Interferograms Research Articles

Entangling entanglement: coupling frequency and polarization of biphotons on demand

Quantum information is often carried in the frequency and polarization degrees of freedom (DoFs) in single photons and entangled photons. We demonstrate an approach to couple and decouple the frequency and polarization DoFs of broadband biphotons. Our approach is based on a nonlinear interferometer consisting of a linear dispersive medium and a polarization controller in between the two biphoton sources (nonlinear media). When the two DoFs are decoupled, maximally polarization-entangled biphotons are observed in the polarization DoF, while interference fringes are observed in the spectrum of the biphotons. When the two DoFs are coupled, by adjusting the polarization controller, interference fringes disappear from the spectrum and instead appear in the degree of polarization entanglement, varying between 0 and 1, depending on the signal and idler frequencies. Our approach offers a convenient means of tuning the polarization entanglement and can be employed for arbitrary biphoton polarization state generation.

Understanding the effects of microbubble concentration on localization accuracy in super-resolution ultrasound imaging.

Super-Resolution Ultrasound (SRUS) through localising and tracking of Microbubbles (MBs) can achieve sub-wavelength resolution for imaging microvascular structure and flow dynamics in deep tissue in-vivo. The technique assumes that signals from individual MBs can be isolated and localised accurately, but this assumption starts to break down when the MB concentration increases and the signals from neighbouring MBs start to interfere. The aim of this study is to gain understanding of the effect of MB-MB distance on ultrasound images and their localisation. Ultrasound images of two MBs approaching each other were synthesised by simulating both ultrasound field propagation and nonlinear MB dynamics. Besides the distance between MBs, a range of other influencing factors including MB size, ultrasound frequency, transmit pulse sequence, pulse amplitude and localisation methods were studied. The results show that as two MBs approach each other, the interference fringes can lead to significant and oscillating localisation errors, which are affected by both the MB and imaging parameters. When modelling a clinical linear array probe operating at 6MHz, localisation errors between 20 to 30 µm (∼1/10th wavelength) can be generated when MBs are ∼ 500µm (2 wavelengths or ∼ 1.7 times the Point Spread Function (PSF)) away from each other. When modelling a cardiac probe operating at 1.5 MHz, the localisation errors were as high as 200 µm (∼1/5th wavelength) even when the MBs were more than 10 wavelengths apart (2.9 times the PSF). For both frequencies, at smaller separation distances, the two MBs were misinterpreted as one MB located in between the two true positions. Cross-correlation or Gaussian fitting methods were found to generate slightly smaller localisation errors than centroiding. In conclusion, caution should be taken when generating and interpreting SRUS images obtained using high agent concentration with MBs separated by less than 1.7 to 3 times the PSF, as significant localisation errors can be generated due to interference between neighbouring MBs.

A novel hybrid model based on integrating RGB and YCrCb color spaces for demodulating the phase map of fibres using a color phase-shifting profilometry technique

In this paper, a refined color phase- shifting profilometry technique is suggested for accurate examining of the phase and optical features of polymeric fibres. It is based on combining the RGB and the YCrCb color spaces. The primary components of the suggested model (RGCb) are red (R), green (G), and blue chrominance (Cb). This model is considered an early study in combining color spaces to demodulate the phase map of the tested fibre. The suggested model enhances affects that arise from color crosstalk and chromatic aberration, especially in the blue color channel. The Pluta polarizing interference microscope is utilised for capturing RGB interference fringe pattern for polypropylene (PP) fibre. The wrapped and unwrapped phase maps of this fibre are demodulated via the traditional, the corrected RGB color phase shifting algorithms and the suggested RGCb model. For evaluating the accuracy of the suggested model, the contour line method is used. The obtained results confirm that the demodulated phase using the suggested RGCb model has the least standard deviation from the reference phase value compared to the other two algorithms. The validation of the suggested model for investigating the optical properties of drawn fibres with a high order of fringe shift is checked. Based on the demodulated phase maps from the suggested model, the 2.5D birefringence profile of a PP fibre is examined.

