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![A block diagram of the optical heterodyne detection setup for surface roughness measurement. Inset shows the beam configuration on the mirror surface [21].](publication/290738036/figure/fig7/AS:668920780451861@1536494550670/A-block-diagram-of-the-optical-heterodyne-detection-setup-for-surface-roughness.png)
A block diagram of the optical heterodyne detection setup for surface roughness measurement. Inset shows the beam configuration on the mirror surface [21].
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![Figure 4. Block diagram of the fluorescence lifetime sensing setup [22].](publication/290738036/figure/fig4/AS:668920780423200@1536494550573/Block-diagram-of-the-fluorescence-lifetime-sensing-setup-22_Q320.jpg)
Optical metrology techniques used to measure changes in thickness; temperature and refractive index are surveyed. Optical heterodyne detection principle and its applications for precision measurements of changes in thickness and temperature are discussed. Theoretical formulations are developed to estimate crystal growth rate, surface roughness and...
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Context 1
... rf wave was generated by mixing the optical waves (10% of the laser power) in a detector. Measurement rf wave was generated by launching the beams to an air-lifted mirror that can be rotated (Figure 8). The p-and s-polarization components are spatially separated by a Wollaston prism and focused at two different points on the air-lifted mirror (inset of Figure 8). ...
Context 2
... rf wave was generated by launching the beams to an air-lifted mirror that can be rotated (Figure 8). The p-and s-polarization components are spatially separated by a Wollaston prism and focused at two different points on the air-lifted mirror (inset of Figure 8). One of the spots is incident at a point that is coincident with the axis of rotation. ...
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Citations
... There are several methods for measuring sugar concentration, such as refractometers, specific gravity meters, electronic tongues, and high-pressure liquid chromatography [1][2][3][4], which are commonly used for determining the sugar content and sweetness of fruits and vegetables. Chromatographic techniques are highly accurate, but their extensive sample preparation involving solvent extraction makes them less popular. ...
This study aims to develop a low-cost refractometer for measuring the sucrose content of fruit juice, which is an important factor affecting human health. While laboratory-grade refractometers are expensive and unsuitable for personal use, existing low-cost commercial options lack stability and accuracy. To address this gap, we propose a refractometer that replaces the expensive CCD sensor and light source with a conventional LED and a reasonably priced CMOS sensor. By analyzing the output waveform pattern of the CMOS sensor, we achieve high precision with a personal-use-appropriate accuracy of 0.1%. We tested the proposed refractometer by conducting 100 repeated measurements on various fruit juice samples, and the results demonstrate its reliability and consistency. Running on a 48 MHz ARM processor, the algorithm can acquire data within 0.2 seconds. Our low-cost refractometer is suitable for personal health management and small-scale production, providing an affordable and reliable method for measuring sucrose concentration in fruit juice. It improves upon the existing low-cost options by offering better stability and accuracy. This accessible tool has potential applications in optimizing the sucrose content of fruit juice for better health and quality control.
... Conventional interferometric configurations using a monochromatic or white light design such as Michelson [14][15][16], Twyman-Green [17][18][19], Fabry-Perot [20], Fizeau [19,21] are some of the typical arrangements used for surface profiling [22][23][24][25][26] and measuring the phase variations over the sample. In Michelson, Mach-Zehnder [16] and Linnik configurations [27,28], the object and the reference beams travel along paths that are not common to both the interfering beams resulting in the necessity of vibration isolation platforms. ...
... Conventional interferometric configurations using a monochromatic or white light design such as Michelson [14][15][16], Twyman-Green [17][18][19], Fabry-Perot [20], Fizeau [19,21] are some of the typical arrangements used for surface profiling [22][23][24][25][26] and measuring the phase variations over the sample. In Michelson, Mach-Zehnder [16] and Linnik configurations [27,28], the object and the reference beams travel along paths that are not common to both the interfering beams resulting in the necessity of vibration isolation platforms. This is all the more applicable to methods of temporal phase shifting interferometry (PSI) [29][30][31][32][33] which require stringent isolation from ambient disturbances. ...
This work describes a full-field and near-common-path in-line laser interferometer and interferometric microscope utilizing a wire-grid polarizer (WGP) placed normally on the laser beam illuminating the sample. The WGP serves the dual purpose of a beam splitter and a polarization separator where the reference and sample beams reflected and transmitted from it respectively are orthogonally polarized so that, unlike other conventional interferometers, polarization phase shifting is inherent in its architecture. This arrangement presents experimental results showing quantitative phase analysis of transparent and reflecting phase samples
... Indeed, interferometers have proven to be a very powerful tool to measure small changes in the optical properties of a material (e.g. refractive index) [100]. In this section, we explain the working principle of interferometers in general and the procedure for developing Mach-Zehnder interferometer. ...
