In wave-optical engineering the propagation of light through optical elements can be simulated using different physical approximations. Independent of the used approximation it is necessary to have full access to the complete wave information (for example the amplitude, phase and polarization) everywhere in the optical system. This means if geometric optics approximation (ray tracing) should be used in wave-optical engineering it must be possible to reconstruct the complex amplitude from the rays after a ray tracing step. Therefore it is also necessary to convert the complex amplitude of a wave into rays before the beginning of the ray tracing. For the reconstruction of the complex amplitude typically interpolation techniques must be used. To make ray tracing in wave-optical engineering practicable efficient interpolation techniques are required. The authors will discuss the conversion of a complex amplitude into rays and vise versa. The use of geometric optics approximation together with other approximations of the wave propagations for the analysis and the design of optical systems will be demonstrated.