scholarly journals Axial Error of Spindle Measurements Using a High-Frequency-Modulated Interferometer

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 801
Author(s):  
Thanh-Trung Nguyen ◽  
Thanh-Tung Vu ◽  
Thanh-Dong Nguyen ◽  
Toan-Thang Vu
Keyword(s):  
High Precision ◽  
Modulation Frequency ◽  
Zeeman Effect ◽  
Machining Process ◽  
Measuring System ◽  
Laser Source ◽  
Small Displacement ◽  
Interference Signal ◽  
High Modulation ◽  
The Difference

In this paper, a novel, compact, and high-precision axial error measurement using a frequency-modulated interferometer is developed. Normally, heterodyne interferometers are a powerful system for small displacement measurements due to their property of being less sensitive to temperature and pressure variations. However, the maximum measurement speed of the heterodyne interferometer is around 5 m/s because it is usually limited by the difference in frequency between the two components of the laser beam, which is no larger than 3 MHz or 20 MHz corresponding laser source based on the Zeeman effect and acousto-optic modulator, respectively. The proposed measuring system is realized by modulating the frequency of the laser diode source at a high modulation frequency and using lock-in amplifiers to extract the harmonics of the interference signal. The measurement speed is proportional to the modulation frequency. Thus, the higher the modulation frequency, the higher the measuring speed attains. The frequency-modulated interferometer is then applied to measure the axial error of an ultra-precision spindle. The proposed system can be a capable solution for noncontact and high-precision spindle error measurements in the machining process.

scholarly journals A Displacement Measuring Interferometer Based on a Frequency-Locked Laser Diode with High Modulation Frequency

2020 ◽  
Vol 10 (8) ◽  
pp. 2693
Author(s):  
Thanh Tung Vu ◽  
Hong Hai Hoang ◽  
Toan Thang Vu ◽  
Ngoc Tam Bui
Keyword(s):  
Frequency Modulation ◽  
High Speed ◽  
Modulation Frequency ◽  
Laser Source ◽  
Interference Signal ◽  
Modulation Amplitude ◽  
Hyperfine Component ◽  
Synchronous Detection ◽  
High Modulation ◽  
Uncertainty Of Measurements

Laser interferometers can achieve a nanometer-order uncertainty of measurements when their frequencies are locked to the reference frequencies of the atom or molecule transitions. There are three types of displacement-measuring interferometers: homodyne, heterodyne, and frequency modulation (FM) interferometers. Among these types of interferometer, the FM interferometer has many advantageous features. The interference signal is a series of time-dependent harmonics of modulation frequency, so the phase shift can be detected accurately using the synchronous detection method. Moreover, the FM interferometer is the most suitable for combination with a frequency-locked laser because both require frequency modulation. In previous research, low modulation frequencies at some tens of kHz have been used to lock the frequency of laser diodes (LDs). The low modulation frequency for the laser source means that the maximum measurement speed of the FM interferometers is limited. This paper proposes a novel contribution regarding the application of a high-frequency modulation for an LD to improve both the frequency stability of the laser source and the measurement speed of the FM interferometer. The frequency of the LD was locked to an I2 hyperfine component at 1 MHz modulation frequency. A high bandwidth lock-in amplifier was utilized to detect the saturated absorption signals of the I2 hyperfine structure and induce the signal to lock the frequency of the LD. The locked LD was then used for an FM displacement measuring interferometer. Moreover, a suitable modulation amplitude that affected the signal-to-noise ratio of both the I2 absorption signal and the harmonic intensity of the interference signal was determined. In order to verify the measurement resolution of the proposed interferometer, the displacement induced by a piezo electric actuator was concurrently measured by the interferometer and a capacitive sensor. The difference of the displacement results was less than 20 nm. To evaluate the measurement speed, the interferometer was used to measure the axial error of a high-speed spindle at 500 rpm. The main conclusion of this study is that a stable displacement interferometer with high accuracy and a high measurement speed can be achieved using an LD frequency locked to an I2 hyperfine transition at a high modulation frequency.

scholarly journals Self-Referenced Multifrequency Phase-Resolved Luminescence Spectroscopy

