DETECTION OF INTERNAL INFORMATION OF SOLID SAMPLE BY PHOTO-ACOUSTIC METHOD

摘要

PURPOSE:To detect photo-acoustic (PA) signals in all frequency areas at one time by Fourier transformation of PA signal obtained when a mono pulse laser beam irradiates a solid sample. CONSTITUTION:The laser beam 2 from a pulse laser sorce 1 irradiates a solid sample 8 arranged in a cell 7 through lenses 3 and 4, a mirror 5 and a lens 6 and PA signal is detected with a detector 9 such as microphone. This detected PA signal is once recorded in a wave memory 10 and undergoes Fourier transformation with a Fourier transforming device 11 and then a frequency-dependent characteristics of the amplitude and phase of the PA signal are indicated on a display unit 12 such as X-Y plotter. Depthwise optical and thermal distribution inside the sample are obtained from these dependent characteristics to find optical, thermal and physical natures of the sample.