Вращение микротубины некольцевым световым пучком, сформированным вихревым аксиконом

Рассмотрена возможность использования сложного вихревого светового пучка с топологическими зарядами 2 и 5 для вращения микромеханического элемента (микротурбины). Представлены результаты натурного эксперимента по оптическому вращения микротурбины специальной формы. Проведена оценка момента силы, действующей на микротурбину

Proceedings of the 2018 Canadian Society for Mechanical Engineering (CSME) International Congress

Published proceedings of the 2018 Canadian Society for Mechanical Engineering (CSME) International Congress, hosted by York University, 27-30 May 2018

The development of optical nanomachines for studying molecules : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Mechatronics Engineering at Massey University, Palmerston North, New Zealand

Chapter 3 is ©2020 IEEE. Accepted manuscript is reprinted, with permission, from 2020 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM). Chapter 5 is ©2022 IEEE. Accepted manuscript is reprinted, with permission, from 2022 International Conference on Manipulation, Automation and Robotics at Small Scales (MARSS).Optical tweezers have been used for a number of applications since their invention by Arthur Ashkin in 1986, and are particularly useful for biological and biophysical studies due to their exceptionally high spatial and force-based resolution. The same intense laser focus that allows light to be used as a tool for micro-nanoscale manipulation also has the potential to damage the objects being studied, and the extremely high force resolution is coupled with the limitation of very low forces. There is potential to overcome these drawbacks of optical manipulation through making use of another laser based technique: two-photon absorption polymerisation (TPAP). This thesis has brought these together to demonstrate the uses of optical nanomachines as helpful tools for optical tweezer studies. The project was highly interdisciplinary, concerning the intersection of optical trapping, 3D micromachine design and development, and DNA stretching. The thesis was based around the strategy of first developing microrobots and demonstrating their manipulation using optical tweezers, then adjusting the design for specific applications. Microlevers were developed for lever-assisted DNA stretching and amplification of optical forces. The influence of design features and TPAP parameters on microlever functionality was investigated; particularly the influence of overlapping area and presence of supports, and the effects of differently shaped "trapping handles". These features were important as lever functionality was tested in solutions of different ionic strength, and stable trapping of the levers was required for force amplification. DNA stretching was chosen as a target application for distanced-application of optical forces due to its status as a well-known and characterised example of single-molecule studies with optical tweezers. Amplification of optical forces was also seen as an application that could demonstrate the utility of optical micromachines, and microlevers with a 2:1 lever arm ratio were developed to produce consistent, two-fold amplification of optical forces, in a first for unsupported, pin-jointed optical microrobotics. It is hoped that in the future fully-remote, micromachine-assisted studies will extend optical tweezer studies of laser-sensitive subjects, as well as increasing the forces that can be applied, and the results obtained in this thesis are encouraging. All in all, the thesis confirms the potential of optical micromachines for aiding studies using optical tweezers, and demonstrates concrete progress in both design and application

Brownian motors: noisy transport far from equilibrium

Transport phenomena in spatially periodic systems far from thermal equilibrium are considered. The main emphasize is put on directed transport in so-called Brownian motors (ratchets), i.e. a dissipative dynamics in the presence of thermal noise and some prototypical perturbation that drives the system out of equilibrium without introducing a priori an obvious bias into one or the other direction of motion. Symmetry conditions for the appearance (or not) of directed current, its inversion upon variation of certain parameters, and quantitative theoretical predictions for specific models are reviewed as well as a wide variety of experimental realizations and biological applications, especially the modeling of molecular motors. Extensions include quantum mechanical and collective effects, Hamiltonian ratchets, the influence of spatial disorder, and diffusive transport.Comment: Revised version (Aug. 2001), accepted for publication in Physics Report

Rotational Efficiency of Photo-Driven Archimedes Screws for Micropumps

In this study, we characterized the rotational efficiency of the photo-driven Archimedes screw. The micron-sized Archimedes screws were fabricated using the two-photon polymerization technique. Free-floating screws trapped by optical tweezers align in the laser irradiation direction and rotate spontaneously. The influences of the screw pitch and the number of screw blades have been investigated in our previous studies. In this paper, the blade thickness and the central rod of the screw were further investigated. The experimental results indicate that the blade thickness contributes to rotational stability, but not to rotational speed, and that the central rod stabilizes the rotating screw but is not conducive to rotational speed. Finally, the effect of the numerical aperture (NA) of the optical tweezers was investigated through a demonstration. The NA is inversely proportional to the rotational speed

Thermo-mechanical design, realization and testing of screen-printed deformable mirrors

