  The ingot WFS is a new kind of wavefront sensor specifically designed to deal
with the elongation of LGS reference sources on ELT-class telescopes. Like the
pyramid, it belongs to the family of pupil plane wavefront sensors and can be
considered as a generalization of the pyramid WFS for extended,
three-dimensional elongated sources. The current design uses a simple,
reflective roof-shaped prism to split the light into three pupils that are used
to retrieve the wavefront shape. A test-bench has been realized at the
INAF-Padova laboratories to test the alignment and functioning of the ingot.
The bench is equipped with a deformable lens, conjugated to the pupil plane,
able to apply low-order aberrations and with a hexapod for the precise
alignment of the ingot prism. In this work we present a robust and fully
automated Python-code alignment procedure, which is able, by using the optical
feedback from the I-WFS, to adjust its 6-degrees of freedom. Moreover, we
report on the tests conducted with the deformable lens to characterize the
ingot WFS response to low-order aberrations in terms of sensitivity and
linearity. The results are used as a comparison for simulations to validate the
ray-tracing modeling approach with the future goal of optimizing the procedure
adopted for signal calculation and phase retrieval.
