For in-line Fraunhofer holography in cylindrical tunnels, two methods are proposed to neutralize the window curvature effects. One is to modify the usually flat outer surfaces of the window into curved surfaces parallel to the original cylindrical direction; the desired outer curvature is determined in this paper. The second method proposes two separate parallel cylindrical lenses (one on each side) for zero net power. The desired lens parameters are determined in terms of the known physical quantities.
C. S. Vikram,
M. L. Billet,
"Fraunhofer Holography In Cylindrical Tunnels: Neutralizing Window Curvature Effects," Optical Engineering 25(1), 251189 (1 January 1986). https://doi.org/10.1117/12.7973799