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22 pages, 12055 KiB

Open AccessArticle

An Optical Measuring Transducer for a Micro-Opto-Electro-Mechanical Micro-g Accelerometer Based on the Optical Tunneling Effect

by Evgenii Barbin, Tamara Nesterenko, Aleksei Koleda, Evgeniy Shesterikov, Ivan Kulinich and Andrey Kokolov

Micromachines 2023, 14(4), 802; https://doi.org/10.3390/mi14040802 - 31 Mar 2023

Cited by 3 | Viewed by 1080

Abstract

Micro-opto-electro-mechanical (MOEM) accelerometers that can measure small accelerations are attracting growing attention thanks to their considerable advantages—such as high sensitivity and immunity to electromagnetic noise—over their rivals. In this treatise, we analyze 12 schemes of MOEM-accelerometers, which include a spring mass and a [...] Read more.

Micro-opto-electro-mechanical (MOEM) accelerometers that can measure small accelerations are attracting growing attention thanks to their considerable advantages—such as high sensitivity and immunity to electromagnetic noise—over their rivals. In this treatise, we analyze 12 schemes of MOEM-accelerometers, which include a spring mass and a tunneling-effect-based optical sensing system containing an optical directional coupler consisting of a fixed and a movable waveguide separated by an air gap. The movable waveguide can perform linear and angular movement. In addition, the waveguides can lie in single or different planes. Under acceleration, the schemes feature the following changes to the optical system: gap, coupling length, overlapping area between the movable and fixed waveguides. The schemes with altering coupling lengths feature the lowest sensitivity, yet possess a virtually unlimited dynamic range, which makes them comparable to capacitive transducers. The sensitivity of the scheme depends on the coupling length and amounts to 11.25 × 10³ m⁻¹ for a coupling length of 44 μm and 30 × 10³ m⁻¹ for a coupling length of 15 μm. The schemes with changing overlapping areas possess moderate sensitivity (1.25 × 10⁶ m⁻¹). The highest sensitivity (above 6.25 × 10⁶ m⁻¹) belongs to the schemes with an altering gap between the waveguides. Full article

(This article belongs to the Special Issue Optical MEMS, Volume III)

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16 pages, 5677 KiB

Open AccessArticle

Development of an Optoelectronic Integrated Sensor for a MEMS Mirror-Based Active Structured Light System

by Xiang Cheng, Shun Xu, Yan Liu, Yingchao Cao, Huikai Xie and Jinhui Ye

Micromachines 2023, 14(3), 561; https://doi.org/10.3390/mi14030561 - 27 Feb 2023

Cited by 1 | Viewed by 1541

Abstract

Micro-electro-mechanical system (MEMS) scanning micromirrors are playing an increasingly important role in active structured light systems. However, the initial phase error of the structured light generated by a scanning micromirror seriously affects the accuracy of the corresponding system. This paper reports an optoelectronic [...] Read more.

Micro-electro-mechanical system (MEMS) scanning micromirrors are playing an increasingly important role in active structured light systems. However, the initial phase error of the structured light generated by a scanning micromirror seriously affects the accuracy of the corresponding system. This paper reports an optoelectronic integrated sensor with high irradiance responsivity and high linearity that can be used to correct the phase error of the micromirror. The optoelectronic integrated sensor consists of a large-area photodetector (PD) and a receiving circuit, including a post amplifier, an operational amplifier, a bandgap reference, and a reference current circuit. The optoelectronic sensor chip is fabricated in a 180 nm CMOS process. Experimental results show that with a 5 V power supply, the optoelectronic sensor has an irradiance responsivity of 100 mV/(μW/cm²) and a −3 dB bandwidth of 2 kHz. The minimal detectable light power is about 19.4 nW, which satisfies the requirements of many active structured light systems. Through testing, the application of the chip effectively reduces the phase error of the micromirror to 2.5%. Full article

(This article belongs to the Special Issue Optical MEMS, Volume III)

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15 pages, 6671 KiB

Open AccessArticle

AlScN Piezoelectric MEMS Mirrors with Large Field of View for LiDAR Application

by Yichen Liu, Lihao Wang, Yongquan Su, Yuyao Zhang, Yang Wang and Zhenyu Wu

Micromachines 2022, 13(9), 1550; https://doi.org/10.3390/mi13091550 - 18 Sep 2022

Cited by 14 | Viewed by 3925

Abstract

This paper presents AlScN piezoelectric two-axis MEMS mirrors with gimbal-less and gimbaled designs fabricated in a CMOS-compatible manner. Integrated piezoelectric sensors provided feedback signals of the actual mirror positions. The mirror with a diameter of 1.5 mm possessed adjustable optical tilt angles of [...] Read more.