Planar symmetry makes integrated photonics (IP) waveguides linear birefringent; they support only two linearly polarized eigenmodes, namely the transverse electric (TE) and transverse magnetic (TM) modes. Because of the linear birefringence (LB), except for TE and TM, the polarization state of the guided light in IP is not conserved. Therefore, any application that requires other polarizations, such as circular polarization (the key polarization in chiral sensing), cannot take advantage of IP technology. One way to overcome the limitation of LB in optical waveguides is to use waveguides made of chiral materials, known as chirowaveguides. In this thesis, we report on the realization of channel optical chirowaveguides that can be used for polarization applications other than TE/TM, in particular for circular polarization applications. The channel waveguides are designed based on our theoretical study on polarization properties of chirowaveguides and numerical simulations of the birefringence behavior of channel waveguides. The sol-gel method is used to make transparent chiral organically modified silica (ORMOSIL) layers with high circular birefringence and controlled optical quality, refractive index and thickness. Then, by making PDMS molds and imprinting them on the gel form of ORMOSIL layers, channel waveguides of different sizes are fabricated. By combining the high circular birefringence of our material with the size-modulated LB of the fabricated channel chirowaveguides, we obtained chirowaveguides having linear to quasi-circular eigenmodes. Indeed, the chirowaveguides with quasi-circular eigenmodes can be used for quasi-circular and circular polarization applications in IP technology, as miniaturized chirality sensors for pharmacology, medicine, food industry or environmental pollution measurement.
... Interferometry has been used in nanoscience and technology for very sensitive measurements because of its in-situ, non-contact, and non-destructive nature. It has also been used to monitor pressure [64], temperature [65], gas concentrations [66], refractive index (RI) [67], crystallisation growth rate [68], vibration [69], surface profile [70], and bio-sensing [71]. Moreover, this technique is used to identify VOCs by measuring modifications in sensing materials, most often films made of micro-porous silicates or polymers which are chosen based on the intended target molecules. ...
Volatile organic compounds (VOCs) are organic chemicals that are toxic and detrimental to the human body and the environment. Therefore, a great mandate for the selective as well as sensitive recognition of VOCs, process control, environmental monitoring, and medical diagnosis is necessary. In the last few years, various forms of nanomaterials have been explored for gas and VOCs sensing with the detection on the miniaturized scale using various sensing approaches including optical, chemiresistive, and electrochemical techniques. Two-dimensional (2D) materials have received tremendous attention owing to their unique structure and extraordinary physical as well as chemical properties which make them an attractive platform for numerous applications including electronics, optoelectronics, energy storage and conversion, catalysis, and chemical sensors. 2D-materials offer unique sensing properties with extremely high sensitivity which is particularly important for the detection of toxic pollutants such as nitrogen dioxide (NO2) and toxic VOCs such as benzene and formaldehyde. This review emphasizes the state-of-the-art recent developments in synthesis, VOCs sensing performance and sensing mechanism of numerous 2D-materials including graphene, graphene oxide (GO), graphene nanoplatelets (Gr-NPls), graphene nanosheets (GNs), transition metal dichalcogenides (TMDs), hexagonal boron nitride (h-BN), MXenes, black phosphorus (BP) and graphdiyne etc. A brief descriptions of various synthesis approaches of 2D materials are given along with their fundamental VOCs sensing mechanisms. Finally, the performances of various 2D-materials derived VOC sensors are summarized.
... Optical interferometry is an established method that has achieved high-accuracy measurements in a variety of applications such as temperature and pressure measurement, refractive index measurement, growth rate in crystallization and surface metrology [64,65]. Two-beam amplitude-division interferometry is commonly used for sensing applications and can be described as an interference pattern produced by the recombination of two light beams of the same frequency, constant phase difference and identical direction [66]. ...
A range of optical fibre-based sensors for the measurement of ethanol, primarily in aqueous solution, have been developed and are reviewed here. The sensing approaches can be classified into four groups according to the measurement techniques used, namely absorption (or absorbance), external interferometric, internal fibre grating and plasmonic sensing. The sensors within these groupings can be compared in terms of their characteristic performance indicators, which include sensitivity, resolution and measurement range. Here, particular attention is paid to the potential application areas of these sensors as ethanol production is globally viewed as an important industrial activity. Potential industrial applications are highlighted in the context of the emergence of the internet of things (IoT), which is driving widespread utilization of these sensors in the commercially significant industrial and medical sectors. The review concludes with a summary of the current status and future prospects of optical fibre ethanol sensors for industrial use.
... Due to the presence of density gradients, compressible fluid flow is very suitable for an investigation using optical methods that are sensitive either to the refractive index of the medium through which the light wave propagates (interferometry), or to a refractive index gradient in the medium (schlieren [7][8][9][10][11], shadowgraph [12][13][14][15][16], Moiré deflectometry [17][18][19][20][21]). Interferometric methods such as classical interferometry [22,23], holographic interferometry [24] and digital holographic interferometry [25][26][27][28][29] stand as the most accurate optical techniques [26,30,31] that are applied in many sectors of industry and scientific research, notably in the study of liquid cooling [32], diffusion [33], convection [34,35], temperature measurements and visualization [1,25,36], temperature fields measurement in pulsatile jets [25], studies of living cell imaging [37,38], precision measurement [15,39,40], vibrometry [41,42] etc. ...
