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利用数字信号处理技术,可直接应用微机而不用锁定放大器来检测物质的光声信号。本文给出用互功谱技术和多次平均方法所得的一些实验结果。当炭黑和黄色金刚石粉末为试样时,用微机和用锁定放大器所得到的光声信号的相位和幅值都非常吻合。文章还给出了用这数字信号处理技术检测一些薄型不透光试样的热扩散率的实验结果。这些结果与用激光导热仪所测得的结果也良好地相符合。
The use of digital signal processing technology, can be directly applied to the computer without the lock-in amplifier to detect the material’s photoacoustic signal. In this paper, some experimental results obtained by cross-spectral technique and multiple averaging methods are given. When carbon black and yellow diamond powder were used as samples, the phase and amplitude of the photoacoustic signals obtained by the microcomputer and the lock-in amplifier were in good agreement. The article also gives the experimental results of using this digital signal processing technique to detect the thermal diffusivity of some thin opaque samples. These results are also in good agreement with the results measured with the laser thermal conductivity meter.