Die primäre Zielstellung dieser Dissertation ist die Entwicklung ungekühlter, unimorph deformierbarer Spiegel (DM) zum Ausgleich thermischer Linsen in Hochleistungslasersystemen. Die sekundäre Zielstellung ist die Entwicklung eines Herstellungsprozesses für DM, der hauptsächlich auf Waferleveltechnologien beruht und somit manuelle Prozesse reduziert.Der DM besteht aus einem Spiegelsubstrat auf dessen Rückseite eine piezoelektrische Schicht zwischen zwei Elektroden aufgebracht ist. Diese Art von Spiegeln wurde bereits erfolgreich in Hochleistungslasersystemen eingesetzt. Eine weitere Erhöhung der Laserleistungsdichte erfordert jedoch neue thermische Kompensationstechniken, bei der die Spiegelperformance nicht durch Temperaturschwankungen in der Spiegelbaugruppe vermindert wird.Ein hierfür entwickeltes Mehrlagendesign integriert mehrere Schichten in den Spiegelaufbau, dessen thermo-mechanische Parameter sich vom Substrat und der piezoelektrischen Schicht unterscheiden. Mittels analytischen Methoden und der Methode der finiten Elemente wurde eine Optimierung im Hinblick auf großen piezoelektrischen Hub und optimierte thermisch-induzierte Deformation durchgeführt. Diese wird entweder durch eine homogene Temperaturveränderung in der Spiegelmembran oder durch Absorption von Laserstrahlung generiert. Die dabei hervorgerufenen Veränderungen werden abhängig von Diskontinuitäten der piezoelektrischen Schicht, den mechanischen Randbedingungen, der spiegelnden Kupferschichtdicke und der Spiegelfassungsmaterialen simuliert.Ein aus sechs Arbeitsschritten bestehende Herstellungsprozess für DM mit siebgedruckter piezoelektrischer Aktorstruktur wurde entwickelt. Fünf Schritte sind davon auf Waferlevel prozessierbar. Einzig die Bearbeitung der Spiegelfläche mittels eines ultrapräzisen Drehprozesses ist keine Serienfertigung. Im Gegensatz zum Stand der Technik für DM ist die elektrische Verdrahtung der strukturierten Elektroden auch auf Waferlevel prozessierbar und das Spiegelsetup ist monolithisch.Thermisch induzierte Deformationen durch homogene Temperaturveränderung kann durch eine sog. zero deflection Konfiguration ausgeglichen werden. Laserinduzierte Deformationen werden mit gegenläufigen, thermisch homogen induzierten Deformationen kompensiert. Dieser Ansatz wird als Compound loading bezeichnet und in einem praktischen Spiegelaufbau umgesetzt. Im realisierten DM wird eine Deformation, induziert durch 1.3 W absorbierte Laserleistung, über eine homogene Temperaturerhöhung um 34 K kompensiert. Damit wird gezeigt, dass die entwickelten und vorwiegend mit parallelen Fertigungstechnologien hergestellten Spiegel für Hochleistungslaseranwendungen geeignet sind.Abstract: The primary objective of this thesis is the development of non-cooled deformable unimorph mirrors (DM) for thermal lensing compensation in high-power laser systems. The secondary objective is the development of a manufacturing regime that consists mainly of batch-fabrication and reduced manual processes. The DM consists of a mirror substrate with a piezoelectric layer sandwiched between two electrodes, bonded on the mirror’s rear surface. These types of mirror have been successfully integrated into high-power laser systems; however, further increase in laser power requires new thermal compensation techniques in which the DMs performance is not affected by temperature changes in the mirror assembly.To achieve this objective, a multi-layer design was studied. The multi-layer design integrates several layers with thermo-mechanical parameters that differ from the substrate and the active layer into the mirror set-up. Beginning with this set-up, an optimization is performed with regard to the required large piezoelectric stroke and low thermally-induced deflection by analytical and finite element modelling. The thermally-induced deflection of the multi-layer is distinguished by their source into homogeneous thermal loading and inhomogeneous laser loading. The mirror response upon piezoelectric activation and both thermal loadings was simulated with respect to piezoelectric layer discontinuity, different mechanical boundary conditions, reflective copper-layer thickness, and mirror mount materials.The manufacturing regime of screen-printed piezoelectric DM is developed. The manufacturing process comprises six steps out of which five are batch-fabrication techniques. The mirror surface finishing by means of an ultraprecise turning process alone does not involve batch fabrication. In contrast to state-of-the-art deformable mirror technologies, the electric wiring of the addressing electrodes of the deformable mirror is also batch-fabricated and the mirror set-up is monolithic.The thesis presents possible concepts to compensate for thermally-induced mirror deformation. Thermally-induced deformation by homogeneous loading is balanced by the zero deflection configuration of the multi-layer. The compensation for laser-induced deformation can be achieved by homogeneous thermal loading that can compensate as the deformation caused by the loading opposes the laser-induced deformation. This approach is referred to as compound loading, and it is investigated in a practical mirror set-up. Here, a 1.3-W absorbed laser power is compensated by a 34-K homogeneous loading. It is concluded that the developed and mainly batch-fabricated DM are suitable for high-power laser applications