This paper presents a very effective interference technique for the sensing and researching of compressible fluid flow in a wind tunnel facility. The developed technique is very sensitive and accurate, yet easy to use under conditions typical for aerodynamic labs, and will be used for the nonintrusive investigation of flutter in blade cascades. The interferometer employs a high-speed camera, fiber optics, and available “of-the-shelf” optics and optomechanics. The construction of the interferometer together with the fiber optics ensures the high compactness and portability of the system. Moreover, single-shot quantitative data processing based on introducing a spatial carrier frequency and Fourier analysis allows for almost real-time quantitative processing. As a validation case, the interferometric system was successfully applied in the research of supersonic compressible fluid discharge from a narrow channel in a wind tunnel. Density distributions were quantitatively analyzed with the spatial resolution of about 50 μm. The results of the measurement revealed important features of the flow pattern. Moreover, the measurement results were compared with Computational Fluid Dynamics (CFD) simulations with a good agreement.
... The optical film interferometry technique employed to measure lubricant film thickness formation in a rolling ballon-flat contact which was originally described by Luo et al. [32][33][34] was used. The full view of the optical interferometry film thickness in EHL point contact apparatus setup used, is shown in Figure 3. ...
... There is a vast field of applications of DHI and other interference based methods including: entertainment display [8], imaging heat transfer and mass transfer [7,[9][10][11][12][13], research in free convection [14,15], visualization of the 3D velocity vector field in turbulent boundary layer [6], analysis of supersonic jets [6], biological (living cell imaging) [6,16], environmental applications [6,17], precision measurements [8,18,19], small displacements [20], ...
In this paper, we present a method of quantitatively measuring in real-time the dynamic temperature field change and visualization of volumetric temperature fields generated by a 2D axial-symmetric heated fluid from a pulsatile jet in a water tank through off-axis digital holographic interferometry. A Mach-Zehnder interferometer on portable platform was built for the experimental investigation. The pulsatile jet was submerged in a water tank and fed with water with higher temperature. Tomographic approach was used to reconstruct the temperature fields through the Abel Transform and the filtered back-projection. Averaged results, tomographic view, standard deviation and errors are presented. The presented results reveal digital holographic interferometry as a powerful technique to visualize temperature fields in flowing liquids and gases.
... Optical interferometry is an established method that has achieved high-accuracy measurements in a variety of applications such as temperature and pressure measurement, refractive index measurement, growth rate in crystallization and surface metrology [64,65]. Two-beam amplitude-division interferometry is commonly used for sensing applications and can be described as an interference pattern produced by the recombination of two light beams of the same frequency, constant phase difference and identical direction [66]. ...
A U-bend POF Sensor is a potential solution for real-time monitoring of the production of biofuels, such as bioethanol even at the very low-level initial concentration of product which can occur during the initial production stage via recombinant Cyanobacteria strains such as Synechocystis PCC6803. The sensor demonstrates excellent repeatability and standard deviation of only ±0.001945 O.D per 10−7 RIU.
... Interferometers are classified, according to the number of overlapping optical beams, into two-beam or multiple-beam devices. The most common interferometers are the Fizeau, the Michelson, the Mach -Zehnder and the Sagnac interferometers, while the most well-known multi-beam device is the Fabry-Perot interferometer [3][4]. Optic fiber interferometric sensors have been used in wide practical applications such as monitoring of mechanical deformation of aircrafts, bridges. ...
... Optic fiber interferometric sensors have been used in wide practical applications such as monitoring of mechanical deformation of aircrafts, bridges. and buildings, as well as biomedical sensitization to health monitoring systems [4]. Optical fiber was used as a sensor through a heterodyne detection technique, which depends on optical interference of pressure sensing, stress, temperature, rotation, velocity measurement of particles, as well as sensitivity in the electrical and magnetic fields [5][6][7][8]. ...
... The optical interference spectrum can be described as a modified intensity based on the wavelength of the optical spectrum and the result of the phase differences between the optical beams. The peaks of the modified spectrum mean that beams are in phase and out-of-phase, in the modulus of 2 [4]. Since the interferometers give a lot of temporal and spectral information as their beams, the measurement can be determined by various changes in the wavelength, intensity, frequency, phase and so on. ...
The production and analysis of an optimal interference pattern for the optical fiber interferometer of a 193.1THz continuous laser source was simulated by comparing the spectral spectroscopy of the two arms of interferometer to be used as a heterodyne detection in sensing the body range, speed, and direction of movement by delaying the time between the arms. The study showed that the fringe pattern can be sensed a range by the free spectral range FSR and the velocity by the fringe separation FS and the direction by the fringe spatial frequency FSF.
