  Wavefront sensors encode phase information of an incoming wavefront into an
intensity pattern that can be measured on a camera. Several kinds of wavefront
sensors (WFS) are used in astronomical adaptive optics. Amongst them,
Fourier-based wavefront sensors perform a filtering operation on the wavefront
in the focal plane. The most well known example of a WFS of this kind is the
Zernike wavefront sensor, and the pyramid wavefront sensor (PWFS) also belongs
to this class. Based on this same principle, new WFSs can be proposed such as
the n-faced pyramid (which ultimately becomes an axicone) or the flattened
pyramid, depending on whether the image formation is incoherent or coherent. In
order to test such novel concepts, the LOOPS adaptive optics testbed hosted at
the Laboratoire d'Astrophysique de Marseille has been upgraded by adding a
Spatial Light Modulator (SLM). This device, placed in a focal plane produces
high-definition phase masks that mimic otherwise bulk optic devices. In this
paper, we first present the optical design and upgrades made to the
experimental setup of the LOOPS bench. Then, we focus on the generation of the
phase masks with the SLM and the implications of having such a device in a
focal plane. Finally, we present the first closed-loop results in either static
or dynamic mode with different WFS applied on the SLM.