This paper presents AlScN piezoelectric two-axis MEMS mirrors with gimbal-less and gimbaled designs fabricated in a CMOS-compatible manner. Integrated piezoelectric sensors provided feedback signals of the actual mirror positions. The mirror with a diameter of 1.5 mm possessed adjustable optical tilt angles of up to 22.6° @ 30 V, with a high resonance frequency of about 8.2 kHz, while the 3 mm mirror reached 48.5° @ 41 V. The mirror with the gimbaled structure exhibited an excellent field of view and good mechanical decoupling. Additionally, a significant improvement in mirror scanning performance was observed in a vacuum (4 Pa), proving that the optical field of view was magnified by more than a factor of 10. Full article

(This article belongs to the Special Issue Optical MEMS, Volume III)

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12 pages, 1822 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Integrated Amplitude and Phase Monitor for Micro-Actuators

by Sandra Nicole Manosalvas-Kjono, Ronald Quan and Olav Solgaard

Micromachines 2022, 13(8), 1360; https://doi.org/10.3390/mi13081360 - 20 Aug 2022

Cited by 2 | Viewed by 1758

Abstract

Micro-actuators driven on resonance maximize reach and speed; however, due to their sensitivity to environmental factors (e.g., temperature and air pressure), the amplitude and phase response must be monitored to achieve an accurate actuator position. We introduce an MEMS (microelectromechanical system) amplitude and [...] Read more.

Micro-actuators driven on resonance maximize reach and speed; however, due to their sensitivity to environmental factors (e.g., temperature and air pressure), the amplitude and phase response must be monitored to achieve an accurate actuator position. We introduce an MEMS (microelectromechanical system) amplitude and phase monitor (MAPM) with a signal-to-noise ratio of 51 dB and 11.0 kHz bandwidth, capable of simultaneously driving and sensing the movement of 1D and 2D electrostatically driven micro-actuators without modifying the chip or its packaging. The operational principle is to electromechanically modulate the amplitude of a high-frequency signal with the changing capacitance of the micro-actuator. MAPM operation is characterized and verified by simultaneously measuring the amplitude and phase frequency response of commercial micromirrors. We demonstrate that the MAPM circuitry is insensitive to complex relationships between capacitance and position of the MEMS actuators, and it is capable of giving real-time read-out of the micromirror motion. Our measurements also reveal and quantify observations of phase drift and crosstalk in 2D resonant operation. Measurements of phase changes over time under normal operation also verify the need for phase monitoring. The open-loop, high-sensitivity position sensor enables detailed characterization of dynamic micro-actuator behavior, leading to new insights and new types of operation, including improved control of nonlinear motion. Full article

(This article belongs to the Special Issue Optical MEMS, Volume III)

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11 pages, 1807 KiB

Open AccessArticle

Reconfigurable Angular Resolution Design Method in a Separate-Axis Lissajous Scanning MEMS LiDAR System

by Fahu Xu, Dayong Qiao, Changfeng Xia, Xiumin Song, Wenhui Zheng, Yaojun He and Qiaodan Fan

Micromachines 2022, 13(3), 353; https://doi.org/10.3390/mi13030353 - 23 Feb 2022

Cited by 3 | Viewed by 1883

Abstract

MEMS-based LiDAR with a low cost and small volume is a promising solution for 3D measurement. In this paper, a reconfigurable angular resolution design method is proposed in a separate-axis Lissajous scanning MEMS LiDAR system. This design method reveals the influence factors on [...] Read more.

MEMS-based LiDAR with a low cost and small volume is a promising solution for 3D measurement. In this paper, a reconfigurable angular resolution design method is proposed in a separate-axis Lissajous scanning MEMS LiDAR system. This design method reveals the influence factors on the angular resolution, including the characteristics of the MEMS mirrors, the laser duty cycle and pulse width, the processing time of the echo signal, the control precision of the MEMS mirror, and the laser divergence angle. A simulation was carried out to show which conditions are required to obtain different angular resolutions. The experimental results of the 0.2° × 0.62° and 0.2° × 0.15° (horizontal × vertical) angular resolutions demonstrate the feasibility of the design method to realize a reconfigurable angular resolution in a separate-axis Lissajous scanning MEMS LiDAR system by employing MEMS mirrors with different characteristics. This study provides a reasonable potential to obtain a high and flexible angular resolution for MEMS LiDAR. Full article

(This article belongs to the Special Issue Optical MEMS, Volume III)

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11 pages, 3259 KiB

Open AccessArticle

Fast Synchronization Method of Comb-Actuated MEMS Mirror Pair for LiDAR Application

by Fahu Xu, Dayong Qiao, Changfeng Xia, Xiumin Song and Yaojun He

Micromachines 2021, 12(11), 1292; https://doi.org/10.3390/mi12111292 - 21 Oct 2021

Cited by 3 | Viewed by 2173

Abstract

MEMS-based LiDAR (micro-electro–mechanical system based light detection and ranging), with a low cost and small volume, becomes a promising solution for the two-dimensional (2D) and three-dimensional (3D) optical imaging. A semi-coaxial MEMS LiDAR design, based on a synchronous MEMS mirror pair, was proposed [...] Read more.

