New high-density deformable mirrors for high-contrast imaging

Abstract

This paper presents a new architecture for deformable mirrors, suitable for adaptive optics (AO) observations. The performance of these systems directly depends on the density of actuators, which correct for wavefront errors. Therefore, deformable mirrors of large sizes are difficult to build because of the required number of actuators. Moreover, these actuators use either piezoelectric, magnetic, or electrostatic systems, which all suffer from nonlinear behavior (hysteresis). To solve these problems, we propose to use addressable vertical-cavity surface-emitting laser (VCSELs) systems, which move, through radiation pressure, a CVD-diamond membrane coated with an aluminum/gold thin film. The advantage of such a system is the high actuator density (16 384 on 41 mm 2 ) without hysteresis problems. This technology is therefore well-suited for the next generation of AO systems.

Instantaneous phase retrieval with the vector vortex coronagraph

“…On the other hand, we must modify the EFC algorithm with our formalism to increase speed-up and obtain a direct global electric field minimization problem on the entrance pupil plane. A previous paper (Riaud 2012) on a new deformable mirror architecture provides all mathematical tools to use this NZ theory in the speckle cancellation process. Finally, we notice that if the corrections are not exactly in the pupil plane, some Fresnel propagations occur and small corrections of the Fraunhofer diffraction are needed (see Appendix H for a complete mathematical demonstration).…”

“…-Light scattering in thick materials, ghost features: scattering limitation and ghost features of the proposed calibration analysis system are calculated directly with the scattering function (see the Appendix O) and the Zemax software. -Residual polarization ellipticity due to non-ideal retardation over the entire wavelength range: the quarter-wave plates were optimized Riaud (2003), and we obtained a plate thickness of 0.24104 mm and 0.30792 mm at 20 • C for the MgF 2 and the quartz material, respectively. These thicknesses must be controlled to 1 μm with a Babinet compensator and the plate temperature must be controlled to ±0.5 • C. The residual phase error becomes σ 2 = 0.021 radian for the entire spectral bandpass.…”

Review of high-contrast imaging systems for current and future ground-based and space-based telescopes III: technology opportunities and pathways

“…9 One issue with DMs with high actuator counts is cabling. This issue is solved by a "photonic DM", 10,11 which uses light to address the deformable phase-sheet to activate individual activators, see Fig. 1.…”

Electrical coupling analysis of 2D time-multiplexing memory actuators exhibiting asymmetric butterfly hysteresis

“…New solutions and technologies are developed for realising high actuator densities in DMs 3,4 as well as novel materials tested and manufactured [5][6][7][8] . A recently presented concept of a hysteretic deformable mirror (HDM) 9 for an exoplanetimaging space mission opens up the possibility of deploying an extremely dense actuator array where 2D memory piezoactuators are realized by placing a newly developed piezoelectric shape memory material between two orthogonal layers of electrodes as illustrated in Figure 1.…”