A new self-mixing interferometry based on sinusoidal phase modulating technique is presented. Self-mixing interference occurs in the laser cavity by reflecting light from a mirror-like target front of laser. Sinusoidal modulation beam obtained an electro-optic modulator (EOM) external cavity. The signal calculated Fourier analysis method. interferometer applied to measure displacement high-precision commercial PZT with accuracy <10nm. measurement range system mainly depends maximum operating...

A new, to the best of our knowledge, method for measurement absolute distance a remote target based on laser diode self-mixing interferometry is presented. double-modulation technique introduced improve resolution. Wavelength modulation beam obtained by modulating injection current diode. Phase an electro-optic crystal in external cavity. Absolute determined Fourier analysis method. Theoretical and numerical simulations are given. Experimental results show that resolution +/-0.3 mm can be...

In this study, a nano-displacement measurement system is proposed and demonstrated both theoretically experimentally, which was based on modified Mach-Zehnder (M-Z) interferometer using two conjugated orbital angular momentum (OAM) beams. contrast to the previous M-Z-based OAM interferometer, reflection module inserted into reference arm instead of simple mirror. As result, effect transverse position-dependence phase-shift caused by dove prism can be clearly eliminated stable robust...

In this paper, we demonstrated an improved laser self-mixing grating interferometer (SMGI) with auto-collimation design which can avoid the disturbance from light feedback of zero-order diffraction beam. order to obtain higher optical subdivision, SMGI multiple-diffraction is implemented. Both theoretical analysis and experimental work show that proposed system for displacement measurement achieve high sensitivity low uncertainty. Using system, different forms micro-displacement signals...

A self-mixing birefringent dual-frequency laser Doppler velocimeter (SBD-LDV) for high-resolution velocity measurements is presented in this paper. The information of the object can be accurately extracted from frequency shift light-carried microwave signal. We generate a virtual stable by using He-Ne which further simplifies structure light source. Moreover, optical configuration based on interference brings benefits compact setup, self-alignment, and direction discriminability....

We fabricate and experimentally demonstrate a hybrid structured in-line Mach-Zehnder interferometer (MZI) for simultaneous measurement of refractive index (RI) temperature. The MZI is composed an embedded slender air cavity in micro fiber cascaded to piece photonic crystal (PCF). fabricated by fusion splicing fused tapering. interference spectra based on the PCF can be extracted through low-pass band-pass filters, respectively. RI temperature are interrogated coefficient matrix...

Abstract Orbital‐angular‐momentum (OAM) beams‐based interferometer has been found various applications in high‐precision metrology. However, most of its reported to date are limited 1D ones, and the simultaneous measurements for multidimensional displacement have rarely explored. Here an angular momentum superposition is first proposed demonstrated, which phases‐changes induced by rotational linear displacements, independently carried (SOAMS) beam containing different spin orbital momenta,...

This paper studied a multi-channel self-mixing interferometric vibration measurement system based on vertical-cavity surface-emitting laser array. A 1 × 8 array was utilized to irradiate multiple positions of vibrating target establish independent channels. The reflected light beams, carrying the information each position, were redirected back into and coherently mixed with original optical field, generating interference. signals measured by monitoring junction voltage variations across...

The continuous development of urban rail transit networks has highlighted the mismatch between passenger demand and transportation capacity, necessitating more flexible organization models. To achieve a agile train operation organization, this paper employs “virtual grouping” technology to reduce running intervals increase density, thereby maximizing line enhancing service level transit, facilitating greater flexibility in various modes, such as long short routes, fast slow trains, Y-shaped...

A novel single-feed dual-band dual-mode and dual-polarized microstrip antenna based on metamaterial structure is proposed. The composite right/left-handed transmission line (CRLH TL) theory used to design this antenna. Dual-mode can be obtained by exciting the with a monopolar radiation in n = 0 mode patch-like pattern +1 mode, respectively. As geometry of radiating patch does not affect infinite wavelength circular polarization (CP) for truncating square linear (LP) staying unchangeable....

An in-fiber Bragg grating (FBG) sensor for refractive index (RI) measurement is proposed and experimentally demonstrated by using an optoelectronic oscillator (OEO). The device etched phase-shifted fiber (PS-FBG) with a radius of 27.5 μm. In the OEO loop, PS-FBG exposed to different liquid samples via evanescent field interaction guided mode. Since RI change can introduce shift center wavelength PS-FBG, frequency will change. Therefore, variation ambient be estimated measuring oscillating...

A new signal-processing method based on an electronic frequency down-conversion technique has been introduced into a sinusoidal phase-modulating, self-mixing interferometer. The developed interferometer employs electro-optical crystal placed in the external cavity of He–Ne laser to generate phase modulation with high rate and ultralow insertion loss. Phase quadrature signals which have amplitude-modulated by sine cosine functions, respectively, measured displacement can be extracted from...

A simple and robust testing system based on a laser self-mixing grating interferometer (SMGI) is proposed to determine the sensitivity of accelerometers. Self-mixing interference occurs when light emitted from diode incident onto reflective at fixed angle first-order diffracted returns back into cavity. Frequency ratio method minimum point that are officially used calibrate accelerometers modified make it suitable an SMGI system. In order evaluate performance method, commercial...

In this letter, we proposed an innovative laser self-mixing interferometer (SMI) with a reflection-type two-dimensional (2D) grating for three-dimensional (3D) dynamic displacement sensing. When the beams emitted by three lasers are incident on reflective 2D auto-collimation diffraction angles, diffracted will return into along original path, thus generating interference effect in each laser. order to obtain higher measurement resolution, phase-modulation technique is applied interferometer....

In this paper, a novel self-mixing grating interferometer (SMGI) with dual laser diodes (LDs) is proposed for 2-D dynamic displacement measurement. The light beams emitted from the LDs are incident onto reflection ±1st order auto-collimation diffraction angles and then diffracted back into lasers, respectively, which can cause interference effect in each LD. Theoretical analysis on SMGI signals corresponding to presented verified experimental observations. Measurement results of demonstrate...

A novel laser feedback grating interferometer (LFGI) with a phase-generated carrier demodulation technique is proposed in this paper. Laser interference occurs when light emitted from diffracted by the double-diffraction system and re-enters active cavity, thus generating modulation of lasing field. In order to improve displacement measurement resolution, phase introduced an electro-optic modulator external cavity LFGI. Detection can be easily achieved time-domain orthogonal demodulation,...

Abstract A microstrip circular patch antenna with multi-band multi-mode function is presented in this paper. Metamaterial structures including four curved lines added around the radiating and a ring of modified mushroom cells loaded under enable property. Two monopole modes omnidirectional radiation patterns azimutal plane one mode patch-like pattern between them are excited by single probe feed for novel antenna. prototype was designed fabricated verification. Both simulation measurement...

A sinusoidal phase-modulating He-Ne laser subject to weak optical feedback has been used develop an interferometer that is capable of performing real-time displacement measurement with nanometer accuracy. The principle and the signal processing method are introduced. commercial dual-frequency included in both small large ranges evaluate performance developed interferometer. Experimental results show average errors standard deviations good agreement data obtained from resolution multiple...

By combining the principles of sinusoidal phase-shifting technique and self-mixing interferometry, a novel instrument has been developed for real-time displacement measurement with nanometer accuracy. The phase shifting is introduced by an electro-optic modulator object measured analyzing harmonic components in interference signal during each period. Theoretical analysis simulation results are presented some error sources discussed detail. experiments using high precision nano-positioning...