Raman probe with spatial filter and semi-confocal lens
First Claim
1. Optical apparatus for use in an instrument for identifying the composition of samples from characteristic Raman spectra comprising:
- a light source of known wavelength and deviation, transmission optics coupled to the light source so that light emitted from the light source is directed toward a sample causing the sample to produce a characteristic Raman spectrum, sampling optics situated to receive the characteristic Raman spectrum produced from the sample, the sampling optics including;
an objective lens system situated adjacent to the sample to receive radiation reflected from and emitted by the sample including the characteristic Raman spectrum produced by the sample and generate a collimated beam of the radiation, an optical filter positioned to receive the collimated beam of radiation from the objective lens and allow past primarily only a selected spectral portion including the characteristic Raman spectrum produced from the sample, a lens positioned to received the selected spectral portion passing through the optical filter and direct it toward a focal point, a spatial filter having an input positioned at about the focal point to receive the selected spectral portion and having an output, the spatial filter attenuating unwanted radiation so that the output receives substantially only the characteristic Raman spectrum produced from the sample, and an optical fiber bundle coupled to the output of the spatial filter for transmitting the characteristic Raman spectrum produced from the sample to apparatus for identifying the composition of the sample from the characteristic Raman spectra.
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Accused Products
Abstract
A material identification apparatus 10 uses a spectrograph and detector array detecting a Raman spectrum produced by a sample illuminated by a laser source to recognize a variety of materials. The Raman spectra are produced by materials illuminated by an inexpensive near-infrared multimode laser operated in a pulse mode to deliver between 0.05 and 0.5 joules of photon energy, with the Raman spectra being detected before any significant heating of the sample occurs. The identification apparatus 10 qualitatively determines the chemical composition of reinforced and unreinforced copolymers and composites such as ABS, polypropylene, talc-filled polypropylene, polycarbonate, PMMA, PVB, polyethylene, and PVC, from samples of different colors, layers, and textures with a high degree of success without the need for special sample preparation.
76 Citations
20 Claims
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1. Optical apparatus for use in an instrument for identifying the composition of samples from characteristic Raman spectra comprising:
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a light source of known wavelength and deviation, transmission optics coupled to the light source so that light emitted from the light source is directed toward a sample causing the sample to produce a characteristic Raman spectrum, sampling optics situated to receive the characteristic Raman spectrum produced from the sample, the sampling optics including;
an objective lens system situated adjacent to the sample to receive radiation reflected from and emitted by the sample including the characteristic Raman spectrum produced by the sample and generate a collimated beam of the radiation, an optical filter positioned to receive the collimated beam of radiation from the objective lens and allow past primarily only a selected spectral portion including the characteristic Raman spectrum produced from the sample, a lens positioned to received the selected spectral portion passing through the optical filter and direct it toward a focal point, a spatial filter having an input positioned at about the focal point to receive the selected spectral portion and having an output, the spatial filter attenuating unwanted radiation so that the output receives substantially only the characteristic Raman spectrum produced from the sample, and an optical fiber bundle coupled to the output of the spatial filter for transmitting the characteristic Raman spectrum produced from the sample to apparatus for identifying the composition of the sample from the characteristic Raman spectra. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. Optical apparatus for use in an instrument for identifying the composition of samples from characteristic Raman spectra comprising:
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a light source of known wavelength and deviation, transmission optics coupled to the light source so that light emitted from the light source is directed toward a sample causing the sample to produce a characteristic Raman spectrum, sampling optics situated to receive the characteristic Raman spectrum produced from the sample, the sampling optics including;
an objective lens system situated adjacent to the sample to receive radiation reflected from and emitted by the sample including the characteristic Raman spectrum produced by the sample and generate a collimated beam of the radiation, the objective lens system having a depth of field of less than 1 mm (FWHM), a focal length of less than 10 mm, and a magnification power of at least 20×
,an optical filter positioned to receive the collimated beam of radiation from the objective lens and allow past primarily only a selected spectral portion including the characteristic Raman spectrum produced from the sample, a lens positioned to received the selected spectral portion passing through the optical filter and direct it toward a focal point, a spatial filter having an input positioned at the focal point to receive the selected spectral portion and having an output, the spatial filter attenuating unwanted radiation so that the output receives substantially only the characteristic Raman spectrum produced from the sample, and an optical fiber bundle coupled to the output of the spatial filter for transmitting the characteristic Raman spectrum produced from the sample to apparatus for identifying the composition of the sample from the characteristic Raman spectra. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification