平面波产生的侧波

一、引言 側波,在地震勘探中常称为折射波,在一般的文献中又常称为首波。“折射波”这名称易和普通的折射波相混,“首波”从其含义說又沒能包括和其本属同一范畴的表面側波。但是在理論研究中,把首波和表面侧波放在一起討論比較方便,故这里就采用“侧波”这名.

SIDE-WAVES PRODUCED BY A PLANE WAVE

When a uniform longitudinal plane wave is grazing the plane surface of separation between two media from the high-speed side and when the incidence is at a finite distance, several kinds of side-waves are produced, including in particular the head wave. This contradicts the common belief that head waves are produced owing to the curvature of the incident wave front. The intensity of the incident plane wave is weakened, and the variation of the intensity is found to be similar to that of light diffraction. Definite relations exist between the intensities of side-waves and the gradient of the intensity of the original wave at the boundary. By use of such relationships, one may also calculate the intensities of side-waves produced by waves of other types.