An optical tilt sensor based on a phase-sensitive diffraction grating with direct intensity-modulated scheme is proposed in this paper. The tilt sensor consists of a coherent light source, an integrated grating, a mechanical sensing part, and an optical signal processing circuit. The mechanical sensing part consists of a bulk proof mass and two cantilevers that can be fabricated with a two-mask process on a silicon-on-insulator substrate. A phase-sensitive diffraction grating, which was formed with the integrated grating and the upper surface of the proof mass, acts as the sensing element for the tilt measurement. Experimental results show this tilt sensor provides the optimal tilt sensitivity of 1.15 V/° and resolution of about 0.0046°, and a measurement range of ±20° in a rotational plane that is perpendicular to the direction of the earth's gravity.
In this paper, a MOEMS accelerometer with integrated-grating-based optical interference detection is presented. The
acceleration sensor consists of an integrated grating on a transparent substrate and a mechanical part of a bulk silicon
proof mass suspended by cantilevers attached to the silicon support substrate. The proof mass and cantilevers were
fabricated with a two-mask process on one silicon-on-insulator (SOI) wafer. A phase sensitive diffractive grating was
formed with the grating and the upper surface of the proof mass, which acts as a reflective mirror. Illuminating the
grating with coherent light generates a series of diffracted optical beams, whose angles remain fixed, but whose
intensities are modulated by the relative distance between the grating and the proof mass. Distance alteration caused by
vibratory accelerations, changed the intensities of the diffracted beams, which could be detected by a differential circuit
to get the variety of acceleration. Experimental results demonstrated that this MOEMS accelerometer has good
performance with sensitivity of 3.63x104V/g and a dynamic range of ±5g.
White-light interferometry is always an extremely useful and powerful tool for optical surface measurement. In this
paper, a novelty method based on rapid positioning and fast surface measurement is proposed. The adjustment of optical
path difference (OPD) is done automatically by a wavelength scanning method, and the processing of white-light
interference patterns is accelerated by GPGPU which stands for General-Purpose computation on Graphics Processing
Units, also known as GPU Computing. Graphics Processing Units are high-performance many-core processors in which
the data are processed in parallel. As a result, the time we need to obtain a surface shape is reduced to ten percents
compared with the conventional white-light interferometry. With these advantages, it is possible to measure a rough and
areal surface in a short time.
A new type of accelerometer is advanced which is based on optical fiber multi-mode interference (MMI). We use a
structure that a multi-mode fiber connected to two single mode fibers as the sensing part of the accelerometer. By
measuring the changes of the output spectrum can get the acceleration. This paper describes the principle of the
accelerometer based on multi-mode interference, and a theoretical simulation is performed. In the experiment a
Piezoelectric Ceramic is applied to simulate the Static Acceleration. The result manifests that this type of accelerometer
has a great dynamic range and a good resolution, also it's easy to fabricate and low cost.
An optical accelerometer with a bulk-micromachined silicon proof mass and a microfiber loop resonator (MLR) sensor was developed. The MLR was fixed on the surface of the cantilever beam. The proof mass and cantilever beam were fabricated with a two-mask process. An accelerometer with a range of ±20 g and output sensitivity 624.7 mV/g was fabricated. The design, simulation, fabrication, and preliminary results are presented.
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