The distribution of rays was traced by placing regular-sized small dots at the center of all rays of tangential sections in sugi (Cryptomeria japonica) and tochinoki (Aesculus turbinata) to produce “dot maps”. These dot maps were set on an optical Fourier transform equipment in such a way that the axial direction of the dot maps corresponded to the vertical line. The diffraction patterns which reflect only the arrangement information of rays were recorded on photographic films.
The diffraction patterns of rays showed characteristic spots only on the equator in sugi and on the meridian in tochinoki. For the interpretation of these diffraction patterns some mathematical treatments were introduced. As the result, the arrangement of these rays on an arbitrary direction was shown to be detected by densitometry of the diffraction pattern along the direction through the origin. Ths method is useful to the two-dimensional analysis of the distribution of many tissues or cells of wood.