Thesis (Ph. D.)--University of Rochester. The Institute of Optics, 2020.
This thesis presents advances in the application of phase retrieval techniques to
optical metrology of spherical and freeform surfaces.
We explore metrology configurations using transverse translation-diverse
phase retrieval (TTDPR), in which translating subaperture illumination is
projected on the test surface. The wavefront aberration, and from it surface error,
can be reconstructed from measured reflected intensities. TTDPR is advantageous
for freeform surface metrology due to its relatively simple hardware requirements
and demonstrated accuracy in other fields.
Through simulations we probe TTDPR performance as a function of various
parameters including illumination beam softness, detector signal-to-noise ratio
and position uncertainty of the illumination.
We report on the laboratory measurement of a concave spherical test surface
using TTDPR, which agrees with an interferometric measurement to 0:006λ
root-mean-square (RMS) with certain terms removed.
We report on measurements of a concave freeform using TTDPR. Freeform
surface reconstructions from two disjoint datasets agree to 13 nm RMS, or 0:02λ RMS at λ = 632:8nm.
Next we explore configurations suitable for metrology of convex surfaces. We
explore a configuration using converging source illumination and a moving test
surface. We discuss a suitable algorithm, prescription retrieval, with which we
directly reconstruct surface prescription terms from measured intensities using
combined ray-tracing and diffraction modeling. A prescription retrieval algorithm
is demonstrated through simulation and ultimately a convex surface measurement
using the technique is demonstrated.
