Metrology of freeform shaped parts

The need for dimensional micro and nano metrology is evident, and as critical dimensions are scaled down and geometrical complexity of objects is increased, the available technologies appear not sufficient. Major research and development efforts have to be undertaken in order to answer these challenges. The developments have to include new measuring principles and instrumentation, tolerancing rules and procedures as well as traceability and calibration. The current paper describes issues and challenges in dimensional micro and nano metrology by reviewing typical measurement tasks and available instrumentation. Traceability and calibration issues are discussed subsequently. Finally needs and gaps are identified based on these observations.

Dimensional micro and nano metrology

From the ardent bucklers used during the Syracuse battle to set fire to Romans’ ships to more contemporary piezoelectric
deformable mirrors widely used in astronomy, from very large voice coil deformable mirrors considered in future
Extremely Large Telescopes to very small and compact ones embedded in Multi Object Adaptive Optics systems, this
paper aims at giving an overview of Deformable Mirror technology for Adaptive Optics and Astronomy.
First the main drivers for the design of Deformable Mirrors are recalled, not only related to atmospheric aberration
compensation but also to environmental conditions or mechanical constraints. Then the different technologies available
today for the manufacturing of Deformable Mirrors will be described, pros and cons analyzed. A review of the
Companies and Institutes with capabilities in delivering Deformable Mirrors to astronomers will be presented, as well as
lessons learned from the past 25 years of technological development and operation on sky. In conclusion, perspective
will be tentatively drawn for what regards the future of Deformable Mirror technology for Astronomy.

/pdf/overview-of-deformable-mirror-technologies-for-adaptive-j8uqtes2ke.pdf

Overview of deformable mirror technologies for adaptive optics and astronomy

http://www.mate.tue.nl/mate/pdfs/1591.pdf

Development of a Silicon-based Nanoprobe System for 3-D Measurements

• A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers.

/pdf/development-of-high-precision-mechanical-probes-for-4sgyw7291t.pdf

Development of high precision mechanical probes for coordinate measuring machines

Conventional Minimally Invasive Surgery (MIS) is performed with long and slender camera and instruments through at least three small incisions However, it generally provides the surgeon with an uncomfortable body posture, limited force feedback and unnatural eye-hand-coordination A master-slave system with force feedback is being developed, since such a system can overcome the inconveniences of MIS This paper is about the design of the master and the slave

http://www.mate.tue.nl/mate/pdfs/10805.pdf

Design of a minimally invasive surgical teleoperated master-slave system with haptic feedback

A displacement generator is realized which enables the calibration of a wide variety of displacement-measuring probes, such as probes of roundness testers, roughness testers and stand-alone type scanning probe microscopes (SPMs), in the range of with a standard uncertainty below 1 nm. A digital piezo translator (DPT) drives a flat mirror which serves as the calibration platform. This mirror is locked to an elastic, hysteresis-free, monolithic parallel guide. Calibration of the platform displacement is carried out by various methods including tunable and stabilized lasers, Fabry-Perot interferometry and laser interferometry. The system is calibrated with a standard uncertainty of about 0.1 nm using three independent methods. As an example the calibration of an SPM using generated steps is shown.

Design and calibration of a parallel-moving displacement generator for nano-metrology

A new prototype adaptive deformable mirror for future AO-systems is presented that consists of a thin continuous membrane on which push-pull actuators impose out-of-plane displacements. Each actuator has ±10?m stroke, nanometer resolution and only mW’s heat dissipation. The mirror’s modular design makes the mechanics, electronics and control system extendable towards large numbers of actuators. Models of the mirror are derived that are validated using influence and transfer function measurements. First results of a prototype with 427 actuators are also presented.

/pdf/validation-of-a-new-adaptive-deformable-mirror-concept-3ufre2qbze.pdf

Validation of a new adaptive deformable mirror concept

Future large optical telescopes require adaptive optics (AO) systems whose deformable mirrors (DM) have ever more degrees of freedom. This paper describes advances that are made in a project aimed to design a new AO system that is extendible to meet tomorrow's specifications. Advances on the mechanical design are reported in a companion paper [6272-75], whereas this paper discusses the controller design aspects. The numerical complexity of controller designs often used for AO scales with the fourth power in the diameter of the telescope's primary mirror. For future large telescopes this will undoubtedly become a critical aspect. This paper demonstrates the feasibility of solving this issue with a distributed controller design. A distributed framework will be introduced in which each actuator has a separate processor that can communicate with a few direct neighbors. First, the DM will be modeled and shown to be compatible with the framework. Then, adaptive turbulence models that fit the framework will be shown to adequately capture the spatio-temporal behavior of the atmospheric disturbance, constituting a first step towards a distributed optimal control. Finally, the wavefront reconstruction step is fitted into the distributed framework such that the computational complexity for each processor increases only linearly with the telescope diameter.

/pdf/distributed-control-in-adaptive-optics-deformable-mirror-and-476rgvcgai.pdf

Distributed control in adaptive optics: Deformable mirror and turbulence modeling

With the future growing size of telescopes, new, high-resolution, affordable wavefront corrector technology with low power dissipation is needed. A new adaptive deformable mirror concept is presented, to meet such requirements. The adaptive mirror consists of a thin (30-50 μm), highly reflective, deformable membrane. An actuator grid with thousands of actuators is designed which push and pull at the membrane’s surface, free from pinning and piston effects. The membrane and the actuator grid are supported by an optimized light and stiff honeycomb sandwich structure. This mechanically stable and thermally insensitive support structure provides a stiff reference plane for the actuators. The design is extendable up to several hundreds of mm's. Low-voltage electro-magnetic actuators have been designed. These highly linear actuators can provide a stroke of 15 micrometers. The design allows for a stroke difference between adjacent actuators larger than 1 micron. The actuator grid has a layer-based design; these layers extend over a large numbers of actuators. The current actuator design allows for actuator pitches of 3 mm or more. Actuation is free from play, friction and mechanical hysteresis and therefore has a high positioning resolution and is highly repeatable. The lowest mechanical resonance frequency is in the range of kHz so a high control bandwidth can be achieved. The power dissipation in the actuator grid is in the order of milliwatts per actuator. Because of this low power dissipation active cooling is not required. A first prototype is currently being developed. Prototypes will be developed with increasing number of actuators.

Nick Rosielle

Papers

Design of a minimally invasive surgical teleoperated master-slave system with haptic feedback

Design and calibration of a parallel-moving displacement generator for nano-metrology

Validation of a new adaptive deformable mirror concept

Distributed control in adaptive optics: Deformable mirror and turbulence modeling

Large adaptive deformable membrane mirror with high actuator density