To address the issues in infrared thermography detection technology

such as the strong dependence of pulsed thermography on excitation light energy

shallow detection depth

excessively high excitation power

and complex equipment structure

this paper adopts an infrared thermography detection method based on linear frequency modulation pulse thermography. This approach aims to achieve effective detection of deep-seated defects in power insulation equipment under low-power conditions. First

a thermal radiation model of the excitation light source acting on the test specimen is established

and the excitation principle of linear frequency modulation pulse thermography is explained. Then

this paper builds a corresponding experimental platform to conduct tests on carbon fiber composite panels under different excitation powers. Finally

algorithms such as fast Fourier transform(FFT) transform

cross-correlation operation

and principal component analysis are employed to process the experimental data

and the results are compared with those of pulsed thermography. The results show that linear frequency modulation pulse thermography can effectively characterize deep-seated defects

with the Fast Fourier Transform(FFT) phase providing the best characterization performance. For defects deeper than 2 mm

this method significantly improves the detection signal-to-noise ratio. Moreover

the detection performance for deep-seated defects is weakly correlated with excitation power

enabling effective detection of deeper defects at lower power levels. This paper provides a reference for the development of portable infrared thermography detection devices and their application in complex environments for multi-target detection.