1,721,000 research outputs found
3D printed optics with nanometer scale surface roughness
No full textComplex optical devices including aspherical focusing mirrors, solar concentrator arrays, and immersion lenses were 3D printed using commercial technology and experimentally demonstrated by evaluating surface roughness and shape. The as-printed surfaces had surface roughness on the order of tens of microns. To improve this unacceptable surface quality for creating optics, a polymer smoothing technique was developed. Atomic force microscopy and optical profilometry showed that the smoothing technique reduced the surface roughness to a few nanometers, consistent with the requirements of high-quality optics, while tests of optical functionality demonstrated that the overall shapes were maintained so that near theoretically predicted operation was achieved. The optical surface smoothing technique is a promising approach towards using 3D printing as a flexible tool for prototyping and fabrication of miniaturized high-quality optics
Tunable optical transversal filters based on a Gires-Tournois interferometer with MEMS phase shifters
No full textWe present tunable optical filters based on a modified Gires-Tournois interferometer. The back reflection plane of the interferometer is replaced with a one-dimensional micromirror array for phase modulation. Using Gaussian beam optics, we show that the transfer function of the device has the form of the transversal filter in digital signal processing. The design and analysis techniques of conventional digital filters can, therefore, be adapted to tunable optical filters. Both the amplitude and phase of the transfer function can be controlled by reconfiguring the micromirrors. Application examples in dispersion compensation and variable bandwidth bandpass filtering are discussed and experimentally demonstrated
MEMS switchable WDM deinterleaver based on a Gires-Tournois interferometer
No full textWe have designed, implemented and characterized a switchable optical (de)interleaver based on a Gires-Tournois interferometer geometry. Less than 1 μm piston motion of the individual mirrors of the array is required for tuning of the center wavelength, and for switching of (de)interleaved output ports. The concept can be extended to more complex filtering functions with a variety of applications in optical communication and sensin
Vertical micromirror fabricated in (110) silicon device layer by combination of KOH and DRIE etch
No full textThis paper reports on a variable-bandwidth optical filter employing a free-space grating as a dispersive element, and a variable-aperture MEMS reflector that selects the passband. This design introduces negligible dispersion across the passband, and provides individual control of the center wavelength and the optical bandwidth, as required for optimization of high-speed optical communication systems. The variable-aperture MEMS reflectors are defined on the vertical sidewalls of silicon-on-insulator material to allow combination with silicon-optical-bench features for integration of fibers, lenses, and gratings
Variable bandwidth optical filters with vertical micromirrors and silicon optical bench alignment technology
No full textA variable bandwidth, flat-passband optical filter based on a variable-aperture MEMS reflector was demonstrated. The filter is compatible with silicon-optical-bench technology. The reflecting mirror surface was defined by KOH wet-etching that produced a surface roughness of < 20 nm over the mirror. The optical bandwidth of the optical filter is continuously tunable from 3.4 nm to 6.3 nm
Chip-scale high-speed Fourier-transform spectrometer based on a combination of a Michelson and a Fabry-Perot interferometer
No full textMicromirror-based scan range enhancement in Fourier-domain optical coherence tomography
No full textThis paper reports on a micromirror-based superresolution technique that can increase the depth scan range of Fourier-domain optical coherence tomography by improving the spectral resolution of grating-based spectrometers with pixelated image sensors. ? 2006 IEEE
Vertical Mirror Fabrication Combining KOH Etch and DRIE of (110) Silicon
No full textThis paper presents fabrication of MEMS-actuated optical-quality vertical mirrors as the key active optical components in a silicon optical bench (SOB) technology. The fabrication process is based on a combination of potassium hydroxide (KOH) etch and deep reactive ion etching (DRIE) of (110) SOI wafers. The process starts by creating optical-quality vertical surfaces by KOH etch, followed by an oxidation step to protect them. The patterned wafer is then etched by DRIE to define actuators. The process is designed to allow the KOH etch and DRIE to be independently optimized without compromising either while at the same time meeting the challenge of lithography on high-aspectratio structures. Three variations of the fabrication process are demonstrated, two that use double masking layers and one that uses a silicon masking layer. We demonstrate in-plane scanners and fast translational vertical mirrors fabricated using these processes. In addition, we propose extensions of the fabrication process to account for DRIE aspect-ratio limitations. Mask layouts of key SOB building blocks, including vertical mirrors, beam splitters, and parallel-plate actuators, are also presented. [2008-0146
Single-crystalline silicon micromirrors actuated by self-aligned vertical electrostatic combdrives with piston-motion and rotation capability
No full textWe present micromirrors actuated by self-aligned, high aspect ratio, vertical electrostatic combdrives with multi-level electrical isolation that allows bi-directional and dual-mode (independent rotation and piston motion) operation. The fabrication process, which requires only front-side processing, is based on self-aligned deep-reactive ion etching (DRIE) of silicon-on-insulator (SOI) wafers with two device layers. The two oxide layers between the device layers provide electrode isolation and etch stops for thickness control. Self-alignment of electrostatic combs in the two device layers is accomplished by creating masking features in the upper layer that are transferred into the lower layer. The masking features are typically removed, but in some cases they remain as an integral part of the completed device. SEM pictures show perfectly aligned vertical combteeth both with and without removal of the masking features. We demonstrate micromirrors of this type with +/-9degrees of optical scanning and 7.5 mum of piston motion under static actuation. Micromirrors designed for resonant scanning have optical scan angles up to +/-25degrees at 13.5 kHz. (C) 2003 Elsevier B.V. All rights reserved
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