Publications de Roland Andreas Bitterli

La géométrie du tourbillon

Simon Nessim Henein, Roland Andreas Bitterli, Quentin Gubler, Ilan Vardi, Patrick Robert Flückiger

À l'origine, le but du tourbillon était d'améliorer la chronométrie d'une montre de poche en moyennant ses positions verticales. Avec I'avènement de la montre-bracelet, le tourbillon est prisé plus pour la prouesse technique de sa réalisation que pour sa f ...

Société Suisse de Chronométrie2021

Echappements à impulsion virtuelle

Simon Nessim Henein, Roland Andreas Bitterli, Ilan Vardi, Etienne Frédéric Gabriel Thalmann, Laura Marie Lucie Convert

L’échappement à détente est reconnu pour sa performance chronométrique, mais il n’est pas sécurisé pour la montre-bracelet. Plusieurs échappements ont été proposés pour adapter cet échappement à la montre, dont l’échappement Robin récemment sécurisé par Au ...

2018

Theory and design of spherical oscillator mechanisms

Simon Nessim Henein, Roland Andreas Bitterli, Ilan Vardi, Lennart Rubbert, Mohammad Hussein Kahrobaiyan, Nicolas Ferrier, Billy Nussbaumer

In previous work, we showed that two degree of freedom oscillators can be advantageously applied to horological time bases since they can be used to eliminate the escapement mechanism. We subsequently examined planar two degree of freedom oscillators based ...

2018

Refraction limit of miniaturized optical systems: a ball-lens example

Hans Peter Herzig, Roland Andreas Bitterli, Toralf Scharf, Wilfried Noell, Myun Sik Kim

We study experimentally and theoretically the electromagnetic field in amplitude and phase behind ball-lenses across a wide range of diameters, ranging from a millimeter scale down to a micrometer. Based on the observation, we study the transition between ...

Optical Society of America2016

Isotropic springs based on parallel flexure stages

Simon Nessim Henein, Roland Andreas Bitterli, Ilan Vardi, Lennart Rubbert, Nicolas Ferrier, Sebastian Krzysztof Fifanski

We define isotropic springs to be central springs having the same restoring force in all directions. In previous work, we showed that isotropic springs can be advantageously applied to horological time bases since they can be used to eliminate the escapeme ...

2015

On Micro Optical Elements for Efficient Light Diffusion

Roland Andreas Bitterli

Efficient light management is one of the key issues in modern energy conversion systems, be it to collect optical power or to redistribute light generated by high power light emitters. This thesis touches mainly on the subject of efficient light redistribu ...

EPFL2013

Fabrication and characterization of linear diffusers based on concave micro lens arrays

Nico de Rooij, Hans Peter Herzig, Roland Andreas Bitterli, Toralf Scharf, Wilfried Noell

We present a new approach of beam homogenizing elements based on a statistical array of concave cylindrical microlens arrays. Those elements are used to diffuse light in only one direction and can be employed together with fly’s eye condensers to generate ...

Optical Society of America2010

Fabrication and Characterization of 1-D diffusing elements

Hans Peter Herzig, Roland Andreas Bitterli, Toralf Scharf, Myun Sik Kim

Certain high power laser applications require thin homogeneous laser lines. In this paper we describe the concept, fabrication and characterization of a 1-D diffuser that generates such a line. The device is based on an array of concave cylinder lenses wit ...

2009

Dynamic array spot shaping for laser micro machining

Roland Andreas Bitterli, Jonathan Masson, Wilfried Noell, Toralf Scharf

2009

Multifunctional Micro-Optical Elements for Laser Beam Homogenizing and Beam Shaping

Nico de Rooij, Hans Peter Herzig, Roland Andreas Bitterli, Toralf Scharf

2008