  The increase in gravitational wave (GW) events has allowed receiving strong
lensing image pairs of GWs. However, the wave effect (diffraction and
interference) due to the microlens field contaminates the parameter estimation
of the image pair, which may lead to a misjudgment of strong lensing signals.
To quantify the influence of the microlens field, researchers need a large
sample of statistical research. Nevertheless, due to the oscillation
characteristic, the Fresnel-Kirchhoff diffraction integral's computational time
hinders this aspect's study. Although many algorithms are available, most
cannot be well applied to the case where the microlens field is embedded in
galaxy/galaxy clusters. This work proposes a faster and more accurate algorithm
for studying the wave optics effect of microlenses embedded in different types
of strong lensing images. Additionally, we provide a quantitative estimation
criterion for the lens plane boundary for the Fresnel-Kirchhoff diffraction
integral. This algorithm can significantly facilitate the study of wave optics,
particularly in the case of microlens fields embedded in galaxy/galaxy
clusters.
