Spectral filter system for infrared imaging of substrates through coatings
First Claim
1. A system for imaging the surface of a substrate through a coating on the substrate, comprising:
- a detector positioned to receive infrared radiation from the substrate surface; and
at least one narrow bandwidth spectral optical filter between the substrate and the detector to pass infrared wavelengths from 3.75 to 5.0 micrometers to the detector.
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Accused Products
Abstract
An improved system for visual inspection of substrates coated with paints and polymers is disclosed. Painted substrates can be inspected for environmental and physical damage such as corrosion and cracks without removing the paint. The present invention provides the ability to maximize paint thickness penetration. This is accomplished with a spectral bandpass filter that rejects reflected light from the coating opaque bands, while allowing light in the paint window to pass to an IR detector such as an IR camera focal plane. The narrow bandpass range enhances the ability for IR imaging to see through thicker paint layers and improves the contrast over standard commercial IR mid-wave cameras. The bandpass may be adjusted to coincide with the full spectral window of the paint, consistent with the ability of the imaging focal plane to detect light in the spectral region.
44 Citations
24 Claims
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1. A system for imaging the surface of a substrate through a coating on the substrate, comprising:
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a detector positioned to receive infrared radiation from the substrate surface; and
at least one narrow bandwidth spectral optical filter between the substrate and the detector to pass infrared wavelengths from 3.75 to 5.0 micrometers to the detector. - View Dependent Claims (2, 3, 4, 5, 7, 8, 9, 10, 11, 12, 13, 14)
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6. The system of claim 6, wherein the infrared camera detects mid-infrared radiation having wavelengths between about 3 and about 5 microns.
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15. A method for imaging the surface of a substrate through a coating on the substrate, comprising:
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generating infrared light from the substrate;
filtering the infrared light with a narrow bandwidth filter which passes wavelengths within a range of from 3.75 to 5.0 micrometers; and
receiving the filtered infrared light on a detector. - View Dependent Claims (16, 17, 18, 19, 20, 22, 23, 24)
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Specification