A differentially amplified Hall effect displacement sensor for positioning control of a long-range flexure stage.

This paper presents a novel positioning feedback sensor using a pair of Hall effect elements on a long-range flexure stage. The proposed Hall effect positioning feedback sensor eliminates error and uncertainty by measuring the center of the flexure stage, where a machine tool or measurement probes would take place in the industrial application. A pair of Hall effect elements were amplified in a differential configuration as the cylindrical permanent magnet enclosed in the center of the shuttle in the flexure stage that moves back and forth, generating a uniform gradient magnetic flux intensity.

Robust, Ultrathin, and Highly Sensitive Reduced Graphene Oxide/Silk Fibroin Wearable Sensors Responded to Temperature and Humidity for Physiological Detection.

Skin temperature and skin humidity are used for monitoring physiological processes, such as respiration. Despite advances in wearable temperature and humidity sensors, the fabrication of a durable and sensitive sensor for practical uses continues to pose a challenge. Here, we developed a durable, sensitive, and wearable temperature and humidity sensor.

Geometric part error and material property profile separation technique of the additively manufactured and post-processed rods.

This paper presents novel surface profilometry for both geometric part error and metallurgical material property distribution measurements of the additively manufactured and post-processed rods. The measurement system, the so-called fiber optic-eddy current sensor, consists of a fiber optic displacement sensor and an eddy current sensor. The electromagnetic coil was wrapped around the probe of the fiber optic displacement sensor.

Smart Flexible 3D Sensor for Monitoring Orthodontics Forces: Prototype Design and Proof of Principle Experiment.

There is a critical need for an accurate device for orthodontists to know the magnitude of forces exerted on the tooth by the orthodontic brackets. Here, we propose a new orthodontic force measurement principle to detect the deformation of the elastic semi-sphere sensor. Specifically, we aimed to detail technical issues and the feasibility of the sensor performance attached to the inner surface of the orthodontic aligner or on the tooth surface.

Enhancement of knife-edge interferometry for edge topography characterization.

This paper introduces an optical measurement technique to enhance knife-edge interferometry (KEI) for edge topography characterization with a high resolution by shaping a beam of light incident on the sharp edge. The enhanced KEI forms spherical wavelets as a new light source by focusing a beam before the sharp edge by using an objective lens, and those wavelets interfere with the secondary wavelets diffracted at the sharp edge along the propagation direction. Unlike a conventional KEI that is limited to low spatial resolution due to a relatively large beam diameter, the enhanced KEI can increase the fringe spatial frequency and produce more data necessary for fringe analysis toward edge topography characterization.

A monolithic linear motion platform driven by a piezoelectric and fluidic pressure-fed dual mechanism.

This paper presents a novel dual-mode motion mechanism capable of achieving nanopositioning on a monolithic linear motion platform. Unlike conventional dual-mode stages that use piezoelectric (PZT)- and electromagnetic-combined or similar actuation mechanisms comprising two separate motion axes, the dual-mode actuation was developed by combining a PZT for a coarse motion and a fluidic pressure-fed mechanism (FPFM) for a fine motion and was implemented in a monolithic flexure stage fabricated by metal additive manufacturing. The FPFM actuates the flexure stage by pressuring the media in the fluidic channels created inside the flexure spring structures.

Knife-edge interferogram analysis for corrosive wear propagation at sharp edges.

This paper presents a novel noncontact measurement and inspection method based on knife-edge diffraction theory for corrosive wear propagation monitoring at a sharp edge. The degree of corrosion on the sharp edge was quantitatively traced in process by knife-edge interferometry (KEI). The measurement system consists of a laser diode, an avalanche photodiode, and a linear stage for scanning.

A novel sensor for two-degree-of-freedom motion measurement of linear nanopositioning stage using knife edge displacement sensing technique.

This paper presents a novel method for measuring two-degree-of-freedom (DOF) motion of flexure-based nanopositioning systems based on optical knife-edge sensing (OKES) technology, which utilizes the interference of two superimposed waves: a geometrical wave from the primary source of light and a boundary diffraction wave from the secondary source. This technique allows for two-DOF motion measurement of the linear and pitch motions of nanopositioning systems. Two capacitive sensors (CSs) are used for a baseline comparison with the proposed sensor by simultaneously measuring the motions of the nanopositioning system.

A curved edge diffraction-utilized displacement sensor for spindle metrology.

This paper presents a new dimensional metrological sensing principle for a curved surface based on curved edge diffraction. Spindle error measurement technology utilizes a cylindrical or spherical target artifact attached to the spindle with non-contact sensors, typically a capacitive sensor (CS) or an eddy current sensor, pointed at the artifact. However, these sensors are designed for flat surface measurement.

Compliance and control characteristics of an additive manufactured-flexure stage.

This paper presents a compliance and positioning control characteristics of additive manufactured-nanopositioning system consisted of the flexure mechanism and voice coil motor (VCM). The double compound notch type flexure stage was designed to utilize the elastic deformation of two symmetrical four-bar mechanisms to provide a millimeter-level working range. Additive manufacturing (AM) process, stereolithography, was used to fabricate the flexure stage.

Novel design and sensitivity analysis of displacement measurement system utilizing knife edge diffraction for nanopositioning stages.

This paper presents a novel design and sensitivity analysis of a knife edge-based optical displacement sensor that can be embedded with nanopositioning stages. The measurement system consists of a laser, two knife edge locations, two photodetectors, and axillary optics components in a simple configuration. The knife edge is installed on the stage parallel to its moving direction and two separated laser beams are incident on knife edges.

Phase-locked loop based on machine surface topography measurement using lensed fibers.

We present the phase-locked loop (PLL)-based metrology concept using lensed fibers for on-machine surface topography measurement. The shape of a single-mode fiber at the endface was designed using an ABCD matrix method, and two designed lensed fibers-the ball type and the tapered type-were fabricated, and the performance was evaluated, respectively. As a result, the interferometric fringe was not found in the case of the ball lensed fiber, but the machined surface could be measured by utilization of autofocusing and intensity methods.

Design of retrodiffraction gratings for polarization-insensitive and polarization-sensitive characteristics by using the Taguchi method.

We present the design of retrodiffraction gratings that utilize total internal reflection (TIR) in a lamellar configuration to achieve high performance for both TE and TM polarized light and polarization-sensitive performance for gratings behaving as polarizer filters; the design was based on rigorous coupled wave analysis (RCWA) and the Taguchi method. The components can thus be fabricated from a single dielectric material and do not have to be coated with a metallic or dielectric film layer to enhance the reflectance. The effects of the structural and optical parameters of lamellar gratings were investigated, and the TIR gratings in a lamellar configuration were structurally and optically optimized in terms of the signal-to-noise ratio (S/N) and a statistical analysis of variance (ANOVA) of the refractive index, grating period, filling factor, and grating depth as control factors and the estimated efficiency by RCWA as a noise factor.