LOOPS

Full testbed name

LAM-ONERA On-sky Pyramid Sensor

Managing institution

Laboratoire d'Astrophysique de Marseille (LAM) / ONERA

Main scientific focus

LOOPS is an adaptive optics facility based at LAM. It provides a calibrated environment for research and development on the Pyramid Wavefront Sensor (PWFS) and Fourier-based Wavefront Sensor (FWFS). Among the topics related to the PWFS, the optical gain variation or the development of new reconstructors are of particular interest.

Environment of the testbed

The LOOPS tesbed is located in a grey room at LAM. The temperature and humidity are not controlled. An enclosure is planned to be installed on the bench to prevent from dust and parasite light.

Key hardware items

The bench is composed of four paths:

• A classical pyramid path using a four-sided monolithic pyramid wavefront sensor. The four sub-pupils are then re-imaged on an OCAM2 camera.

• A Fourier-based warfront sensing path using a Spatial Light Modulator (SLM) to create any shape of focal phase mask and test new design of WFS. A second OCAM2 camera is used to measure the signal in the pupil plane.

• A Shack-Hartman path to provide a wavefront sensing reference in order to compare the results obtained with the two other WFS.

• An imaging path playing the role of the science camera where the closed-loop PSF is observed and the Sthrel ratio can be computed.

Current status

The bench is actually being re-aligned after not having been used for a while. A precise description of the bench (e.g. phase error at pupil planes, NCPA, Strehl ratio) will be presented in a paper in the months to come.