Sensors ◽  
2020 ◽  
Vol 20 (19) ◽  
pp. 5482
Author(s):  
Angel de la Torre ◽  
Santiago Medina-Rodríguez ◽  
Jose C. Segura ◽  
Jorge F. Fernández-Sánchez
Keyword(s):  
Chemical Sensors ◽  
Modulation Frequency ◽  
Measuring System ◽  
Luminescence Lifetime ◽  
Luminescence Spectroscopy ◽  
Theoretical Formulation ◽  
Analog To Digital ◽  
Excitation Signal ◽  
Emission Signal ◽  
The Difference

Phase-resolved luminescence chemical sensors provide the analyte determination based on the estimation of the luminescence lifetime. The lifetime is estimated from an analysis of the amplitudes and/or phases of the excitation and emission signals at one or several modulation frequencies. This requires recording both the excitation signal (used to modulate the light source) and the emission signal (obtained from an optical transducer illuminated by the luminescent sensing phase). The excitation signal is conventionally used as reference, in order to obtain the modulation factor (the ratio between the emission and the excitation amplitudes) and/or the phase shift (the difference between the emission and the excitation phases) at each modulation frequency, which are used to estimate the luminescence lifetime. In this manuscript, we propose a new method providing the luminescence lifetimes (based either on amplitudes or phases) using only the emission signal (i.e., omitting the excitation signal in the procedure). We demonstrate that the luminescence lifetime can be derived from the emission signal when it contains at least two harmonics, because in this case the amplitude and phase of one of the harmonics can be used as reference. We present the theoretical formulation as well as an example of application to an oxygen measuring system. The proposed self-referenced lifetime estimation provides two practical advantages for luminescence chemical sensors. On one hand, it simplifies the instrument architecture, since only one analog-to-digital converter (for the emission signal) is necessary. On the other hand, the self-referenced estimation of the lifetime improves the robustness against degradation of the sensing phase or variations in the optical coupling, which reduces the recalibration requirements when the lifetimes are based on amplitudes.

Generalized Heterodyne Configurations for Photo-induced Force Microscopy

2019 ◽  
Author(s):  
Le Wang ◽  
Devon Jakob ◽  
Haomin Wang ◽  
Alexis Apostolos ◽  
Marcos M. Pires ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Repetition Rate ◽  
Modulation Frequency ◽  
High Harmonic ◽  
Chemical Imaging ◽  
Heterodyne Detection ◽  
Force Microscopy ◽  
Wide Range ◽  
The Difference ◽  
Afm Cantilever

<div>Infrared chemical microscopy through mechanical probing of light-matter interactions by atomic force microscopy (AFM) bypasses the diffraction limit. One increasingly popular technique is photo-induced force microscopy (PiFM), which utilizes the mechanical heterodyne signal detection between cantilever mechanical resonant oscillations and the photo induced force from light-matter interaction. So far, photo induced force microscopy has been operated in only one heterodyne configuration. In this article, we generalize heterodyne configurations of photoinduced force microscopy by introducing two new schemes: harmonic heterodyne detection and sequential heterodyne detection. In harmonic heterodyne detection, the laser repetition rate matches integer fractions of the difference between the two mechanical resonant modes of the AFM cantilever. The high harmonic of the beating from the photothermal expansion mixes with the AFM cantilever oscillation to provide PiFM signal. In sequential heterodyne detection, the combination of the repetition rate of laser pulses and polarization modulation frequency matches the difference between two AFM mechanical modes, leading to detectable PiFM signals. These two generalized heterodyne configurations for photo induced force microscopy deliver new avenues for chemical imaging and broadband spectroscopy at ~10 nm spatial resolution. They are suitable for a wide range of heterogeneous materials across various disciplines: from structured polymer film, polaritonic boron nitride materials, to isolated bacterial peptidoglycan cell walls. The generalized heterodyne configurations introduce flexibility for the implementation of PiFM and related tapping mode AFM-IR, and provide possibilities for additional modulation channel in PiFM for targeted signal extraction with nanoscale spatial resolution.</div>

Sources of the Scalp-Recorded Amplitude-Modulation Following Response

2002 ◽  
Vol 13 (04) ◽  
pp. 188-204 ◽  
Author(s):  
Shigeyuki Kuwada ◽  
Julia S. Anderson ◽  
Ranjan Batra ◽  
Douglas C. Fitzpatrick ◽  
Natacha Teissier ◽  
...  
Keyword(s):  
Animal Model ◽  
Amplitude Modulation ◽  
Single Unit ◽  
Modulation Frequency ◽  
Multiple Sources ◽  
High Modulation ◽  
Before And After ◽  
Single Unit Recordings ◽  
Composite Response ◽  
The Brain

The scalp-recorded amplitude-modulation following response (AMFR)” is gaining recognition as an objective audiometric tool, but little is known about the neural sources that underlie this potential. We hypothesized, based on our human studies and single-unit recordings in animals, that the scalp-recorded AMFR reflects the interaction of multiple sources. We tested this hypothesis using an animal model, the unanesthetized rabbit. We compared AMFRs recorded from the surface of the brain at different locations and before and after the administration of agents likely to enhance or suppress neural generators. We also recorded AMFRs locally at several stations along the auditory neuraxis. We conclude that the surface-recorded AMFR is indeed a composite response from multiple brain generators. Although the response at any modulation frequency can reflect the activity of more than one generator, the AMFRs to low and high modulation frequencies appear to reflect a strong contribution from cortical and subcortical sources, respectively.

scholarly journals Optical whispering-gallery mode barcodes for high-precision and wide-range temperature measurements

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Jie Liao ◽  
Lan Yang
Keyword(s):  
High Precision ◽  
Dynamic Range ◽  
Single Mode ◽  
Whispering Gallery Mode ◽  
Temperature Measurements ◽  
Laser Source ◽  
Multiple Modes ◽  
Whispering Gallery ◽  
Wide Range ◽  
Thermal Sensing

AbstractTemperature is one of the most fundamental physical properties to characterize various physical, chemical, and biological processes. Even a slight change in temperature could have an impact on the status or dynamics of a system. Thus, there is a great need for high-precision and large-dynamic-range temperature measurements. Conventional temperature sensors encounter difficulties in high-precision thermal sensing on the submicron scale. Recently, optical whispering-gallery mode (WGM) sensors have shown promise for many sensing applications, such as thermal sensing, magnetic detection, and biosensing. However, despite their superior sensitivity, the conventional sensing method for WGM resonators relies on tracking the changes in a single mode, which limits the dynamic range constrained by the laser source that has to be fine-tuned in a timely manner to follow the selected mode during the measurement. Moreover, we cannot derive the actual temperature from the spectrum directly but rather derive a relative temperature change. Here, we demonstrate an optical WGM barcode technique involving simultaneous monitoring of the patterns of multiple modes that can provide a direct temperature readout from the spectrum. The measurement relies on the patterns of multiple modes in the WGM spectrum instead of the changes of a particular mode. It can provide us with more information than the single-mode spectrum, such as the precise measurement of actual temperatures. Leveraging the high sensitivity of WGMs and eliminating the need to monitor particular modes, this work lays the foundation for developing a high-performance temperature sensor with not only superior sensitivity but also a broad dynamic range.

scholarly journals First in-orbit results of the vector magnetic field measurement of the High Precision Magnetometer onboard the China Seismo-Electromagnetic Satellite

2019 ◽  
Vol 71 (1) ◽  
Author(s):  
Bin Zhou ◽  
Bingjun Cheng ◽  
Xiaochen Gou ◽  
Lei Li ◽  
Yiteng Zhang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Precision ◽  
Magnetic Field Measurement ◽  
Vector Data ◽  
Magnetic Field Data ◽  
Night Side ◽  
The Difference ◽  
The Magnetic Field ◽  
Ground Calibration ◽  
Data Calibration

