Linearization of the response of a 91-actuator magnetic liquid deformable mirror

Abstract

Abstract:We present the experimental performance of a 91-actuator deformable mirror made of a magnetic liquid (ferrofluid) using a new technique that linearizes the response of the mirror by superposing a uniform magnetic field to the one produced by the actuators. We demonstrate linear driving of the mirror using influence functions, measured with a Fizeau interferometer, by producing the first 36 Zernikes polynomials. Based on our measurements, we predict achievable mean PV wavefront amplitudes of up to 30 µm having RMS residuals of λ/10 at 632.8 nm. Linear combination of Zernikes and over-time repeatability are also demonstrated.

Aluminum‐coated elastomer thin films for the fabrication of a ferrofluidic deformable mirror

“…Deformation measurements were performed by placing the aluminum container directly on an array of 2.8 mm electromagnetic coils (actuators). As described elsewhere, the mirror assembly is placed in a Maxwell coil to produce a uniform steady‐state magnetic field . The mirror surface is deformed by modification of the magnetic fields through the selective activation of the actuator coils.…”

Dynamic response of ferrofluidic deformable mirrors using elastomer membrane and overdrive techniques

“…During the past few years, our team has carried out research in adaptive optics using deformable ferrofluidic mirrors [1][2][3][4][5]. Although the demonstration of a novel type of deformable mirror that can generate high amplitude deformations with RMS residuals of λ/10 was made, there were issues that needed to be addressed.…”

Modal dynamics of magnetic-liquid deformable mirrors

“…Up until recently, this vectorial attribute proscribed the use of standard control algorithms in which the surface of the deformable mirror is predicted through the linear addition of the actuators' influence functions. A way to counter this problem was introduced in [3] and experimentally validated in [4]. The linear superposition behavior of the influence functions is achieved by using a large and uniform magnetic field that is superimposed to the magnetic field produced by the MLDM actuators.…”