Performance characterisation of a new photo-microsensor based sensing head for displacement measurement

This paper presents a robust displacement sensor with nanometre-scale resolution over a micrometre range. It is composed of low cost commercially available slotted photo-microsensors (SPMs). The displacement sensor is designed with a particular arrangement of a compact array of SPMs with specially designed shutter assembly and signal processing to significantly reduce sensitivity to ambient light, input voltage variation, circuit electronics drift, etc. The sensor principle and the characterisation results are described in this paper. The proposed prototype sensor has a linear measurement range of 20 μm and resolution of 21 nm. This kind of sensor has several potential applications, including mechanical structural deformation monitoring system

Review of Fiber Optic Displacement Sensors

Displacement Measurements Are of Significant Importance in a Variety of Critical Scientific and Engineering Fields, Such as Gravitational Wave Detection, Geophysical Research, and Manufacturing Industries. Due to the Inherent Advantages Such as Compactness, High Sensitivity, and Immunity to Electromagnetic Interference, in Recent Years, Fiber Optic Sensors Have Been Widely Used in an Expansive Range of Sensing Applications, Ranging from Infrastructural Health Monitoring to Chemical and Biological Sensing. of Particular Interest Here, Fiber Optic Displacement Sensors Have Gained Wide Interest and Have Evolved from Basic Intensity Modulation-Based Configurations to More Advanced Structures, Such as Fiber Bragg Grating (FBG)-Based and Interferometric Configurations. This Article Reviews Specifically the Advanced Fiber Optic Displacement Sensing Techniques that Have Been Developed in the Past Two Decades. Details Regarding the Working Principle, Sensor Design, and Performance Measures of FBG-Based, Interferometers-Based (Including the Fabry-Perot Interferometer, the Michelson Interferometer, and the Multimode Interferometer), Microwave Photonics-Based, and Surface Plasmon Resonance-Based Fiber Optic Displacement Sensors Are Given. Challenges and Perspectives on Future Research in the Development of Practical and High-Temperature Tolerant Displacement Sensors Are Also Discussed

Development of a Traceable Atomic Force Microscope with Interferometer and Compensation Flexure Stage

