UNDEVIATED AND DEVIATED WAVES 



distances be measured in wavelengths and let 



sin ^0 = Po- 



43 



(6.1) 



The optical path difference along d is then 27rno?/oPo radians, where no 

 is the refractive index of the object space. The wave disturbance in- 

 cident at I/O = yo is therefore advanced by 2TrnoyoPo radians with respect 

 to the wave disturbance incident at yo = 0. In accordance with the 



Fig. 11.13. Reorientation of the Xo direction so that the incident wave front W 

 intersects the A'o axis. The azimuthal angle ao is then zero, ge^-^ is a complex num- 

 ber which specifies the amplitude and phase transmission of the particle relative to 



the surround. 



convention adopted with respect to the phase factor p"^"* in Eq. 5.2, 

 is negative when it represents an advance in phase. Hence 



= — 27r/)o2/oPo- (6.2) 



If we now let w denote the amplitude and phase of the incident wave 

 disturbance which is in actual contact with the object plane, 



We shall refer henceforth to w as the incident wave. It is to be dis- 

 tinguished from the inclined wave front W which we shall henceforth 

 ignore. 



Several advantages are gained without any essential loss of generality 

 by representing the amplitude and phase transmission of the medium 

 surrounding the particle by the number unity, provided that the sur- 



