Annual Report 2000 - WIT

Annual Report 2000 - WIT Annual Report 2000 - WIT

02.12.2014 Views

Elements of the surface-to-surface propagator matrix Ì Ö ¬ ž ž £ × ¯ ž ž £ ž ž ž · · ž £ £ ž à ž · ž £ G à £ · £ ž · £ Ð ž ' ¸ · · & Ð Ã ž · £ ž Ü 32 APPENDIX A Following (Hubral et al., 1992a; jCervený, 1999; Schleicher et al., 2001), we can express for the 2-D case the ÍÀÎ submatrices ÏÑÐ Ð of the ÈÕÀÂÈ surfaceto-surface propagator Ì matrix 1993) form by (Bortfeld, 1989; Hubral et al., 1992a; Schleicher et al., ¤Ò ^Ó ¤Ô (A-1) ° Ö ¯ '@Ö ˆ× (A-2) ˆ× £ka ž × £ Ö ¯ × £ Ö ˆ× (A-3) ¾ ž žI' £ia ž × £ Ö (A-4) £ a ¯ ¿ propagator a ¯ a Ö ¯ where Ö and are the scalar elements of the Ø so-called matrix (Popov and Pjsenjc´ffk, 1978; jCervený, 1985; Hubral et al., 1992a). The matrix is defined in a Cartesian coordinate system and the propagator matrix Ù is defined Ì in a ray centered coordinate system ( jCervený, 1987). We assume a 2-D model (Figures 6.1 and 6.2) with a curved measurement surface. We have a source point ¢ coinciding with the receiver point ¤ . In the paraxial vicinity of the normal ray surface location ¢Œ¤ , where the medium velocity changes only gradually, we have two points ¢£ and ¤:£ . This source-receiver pair is linked by a reflected paraxial ray ¢£O¢¤£M¤:£ . According to ( jCervený, 1987; Schleicher et al., 2001), we can express for the 2-D case the transformation from the local 2-D Cartesian coordinate Ú system to the 2-D ray-centered coordiante Ú system at ¢Œ¤ (Figure A-2) by §1 #Û* Ü žIÝ Ü £ Ÿž (A-5) (A-6) Ÿ,/. (A-7) ž ,f. ¸ ,f. ,f. ¸ ¸ × £ @' In paraxial approximation, the curved surface can be expressed as a parabola. In the , this is representable as local 2-D coordinate system ¯ & · Û (A-8) Û´ ¯

Ã Ø Ì 0 0 Ì 4 0 à 0 G ' 4 ¯ à £ 0 4 0 0 ¯ à à 4 à à £ 0 ž à ž B » B » 4 à 33 where · is the surface's curvature at ¢Œ¤ (Schleicher et al., 2001). is expressed in terms of the NIP and N wavefront curvatures à à and £§¦©¨ The Ù matrix (Hubral, 1983) by £ (A-9) Ö ¯ Ö £§¦©¨ £ & · By substituting eqs. (A-6), (A-7) and the components of matrix Ù (eq. A-9) into eqs. (A-1) we obtain the components °(|¬ |¾ and ¿ of the matrix Ì given by eqs. (7). The matrix Ì also can now be defined in terms of the matrix Ù by Þ©ß a ¯ a 4 £§¦©¨ £§¦©¨ £§¦©¨ £ 4áà ¬ ° ¿ ¾ » B (A-10) » ¯ Inserting the elements of the propagator matrix Ù , we obtain » ž ­…â Ù 0 ­…â 4 > ¬ ° ¿ ¾ » B (A-11) Ö ­…â » ž ­…â Ö ¯ thus proving the validity of equations (A-1). a ¯ a 4 » ¯ 2h Xg Xs SG m G’ curved surface normal ray S’ paraxial ray . R R’ reflector Figure A-1: Ray diagram for a paraxial ray in the vicinity of a normal ray in a 2D laterally inhomogeneous medium.

Elements of the surface-to-surface propagator matrix Ì<br />

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32<br />

APPENDIX A<br />

Following (Hubral et al., 1992a; jCervený, 1999; Schleicher et al., 2001), we can express<br />

for the 2-D case the ÍÀÎ submatrices ÏÑÐ<br />

Ð of the ÈÕÀÂÈ surfaceto-surface<br />

propagator Ì matrix<br />

1993) form by<br />

(Bortfeld, 1989; Hubral et al., 1992a; Schleicher et al.,<br />

¤Ò<br />

^Ó<br />

¤Ô<br />

(A-1)<br />

° Ö ¯<br />

'@Ö ˆ×<br />

(A-2)<br />

ˆ× £ka<br />

ž<br />

× £ Ö ¯<br />

× £ Ö ˆ×<br />

(A-3)<br />

¾ ž<br />

žI'<br />

£ia<br />

ž<br />

× £ Ö <br />

(A-4)<br />

£ a ¯<br />

¿ <br />

propagator<br />

a ¯ a Ö ¯ where Ö and are the scalar elements of the Ø so-called<br />

matrix (Popov and Pjsenjc´ffk, 1978; jCervený, 1985; Hubral et al., 1992a). The matrix<br />

is defined in a Cartesian coordinate system and the propagator matrix Ù is defined<br />

Ì<br />

in a ray centered coordinate system ( jCervený, 1987).<br />

We assume a 2-D model (Figures 6.1 and 6.2) with a curved measurement surface.<br />

We have a source point ¢ coinciding with the receiver point ¤ . In the paraxial vicinity<br />

of the normal ray surface location ¢Œ¤ , where the medium velocity changes only<br />

gradually, we have two points ¢£ and ¤:£ . This source-receiver pair is linked by a<br />

reflected paraxial ray ¢£O¢¤£M¤:£ . According to ( jCervený, 1987; Schleicher et al., 2001),<br />

we can express for the 2-D case the transformation from the local 2-D Cartesian<br />

coordinate Ú system to the 2-D ray-centered coordiante Ú system<br />

at ¢Œ¤<br />

(Figure A-2) by<br />

§1<br />

#Û*<br />

Ü žIÝ Ü £<br />

Ÿž<br />

(A-5)<br />

(A-6)<br />

Ÿ,/.<br />

(A-7)<br />

ž ,f.<br />

¸<br />

,f.<br />

,f.<br />

¸<br />

¸<br />

× £<br />

@'<br />

In paraxial approximation, the curved surface can be expressed as a parabola. In the<br />

, this is representable as<br />

local 2-D coordinate system ¯<br />

& ·<br />

Û<br />

(A-8)<br />

Û´<br />

<br />

¯

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