Entwicklung eines ruckfuhrbaren Rasterkraftmikroskops auf der Basis von Interferometern und einer geregelten Einkorperfuhrung Abstrakt Rastersondenmikroskope, zu denen unter anderem Rastertunnelmikroskope (STM) und Rasterkraftmikroskope (AFM) gezahlt werden, werden an vielen Stellen in der Material- und Oberflachenforschung, der Halbleitertechnologie sowie der Biotechnologie angewendet. Sie sind zudem denkbare Werkzeuge der Nanotechnologien, so beispielsweise der Nanolithographie. Zudem konnen sie der Manipulation von Atomen und zur Nanometrologie dienen. Kommerzielle AFM bestehen unter anderem aus einem Laser, Photoempfanger, Regler, Piezoantriebssystem sowie einem Tastsystem. Dabei kommt den Piezoelementen des Antriebssystems besondere Bedeutung zu. Die von Piezoelementen bekannten Nachteile, wie Nichtlinearitat, Hysterese, Alterung, thermische Drift, Kriechen und Ubersprechen, konnen durchaus 20% der Messabweichungen bei Vorwartssteuerung verursachen. Daher sollten AFM, Metrologiestandards entsprechend, zur Reduzierung der Mesunsicherheit regelmasig ruckfuhrbar kalibriert werden. Das Ziel der vorliegenden Arbeit bestand in der Entwicklung eines ruckfuhrbaren Rasterkraftmikroskops (Traceable Atomic Force Microscope, TAFM) zum Einsatz als staatliches Normal zur ruckfuhrbaren Vermessung von Normalen im Nanometer- Bereich fur die taiwanesische Industrie. Das TAFM wurde als Kombination eines kommerziellen AFM, zwei Laserinterferometern, einer aktiv geregelten dreiachsigen Prazisionsfuhrung, einem Metrologierahmen aus Super-Invar, einer Schwingungsdampfung sowie einer temperaturgeregelten Umhausung konzipiert und aufgebaut. Zur Reduzierung des Abbe-Offsets wurden die Interferometer derart angeordnet, dass sich ihre virtuell verlangerten Messstrahlen im Antastpunkt des Cantilevers und damit direkt auf der Probenoberflache im Messpunkt schneiden. Eine einwandfreie Referenzbewegung des Systems wurde durch die eingesetzten Prazisionsfuhrungen sichergestellt, wahrend die direkte Ruckfuhrbarkeit auf die Definition der Langeneinheit ?Meter" durch den Einsatz von zwei Laser- Interferometern erreicht wurde. Die ermittelte erweiterte Messunsicherheit des TAFM fur die laterale Messung einer Lange von 292 nm betrugt bei einer statistischen Sicherheit von 95% unter Berucksichtigung von 29 Freiheitsgraden 2,5 nm. Da die ermittelte erweiterte Messunsicherheit fur laterale Langenmessungen noch nicht zufriedenstellend und die Ruckfuhrbarkeit in Richtung der Z-Achse nicht gewahrleistet ist, soll das TAFM verbessert werden, um perspektivisch eine Messunsicherheit von 0,5 nm in allen drei Messachsen zu erreichen. Dieses Ziel kann zunachst durch den Einbau eines weiteren Laserinterferometers zur Kalibrierung des Messystems der Z-Achse erreicht werden. Zusatzlich sollte die Umhausung statt auf einem Tisch auf dem schwingungsarmeren Boden platziert werden, was das Rauschen der Interferometer auf weniger als 5 nm reduzieren sollte. Ein verstarkter Metrologierahmen, die Verlagerung der Referenzspiegel vom AFM auf die Prazisionsfuhrung und verkurzte Messkreise, die Konstruktion aller Teile aus dem gleichen Material, ein symmetrischer mechanischer Aufbau und der Einsatz einer aktiven Temperaturregelung mit einer Temperaturstabilitat von 20¡Ó0.1 ¢XC sind weitere wichtige Schritte.Scanning Probe Microscopes (SPMs), generally including such instruments as Scanning Tunneling Microscopes (STMs) and Atomic Force Microscopes (AFMs), have been widely applied to measure engineering surfaces in a variety of fields, such as material sciences, semiconductor industry, and biotechnology. SPMs will also be a potential tool in nanotechnology, for example nanolithography, atom manipulation, and nanometrology. Normally, a commercial AFM consists of a laser, a photo-detector, a controller, a piezo-scanner, and a cantilever tip. The piezo-scanner is critical to the performance of AFMs. The intrinsic properties of piezo-scanners, for instance non-linearity, hysteresis, aging, thermal drift, creep, and coupling effect will result in measurement errors that may reach up to 20 % of the reading. To reduce major measurement errors mentioned above, an AFM should be periodically calibrated with a traceable standard. The goal of my research study was to design a state-of-the-art Traceable Atomic Force Microscope (TAFM) to be used as a primary realization of nanometer scale standards for Taiwan industry. The TAFM was composed of a commercial AFM, two laser interferometers, a 3-axis active compensation flexure stage, a super-Invar metrology frame, a vibration isolator, and a temperature-controlled enclosed box with circulating water. To eliminate the Abbe-offset, the surface-plane of specimens was arranged on the same plane-level to the laser beams emitted by interferometers. The compensation flexure stage was aimed to provide a perfect reference motion mechanism. To achieve the direct traceability to the definition of meter, two interferometers were added to the flexure stage. The TAFM was evaluated to have an expanded uncertainty of 2.5 nm at a confidence level of 95 % and 29 degrees of freedom for a nominal pitch value of 292 nm. Since the expanded uncertainty of pitch measurement is not satisfactory and there is no traceability in the Z direction. The TAFM needs to be improved to meet the requirement of an expanded uncertainty of no more than 0.5 nm at 95 % confidence level at all three axes. The requirement can be achieved by the following improvements: A laser interferometer is added to the flexure stage for Z-height calibration. To reduce the noise of laser interferometer to about 5 nm, the support of the enclosed box is moved from tabletop to the floor. The metrology frame is improved by changing the reference mirrors from AFM to flexure stage, thickening the super-Invar frame, shortening the structure loop and metrology loop, using one material, and realizing a symmetrical mechanism design. The passive temperature control is changed to active temperature control, which will approach an anticipative temperature stability of (20¡Ó0.1) ¢XC in the measuring volume

Collaborative development of diffraction-limited beamline optical systems at US DOE light sources

An ongoing collaboration among four US Department of Energy (DOE) National Laboratories has demonstrated key technology prototypes and software modeling tools required for new high-coherent flux beamline optical systems. New free electron laser (FEL) and diffraction-limited storage ring (DLSR) light sources demand wavefront preservation from source to sample to achieve and maintain optimal performance. Fine wavefront control was achieved using a novel, roomtemperature cooled mirror system called REAL (resistive element adjustable length) that combines cooling with applied, spatially variable auxiliary heating. Single-grating shearing interferometry (also called Talbot interferometry) and Hartmann wavefront sensors were developed and used for optical characterization and alignment on several beamlines, across a range of photon energies. Demonstrations of non-invasive hard x-ray wavefront sensing were performed using a thin diamond single-crystal as a beamsplitter

