A confocal laser displacement sensor using a micro-machined varifocal mirror is reported. The focal length modulation is a key function of the confocal sensor. The mechanism of the focal length modulation determines the measurement speed and range. Here, we propose application of the micro-machined varifocal mirror for the modulation. The varifocal mirror can realize faster modulation, small size, and low energy consumption for the confocal displacement sensor. The electrostatically actuated varifocal mirror made by single crystalline silicon is used. The working distance of the sensor is designed to be 31 mm. The actuating range at 7 kHz is 310 μm. The linearity error in the actuating range is from -1.1% to 1.2%.
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http://dx.doi.org/10.1364/AO.56.006911 | DOI Listing |
Accurate and repeatable measurement of the radius of curvature (RoC) of spherical sample surfaces is of great importance in optics. This importance lies in the ubiquitous use of spherical optical elements such as curved mirrors and lenses. Due to a high measurement sensitivity, interferometric techniques are often deployed for accurate characterization of the sample surface RoC.
View Article and Find Full Text PDFMicrosyst Nanoeng
October 2023
Silicon Austria Labs, Villach, Austria.
Recent advances brought the performance of MEMS-based varifocal mirrors to levels comparable to conventional ultra-high-speed focusing devices. Varifocal mirrors are becoming capable of high axial resolution exceeding 300 resolvable planes, can achieve microsecond response times, continuous operation above several hundred kHz, and can be designed to combine focusing with lateral steering in a single-chip device. This survey summarizes the past 50 years of scientific progress in varifocal MEMS mirrors, providing the most comprehensive study in this field to date.
View Article and Find Full Text PDFNat Commun
July 2023
Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxon, OX11 0DE, UK.
Visible light optical elements such as lenses and mirrors have counterparts for X-rays. In the visible regime, a variable focusing power can be achieved by an Alvarez lens which consists of a pair of inline planar refractors with a cubic thickness profile. When the two refractors are laterally displaced in opposite directions, the parabolic component of the wavefront is changed resulting in a longitudinal displacement of the focus.
View Article and Find Full Text PDFBiomed Opt Express
November 2022
PhotoMedicine Labs, Department of Systems Design Engineering, University of Waterloo, 200 University Ave W, Waterloo, ON, N2L 3G1, Canada.
Optically shifting the focal plane to allow depth scanning of delicate biological structures and processes in their natural environment offers an appealing alternative to conventional mechanical scanning. Our technique uses a deformable mirror-based photoacoustic remote sensing microscopy (PARS) with a focus shifting of Δz ∼ 240 µm. We achieve this by integrating a deformable mirror that functions as a varifocal mirror for axial scanning.
View Article and Find Full Text PDFFront Bioeng Biotechnol
July 2022
Biomimetics Laboratory, Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand.
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