from the image formed by light of wavelength λ 3 and λ 2 where λ is λ 3 or λ 2 or another wavelength.
21 . The method of claim 14 wherein the forensic sample is selected from the group consisting of: an object carrying a suspected fingerprint, an object carrying ink, an object carrying suspected gunshot residue, an object carrying a suspected condom lubricant, a multilayer paint chip, a fiber, a thin layer chromatography plate, and combinations thereof.