| 摘要 |
<p>PURPOSE:To quantitatively and accurately obtain the periodic interval, direction, symmetry of a periodic structure. CONSTITUTION:The measuring data or data stored in a file 23 is loaded into an image buffer 21 as a string of, digital signals. A selection switching circuit 25 selects a fast Fourier transform(FFT) operational circuit 28, so that the data is transferred from the image buffer 21 and Fourier-transformed in two dimension. The result of the Fourier transform is rearranged by a rearranging circuit 29 so that the zero frequency of the power spectrum is at the center of the frequency space. The rearranged data is transferred to a converting circuit 30. After the data is logarithmically converted in the circuit 30, the data is returned to the image buffer 21 again and displayed at a CRT 22.</p> |
