Thermographic phosphor digital image correlation
| DWPI Title: Ratio method for phosphor thermography using e.g. machine vision cameras, for full-field temperature measurements e.g. temperature sensitive paints, of solid surface, involves inferring spatially resolved temperature image of specimen from spatially resolved intensity ratios |
| Abstract: The invention advances the ratio method of phosphor thermography using two machine vision cameras for full-field temperature measurements of a solid surface. As an example, algorithms from digital image correlation (DIC) can be used to determine the stereoscopic imaging system intrinsic and extrinsic parameters, and accurately register material points on the sample to subpixel locations in each image with 0.07 px or better accuracy. A phosphor calibration sample fabricated using aerosol deposition can be used for in situ determination of the temperature-versus-intensity ratio relationship. The full calibration methodology and several improvements on two-color phosphor thermography open the door for full-field temperature measurements in dynamic tests with deforming test specimens. In particular, thermographic phosphors can be combined with stereo digital image correlation in a novel diagnostic, TP+DIC, to measure time-resolved full-field surface strains and temperatures simultaneously, thereby enabling testing in combined thermo-mechanical environments. |
| Use: Ratio method for phosphor thermography using two machine vision cameras, charge-coupled device (CCD) or complementary metal oxide semiconductor (CMOS) detectors and digital image correlation for full-field temperature measurements such as temperature sensitive paints (TSP), pyrometry, and infrared (IR) thermography, of a solid surface. |
| Advantage: The method enables providing a time-resolved, full-field thermographic image of the specimen, and characterizing strain and temperature fields of a test specimen simultaneously. |
| Novelty: The method involves collecting and spectrally filtering emission of thermographic phosphor for exposure time into a first spectral band image of a first camera and a second spectral band image of a second camera of a stereoscopic imaging system. First and second spectral band images are spatially registered using stereo digital image correlation. Ratios of intensities of the first and second spectral bands are calculated for each pixel of the spatially registered spectral band images. A spatially resolved temperature image of the specimen is inferred from the spatially resolved intensity ratios using a temperature-vs-intensity ratio calibration curve for providing a time-resolved, full-field thermographic image of the specimen, where the temperature-vs-intensity ratio calibration curve is generated pixel-wise by an in-situ calibration procedure. |
| Filed: 6/13/2022 |
| Application Number: US17838777A |
| Tech ID: SD 15911.0 |
| This invention was made with Government support under Contract No. DE-NA0003525 awarded by the United States Department of Energy/National Nuclear Security Administration. The Government has certain rights in the invention. |
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