MEMS-based LiDAR (micro-electro–mechanical system based light detection and ranging), with a low cost and small volume, becomes a promising solution for the two-dimensional (2D) and three-dimensional (3D) optical imaging. A semi-coaxial MEMS LiDAR design, based on a synchronous MEMS mirror pair, was proposed in our early study. In this paper, we specifically reveal the synchronization method of the comb-actuated MEMS mirror pair, including the frequency, amplitude, and phase synchronization. The frequency sweeping and phase adjustment are simultaneously implemented to accelerate the MEMS mirror synchronization process. The experiment is set up and the entire synchronization process is completed within 5 s. Eventually, a one-beam MEMS LiDAR system with the synchronous MEMS mirror pair is set up and a LiDAR with a field of view (FOV) of 60°, angular resolution of 0.2°, and frame rate of 360 Hz is obtained. The experimental results verify the feasibility of the MEMS mirror synchronization method and show a promising potential application prospect for the MEMS LiDAR system. Full article

(This article belongs to the Special Issue Optical MEMS, Volume III)

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Review

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24 pages, 10568 KiB

Open AccessReview

MEMS Enabled Miniature Two-Photon Microscopy for Biomedical Imaging

by Xiaomin Yu, Liang Zhou, Tingxiang Qi, Hui Zhao and Huikai Xie

Micromachines 2023, 14(2), 470; https://doi.org/10.3390/mi14020470 - 17 Feb 2023

Cited by 6 | Viewed by 2925

Abstract

Over the last decade, two-photon microscopy (TPM) has been the technique of choice for in vivo noninvasive optical brain imaging for neuroscientific study or intra-vital microendoscopic imaging for clinical diagnosis or surgical guidance because of its intrinsic capability of optical sectioning for imaging [...] Read more.

Over the last decade, two-photon microscopy (TPM) has been the technique of choice for in vivo noninvasive optical brain imaging for neuroscientific study or intra-vital microendoscopic imaging for clinical diagnosis or surgical guidance because of its intrinsic capability of optical sectioning for imaging deeply below the tissue surface with sub-cellular resolution. However, most of these research activities and clinical applications are constrained by the bulky size of traditional TMP systems. An attractive solution is to develop miniaturized TPMs, but this is challenged by the difficulty of the integration of dynamically scanning optical and mechanical components into a small space. Fortunately, microelectromechanical systems (MEMS) technology, together with other emerging micro-optics techniques, has offered promising opportunities in enabling miniaturized TPMs. In this paper, the latest advancements in both lateral scan and axial scan techniques and the progress of miniaturized TPM imaging will be reviewed in detail. Miniature TPM probes with lateral 2D scanning mechanisms, including electrostatic, electromagnetic, and electrothermal actuation, are reviewed. Miniature TPM probes with axial scanning mechanisms, such as MEMS microlenses, remote-focus, liquid lenses, and deformable MEMS mirrors, are also reviewed. Full article

(This article belongs to the Special Issue Optical MEMS, Volume III)

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27 pages, 16459 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Review of Electrothermal Micromirrors

by Yue Tang, Jianhua Li, Lixin Xu, Jeong-Bong Lee and Huikai Xie

Micromachines 2022, 13(3), 429; https://doi.org/10.3390/mi13030429 - 10 Mar 2022

Cited by 8 | Viewed by 3368

Abstract

Electrothermal micromirrors have become an important type of micromirrors due to their large angular scanning range and large linear motion. Typically, electrothermal micromirrors do not have a torsional bar, so they can easily generate linear motion. In this paper, electrothermal micromirrors based on [...] Read more.

Electrothermal micromirrors have become an important type of micromirrors due to their large angular scanning range and large linear motion. Typically, electrothermal micromirrors do not have a torsional bar, so they can easily generate linear motion. In this paper, electrothermal micromirrors based on different thermal actuators are reviewed, and also the mechanisms of those actuators are analyzed, including U-shape, chevron, thermo-pneumatic, thermo-capillary and thermal bimorph-based actuation. Special attention is given to bimorph based-electrothermal micromirrors due to their versatility in tip-tilt-piston motion. The exemplified applications of each type of electrothermal micromirrors are also presented. Moreover, electrothermal micromirrors integrated with electromagnetic or electrostatic actuators are introduced. Full article

(This article belongs to the Special Issue Optical MEMS, Volume III)

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