Design and development of a freeform active mirror for an astronomy application

Abstract

International audienceThe advent of extremely large telescopes will bring unprecedented light-collecting power and spatial resolution, but it will also lead to a significant increase in the size and complexity of focal-plane instruments. The use of freeform mirrors could drastically reduce the number of components in optical systems. Currently, manufacturing issues limit the common use of freeform mirrors at short wavelengths. This article outlines the use of freeform mirrors in astronomical instruments with a description of two efficient freeform optical systems. A new manufacturing method is presented which seeks to overcome the manufacturing issues through hydroforming of thin polished substrates. A specific design of an active array is detailed, which will compensate for residual manufacturing errors, thermoelastic deformation, and gravity-induced errors during observations. The combined hydroformed mirror and the active array comprise the Freeform Active Mirror Experiment, which will produce an accurate, compact, and stable freeform optics dedicated to visible and near-infrared observations. (C) 2014 Society of Photo-Optical Instrumentation Engineers (SPIE

Use of 3D printing in astronomical mirror fabrication

“…The objective is to create a very thin deformable mirror with embedded actuator supports. In the continuity of Freeform Active Mirror Experiment (FAME), 4 the idea is to build a very thin deformable mirror with integrated actuators supports to remove of the assembly steps, as bonding the actuator supports after polishing degraded the surface quality. To expand the study, we are interested in other actuator patterns with thin optical surface that could be good candidate to be printed.…”

Adaptive Spiral Tool Path Generation for Diamond Turning of Large Aperture Freeform Optics

“…In general, the results of a 3D design method are nonrotational, nonlinear asymmetric surfaces, known as freeform surfaces. With the development of 3D optical design methods, large aperture freeform optics are increasingly used in both non-imaging and imaging optical systems due to its capacity of improving optical performance [ 3 , 4 , 5 , 6 ]. There are three ultra-precision machining processes, namely fast tool servo (FTS), slow tool servo (STS) and diamond milling frequently used to produce optical freeform surfaces.…”

Space Telescope Designed for Accurate Measurements

“…Obviously, in these conditions it is not easy to find a suitable solution both in the class of axisymmetrical wide-field systems (Terebizh 2011(Terebizh , 2016) and among off-axial systems with aspheric and freeform optical surfaces (Hugot et al 2014;Buffington 1998;Singaravelu and Cabanac 2014;Challita et al 2014). In this note, we consider a 400-mm model, which is a modified version of the folded aplanatic Gregory telescope 1 provided by a two-lens corrector protected from cosmic particles.…”