jeudi 16 février 2023
The source’s light is brought from the source unit to the bench by a fiber which exit in the first focal plane (FP1). The light is then reflected on the first off axis parabola (OAP-1) then sent of the tip-tilt mirror. This mirror is located 20 mm before the first pupil plane (PP1), where 8.3 mm circular obstructed and unobstructed pupils can be placed. After this pupil, the beam encounters the first deformable mirror (DM-1), then the second off axis parabola (OAP-2). A second deformable mirror (DM-2) can be inserted insted of a flat mirror in a diverging beam right after (FP2) which is empty for the moment. The light is reflected on OAP 3 then on the third deformable mirror (DM-3), located in a second pupil plane (PP2). We focalize the light, using OAP 3 again, on the coronagraphic mask in focal plane (FP3). Finally, the beam is collimated to go through the Lyot pupil in pupil plane (PP3). A last OAP and a couple of plan mirrors are used to focalized the beam on either an Andor NEO detector or a visitor focal plane.
A tubulence wheel can be inserted at the entrance of the bench to simulate dynamical aberrations on the bench. The actual wheel is simulating the residual aberration on a SPHERE-like instrument
A low-order wavefront sensor uses the light reflected by the Lyot stop to measure the tip-tilt of the beam. Compensation of the tip-tilt errors is done using the Tip-Tilt mirror at a frequency >100Hz.
