The existing infrared thermal imaging detection methods usually process the whole video stream data collected by a thermal camera, which involve large amounts of data and have a negative effect on the efficiency of defect detection. In this paper, we propose an infrared thermal imaging detection method which considers the spatial correlation of the adjacent images in the video stream data. By extracting the edge information and analyzing the correlation between two adjacent frames, the defect area and the non-defect area show different correlation coefficients, and only part of the video data is required for defect detection. Furthermore, the fusion method is introduced to enhance the image quality. The experiment results demonstrate that the proposed method can not only reflect the change of heat in the defect area during the heating process but also reduce computation time involved in the subsequent processing.
An extrinsic Fabry-Perot interferometric fibre microphone based on polydimethylsiloxane, or PDMS, diaphragm was proposed. The large free-standing PDMS diaphragm, with a diameter of 4 mm, is prepared by a simple “spin-strip” process. The experimental result shows that the fabricated sensor has a high dynamic pressure sensitivity of about -136 dB re 1 rad/μPa in the range of 100~2000Hz. The noise equivalent acoustic signal level of the microphone, limited by the environmental noise, is about 1000 μPa/Hz<sup>1/2</sup>. And the dynamic range is tested to be more than 47.48 dB. The proposed microphone is expected to be used in the field of weak acoustic pressure testing.