同心円回析格子と位相変調干渉計を用いた軸受のラジアル アキシャル アンギュラモーションの同時測定法

国立大学法人長岡技術科学大

Heterodyne common-path grating interferometer with Littrow configuration

[[abstract]]This paper presents a heterodyne common-path grating interferometer with Littrow configuration (HCGIL). The HCGIL can effectively overcome environmental disturbance effect and the DC offset and the amplitude variation of the measurement signals. Experimental results match well with the HP5529A results for long-range measurements. Results also show that the estimated measurement resolution is 0.15 ± 0.027 nm. The stability of the HCGIL is −0.41 ± 0.23 nm. Therefore, the HCGIL has potential for subnanometer resolution and long-range applications.[[notice]]補正完畢[[incitationindex]]SCI[[booktype]]電子

Calibration of piezoelectric positioning actuators using a reference voltage-to-displacement transducer based on quartz tuning forks

We use a piezoelectric quartz tuning fork to calibrate the displacement of ceramic piezoelectric scanners which are widely employed in scanning probe microscopy. We measure the static piezoelectric response of a quartz tuning fork and find it to be highly linear, non-hysteretic and with negligible creep. These performance characteristics, close to those of an ideal transducer, make quartz transducers superior to ceramic piezoelectric actuators. Furthermore, quartz actuators in the form of a tuning fork have the advantage of yielding static displacements comparable to those of local probe microscope scanners. We use the static displacement of a quartz tuning fork as a reference to calibrate the three axis displacement of a ceramic piezoelectric scanner. Although this calibration technique is a non-traceable method, it can be more versatile than using calibration grids because it enables to characterize the linear and non-linear response of a piezoelectric scanner in a broad range of displacements, spanning from a fraction of a nanometer to hundreds of nanometers. In addition, the creep and the speed dependent piezoelectric response of ceramic scanners can be studied in detail.Comment: 9 pages, 3 figure

DEVELOPMENT OF A VERSATILE HIGH SPEED NANOMETER LEVEL SCANNING MULTI-PROBE MICROSCOPE

The motivation for development of a multi-probe scanning microscope, presented in this dissertation, is to provide a versatile measurement tool mainly targeted for biological studies, especially on the mechanical and structural properties of an intracellular system. This instrument provides a real-time, three-dimensional (3D) scanning capability. It is capable of operating on feedback from multiple probes, and has an interface for confocal photo-detection of fluorescence-based and single molecule imaging sensitivity. The instrument platform is called a Scanning Multi-Probe Microscope (SMPM) and enables 45 microm by 45 microm by 10 microm navigation of specimen with simultaneous optical and mechanical probing with each probe location being adjustable for collocation or for probing with known probe separations. The 3D positioning stage where the specimen locates was designed to have nanometer resolution and repeatability at 10 Hz scan speed with either open loop or closed loop operating modes. The fine motion of the stage is comprises three orthogonal flexures driven by piezoelectric actuators via a lever linkage. The flexures design is able to scan in larger range especially in z axis and serial connection of the stages helps to minimize the coupling between x, y and z axes. Closed-loop control was realized by the capacitance gauges attached to a rectangular block mounted to the underside of the fine stage upon which the specimen is mounted. The stage's performance was studied theoretically and verified by experimental test. In a step response test and using a simple proportional and integral (PI) controller, standard deviations of 1.9 nm 1.8 nm and 0.41 nm in the x, y and z axes were observed after settling times of 5 ms and 20 ms for the x and y axes. Scanning and imaging of biological specimen and artifact grating are presented to demonstrate the system operation. For faster, short range scanning, novel ultra-fast fiber scanning system was integrated into the xyz fine stage to achieve a super precision dual scanning system. The initial design enables nanometer positioning resolution and runs at 100 Hz scan speed. Both scanning systems are capable of characterization using dimensional metrology tools. Additionally, because the high-bandwidth, ultra-fast scanning system operates through a novel optical attenuating lever, it is physically separate from the longer range scanner and thereby does not introduce additional positioning noise. The dual scanner provides a fine scanning mechanism at relatively low speed and large imaging area using the xyz stage, and focus on a smaller area of interested in a high speed by the ultra-fast scanner easily. Such functionality is beneficial for researchers to study intracellular dynamic motion which requires high speed imaging. Finally, two high end displacement sensor systems, a knife edge sensor and fiber interferometer, were demonstrated as sensing solutions for potential feedback tools to boost the precision and resolution performance of the SMPM