We describe an accurate technique for computing the diffraction
point-spread function for optical systems. The approach is based on
the combined method of ray tracing and diffraction, which implies that
the computation is accomplished in a two-step procedure. First, ray
tracing is employed to compute the wave-front error in a reference
plane on the image side of the system and to determine the shape of the
vignetted pupil. Next the Rayleigh–Sommerfeld diffraction theory,
combined with the Kirchhoff approximation and the
Stamnes–Spjelkavik–Pedersen method for numerical integration, is
applied to compute the field in the region of the image. The method
does not rely on small-angle approximations and works well for a pupil
of general shape. Both scalar and electromagnetic computations are
discussed and numerical results are presented.
© 1998 Optical Society of America
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