For a long time it has been
known that in a Euclidean space one can reflect a minimal surface across
a part of its boundary if the boundary contains a line segment, or if the
minimal surface meets a plane orthogonally along the boundary. The proof
of this fact makes use of H. A. Schwarz’s reflection principle for harmonic
functions.
In this paper we show that a minimal surface, as a conformal and harmonic map
from a Riemann surface into R3, can also be reflected analytically if it meets a plane
at a constant angle.