Abstract The High Precision Magnetometer (HPM) is one of the main payloads onboard the China Seismo-Electromagnetic Satellite (CSES). The HPM consists of two Fluxgate Magnetometers (FGM) and the Coupled Dark State Magnetometer (CDSM), and measures the magnetic field from DC to 15 Hz. The FGMs measure the vector components of the magnetic field; while the CDSM detects the magnitude of the magnetic field with higher accuracy, which can be used to calibrate the linear parameters of the FGM. In this paper, brief descriptions of measurement principles and performances of the HPM, ground, and in-orbit calibration results of the FGMs are presented, including the thermal drift and magnetic interferences from the satellite. The HPM in-orbit vector data calibration includes two steps: sensor non-linearity corrections based on on-ground calibration and fluxgate linear parameter calibration based on the CDSM measurements. The calibration results show a reasonably good stability of the linear parameters over time. The difference between the field magnitude calculated from the calibrated FGM components and the magnitude directly measured by the CDSM is just 0.5 nT (1σ) when the linear parameters are fitted separately for the day- and the night-side. Satellite disturbances have been analyzed including soft and hard remanence as well as magnetization of the magnetic torquer, radiation from the Tri-Band Beacon, and interferences from the rotation of the solar wing. A comparison shows consistency between the HPM and SWARM magnetic field data. Observation examples are introduced in the paper, which show that HPM data can be used to survey the global geomagnetic field and monitor the magnetic field disturbances in the ionosphere.

Electrical Discharge Grinding (EDG) of Polycrystalline Diamond - Effect of Machining Polarity

2014 ◽  
Vol 1025-1026 ◽  
pp. 628-632 ◽  
Author(s):  
Mohammad Zulafif Rahim ◽  
Song Lin Ding ◽  
John Mo
Keyword(s):  
Electrical Discharge ◽  
Complex Geometry ◽  
Polycrystalline Diamond ◽  
Machining Process ◽  
Morphological Examination ◽  
Carbon Structure ◽  
Finishing Process ◽  
Advanced Machining ◽  
The Difference ◽  
Pcd Tools

Electrical discharge grinding (EDG) is an advanced machining process and can be utilised to fabricate complex geometry of PCD tools. However, the PCD removal mechanism in this process is complicated. This study was carried out to understand the difference in PCD surface structure with difference EDG polarities. The study revealed that the finishing process with negative polarity is the reason for the porous structure on the surface. Further analysis on the chemical element and carbon structure were implemented as the morphological examination of the surface.

Quantitative FM Spectroscopy at High Temperatures: The Detection of 1CH2 behind Shock Waves

2000 ◽  
Vol 214 (12) ◽  
Author(s):  
G. Friedrichs ◽  
H.Gg. Wagner
Keyword(s):  
High Temperature ◽  
Shock Waves ◽  
High Temperatures ◽  
Frequency Modulation ◽  
Modulation Frequency ◽  
Optical Power ◽  
Time Resolved ◽  
Signal Conversion ◽  
High Modulation ◽  
Singlet Methylene

The technique of time resolved frequency modulation (FM) spectroscopy has been shown to provide a very sensitive means to detect small radicals behind shock waves. Features of high temperature FM spectroscopy behind shock waves will be discussed and a general signal conversion procedure to carry out quantitative concentration measurements will be presented.Using a high modulation frequency, a high modulation index and high total optical power, singlet methylene radicals (α

Research on Key Technology of Data Mining for Volleyball Game Based on Service System

2014 ◽  
Vol 543-547 ◽  
pp. 4698-4701
Author(s):  
Juan Wang
Keyword(s):  
Data Mining ◽  
High Precision ◽  
Service System ◽  
Processing System ◽  
Machining Process ◽  
Precision Machining ◽  
Intelligent Processing ◽  
Mining Model ◽  
Processing Cycle ◽  
Key Parameter

During the processing of aircraft and other high precision machinery workpieces, if using the traditional machining methods, it will consume a amount of machining costs, and the mechanical processing cycle is long. In this context, this paper designs a kind of robot intelligent processing system with high precision machinery. And it has realized the intelligent online control on the machining process by using the high precision machining intelligent online monitoring technology and the numerical simulation prediction technology. Finally, this system is introduced into the process of data mining for volleyball game, and designs the partial differential variational data mining model, which has realized the key parameter data mining of volleyball games service system, and has provided reliable parameters and technical support for the training of volleyball players.

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