Compact hyperspectral mid-infrared spectrometer
AssigneeCalifornia Institute of Technology
InventorsAxel Scherer, Taeyoon Jeon
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Abstract
An infrared spectrometer for operation in the mid-infrared spectral range is presented, where the spectrometer includes a Bragg-mirror-based spectral filter that is operative for providing an interrogation signal whose spectral content is dispersed along a first direction at a filter aperture. The filter aperture is imaged through a sample by a thermal-imaging camera to create a focused image that is based on the interrogation signal and the absorption characteristics of the sample. As a result, embodiments in accordance with the present disclosure can be smaller, less complex, and less expensive than infrared spectrometers known in the prior art.
Claims26
A spectrometer (100) for analyzing a sample (110), the spectrometer being configured for operation in the mid-infrared spectral range, and the spectrometer comprising:
- a source (102) that provides a source signal (112) having a first spectral range (SR1) that includes a plurality of wavelength signals (λ1-λn), wherein each wavelength signal of the plurality thereof is characterized by a different wavelength;
- a spectral filter (104) that receives the source signal at a first surface (116-1) and provides at least a portion of the source signal as an interrogation signal (114) at a filter aperture (118) included in a second surface (116-2), wherein the interrogation signal has a second spectral range (SR2) that includes the plurality of wavelength signals, the second spectral range being within the mid-infrared spectral range, and wherein the plurality of wavelength signals is dispersed along a first direction at the filter aperture;
- and
- a camera (106) that includes a lens (124) and a plurality of detector elements (130), wherein the camera is operative for providing an output signal (136) based on light incident on the plurality of detector elements;
- wherein the camera and spectral filter are arranged such that the camera images the filter aperture through the sample and forms an image (118′) of the filter aperture that is focused on the plurality of detector elements such that each detector element receives a different image-portion (132) of the image.
A mid-infrared (MIR) spectrometer (100) for analyzing a sample (110), the spectrometer comprising:
- a source (102) that provides a source signal (112) having a first spectral range (SR1) that includes a plurality of wavelength signals (λ1-λn), each of the plurality of wavelength signals being within the MIR spectral range, wherein each wavelength signal of the plurality thereof is characterized by a different wavelength;
- a spectral filter (104) that receives the source signal at a first surface (116-1) and provides at least a portion of the source signal as an interrogation signal (114) at a filter aperture (118) included in a second surface (116-2), the interrogation signal having a second spectral range (SR2) that includes the plurality of wavelength signals, wherein the plurality of wavelength signals is dispersed along a first direction at the filter aperture;
- and
- a camera (106) that includes a plurality of detector elements (130) and a lens (124) having a focal length (f1) that defines an object distance (128), wherein the camera is operative for providing an output signal (136) based on light incident on the plurality of detector elements;
- wherein the camera and spectral filter are arranged such that the filter aperture is located at the object distance, and wherein the sample is between the lens and the spectral filter.
A method for analyzing a sample (110), the method including:
- providing an interrogation signal (114) at a filter aperture (118) of a spectral filter (104), wherein the interrogation signal includes a plurality of wavelength signals (λ1-λn) that are dispersed along a first direction at the filter aperture, and wherein the plurality of wavelength signals are within the mid-infrared spectral range;
- imaging the filter aperture through the sample to form an image (118′) that is focused at a focal-plane array (122) comprising a plurality of detector elements (130), wherein the image is based on the interrogation signal and an absorption spectrum of the sample, and wherein each detector element receives a different image-portion (132) of the image and provides a detector output (134) that is based on the intensity of the image-portion it receives;
- and
- providing an output signal (136) that includes the plurality of detector outputs.
Dependencies are inferred from the claim text.