Bimorph

About: Bimorph is a research topic. Over the lifetime, 3339 publications have been published within this topic receiving 51880 citations.

In situ beamline analysis and correction of active optics

Abstract: At the Diamond Light Source, pencil-beam measurements have enabled long-wavelength slope errors on X-ray mirror surfaces to be examined under ultra-high vacuum and beamline mounting without the need to remove the mirror from the beamline. For an active mirror an automated procedure has been implemented to calculate the actuator settings that optimize its figure. More recently, this in situ pencil-beam method has been applied to additional uses for which ex situ measurements would be inconvenient or simply impossible. First, it has been used to check the stability of the slope errors of several bimorph mirrors at intervals of several weeks or months. Then, it also proved useful for the adjustment of bender and sag compensation actuators on mechanically bent mirrors. Fits to the bending of ideal beams have been performed on the slope errors of a mechanically bent mirror in order to distinguish curvatures introduced by the bending actuators from gravitational distortion. Application of the optimization procedure to another mechanically bent mirror led to an improvement of its sag compensation mechanism.

Micro-mirrors with variable focal length, and optical components comprising micro-mirrors

Abstract: A micro-mirror comprises a membrane of a dielectric polymer layer between two metal layers for supplying a high frequency ac voltage thereto for dielectric heating of the membrane, and a further polymer layer adjacent to and forming a bimorph with the second metal layer, the membrane being supported around its periphery so that the membrane produces a mirror with a curvature, and hence a focal length, dependent upon the heating. Such micro-mirrors are useful in optical signal paths in optical components, including optical receivers and variable attenuators. A detected optical signal can be used in a feedback control path to control a high frequency ac voltage source connected to the two metal layers, and hence the focal length of the micro-mirror.

Modeling and experimental verification of an impact-based piezoelectric vibration energy harvester with a rolling proof mass

Abstract: Impact-based vibration energy harvesters (VEHs) with a rolling proof mass are promising candidates for scavenging ambient low-level, broadband, and low-frequency vibration energy. This paper derives the mathematical model of a VEH with two piezoelectric cantilevers symmetrically located at two open ends of a guiding channel with a rolling steel ball inside as the proof mass. The model includes the equation of motion and coupled electrical circuit equation of the bimorphs under base excitation, the equations of motion of the rolling proof mass under base excitation, and the collision equations between the bimorphs and the proof mass. Simulation results show that the scavenging efficiency of low-level vibration can be improved by introducing the rolling proof mass. The numerical results agree well with the experiments when the harvester prototype is horizontally fixed on the base. Under the base excitation of 1 g(=9.8 m/s 2 ), the maximum output power of one bimorph is about 511 μW at 18.4 Hz.

Integrated self-assembling and holding technique applied to a 3-D MEMS variable optical attenuator

Abstract: The application of polysilicon/gold bimorph stress-induced curved beams for three-dimensional self-assembly of MEMS devices is reported. The mechanical principle behind this self-assembling procedure is presented and comparison with current assembling methods are made. With this self-assembling technique, no postprocessing is required. A free-space optical MEMS device in the form of a variable optical attenuator (VOA) has been fabricated and self-assembled using this technique. The angular elevation of the self-assembled structures and the attenuation characteristics of the optical MEMS device are reported. The VOA has a measured dynamic attenuation range of 44 dB at 1.55 /spl mu/m optical wavelength. The bending of the bimorph beams is also temperature controllable, and the thermal behavior of the beams is also reported.

Development and characterization of single wall carbon nanotube-Nafion composite actuators

Abstract: The development and characterization of thin film polymeric actuators has been performed for single wall carbon nanotube (SWNT)–Nafion composite systems. Previous work in our laboratory illustrated that incorporation of highly conductive SWNTs into an ionomeric matrix promoted an actuation response by enhancing the electro-osmotic effect at relatively low doping levels, ∼0.1% (w/w). Further investigation has shown the effects of frequency and applied voltage on the composite bimorph actuator systems. The results indicate a displacement response that is linearly dependent on voltage and inverse to frequency.