Incident angle optimization with multiple conflicting objectives based on BP-MOPSO in oblique laser interferometry

The oblique incident phase-shifting interferometric measurement method is an effective technique for assessing gear tooth form deviation. In the measurement process, the tooth flank incident angle is a crucial factor determining the quality of interferograms. Addressing the challenge in traditional optical path design, where the selection of the tooth flank incident angle encounters a trade-off among quality features such as measurable tooth area (MTA), interference fringe density (IFD) and interferogram compression ratio (ICR), this paper proposes an optimized method for the tooth flank incident angle. Firstly, a comprehensive evaluation model is established to calculate and analyze the MTA, IFD and ICR of the helical gear. Secondly, by integrating BP neural network and Multi-Objective Particle Swarm Optimization (MOPSO) algorithm, a tooth flank incident angle optimization method is devised to simultaneously optimize the measurement light incident angle γ and the rotation angle of the gear axis β. Finally, simulation analyses and physical experiments are employed to demonstrate the feasibility of the proposed method, compared to before optimization, the pseudocorrelation (PSD) value has increased by an average of 34%, and the residual points have decreased by an average of 80%, confirming its capability to improve quality interferogram and measurement accuracy.

Measurements of the geometrical characteristics and refractive index of specimens made with X-ray interferometers

The theoretical background to the formation of interference fringes in a triple Laue X-ray interferometer by a specimen having plano-concave form is presented. The interference fringes in the general case have an elliptical form. The relation between the radius of the specimen, the refractive index and the radii of the interference fringes is established. For two epoxy lenses having different radii, the interference fringes are registered. The refractive index and the radii are determined by measuring the radii of the obtained interference fringes.

Gravito-diamagnetic forces for mass independent large spatial superpositions

Abstract Creating a massive spatial quantum superposition, such as the Schrödinger cat state, where the mass and the superposition size within the range 10-19 - 10-14 kg and Δx ∼ 10 nm - 100 μm, is a challenging task. The methods employed so far rely either on wavepacket expansion or on a quantum ancilla, e.g. single spin dependent forces, which scale inversely with mass. In this paper, we present a novel approach that combines gravitational acceleration and diamagnetic repulsion to generate a large spatial superposition in a relatively short time. After first creating a modest initial spatial superposition of 1 µm, achieved through techniques such as the Stern-Gerlach (SG) apparatus, we will show that we can achieve an ∼ 102 - 103 fold improvement to the spatial superposition size (1 µm → 980 µm) between the wave packets in less than 0.02 s by using the Earth’s gravitational acceleration and then the diamagnetic repulsive scattering of the nanocrystal, neither of which depend on the object mass. Finally, the wave packet trajectories can be closed so that spatial interference fringes can be observed. Our findings highlight the potential of combining gravitational acceleration and diamagnetic repulsion to create and manipulate large spatial superpositions, offering new insights into creating macroscopic quantum superpositions.

The Theory of Absoluteness —The Relations among Matter, Space, Time and Motion

In this paper, the absolute static reference frame of the universe is established, the Galileo's relativity principle and the essence of light are analyzed, and the zero result of Michelson-Morey experiment is re-recognized. The conclusion is that the light in two directions reaches the eyepiece at the same time, and when the interferometer is rotated at any angle, the light in two directions still reaches the eyepiece at the same time, and the interference fringes will not move, so the zero result of the experiment is inevitable. This paper analyzes Lorenz's explanation of the zero result of the Michelson-Morey experiment, and points out that there are many contradictions and mistakes in it. Michelson confused the reference frame in his analysis and calculation, and the result was necessarily wrong. The Michelson-Morey experiment wants to measure the speed of the earth relative to the "ether" on the earth. According to the Galileo's relativity principle, it is impossible to measure it. This experiment is meaningless. Because Michelson's wrong calculation result is not consistent with the zero result of the experiment, Lorenz had to set up "length shortening", "clock slowing down" and a Lorenz transformation factor to piece together the zero result of the experiment.It is precisely because these assumptions are incorrect that all the relations and related theories that use Lorentz transformation factors are incorrect, and the special theory of relativity is completely wrong. Only the Galileo's relativity principle can correctly explain the zero result of Michelson-Morey experiment, and the Galileo’s transformation is the correct theory to describes motion. This paper also re-understands the relations among matter, space, time, motion, inertia, field, field wave, force and energy, analyzes the essence of nuclear energy, and establishes a new model of the universe. It makes physics return to the correct track of classical theory and deepens and develops classical theory.

The Theory of Absoluteness —The Relations among Matter, Space, Time and Motion

In this paper, the absolute static reference frame of the universe is established, the Galileo's relativity principle and the essence of light are analyzed, and the zero result of Michelson-Morey experiment is re-recognized. The conclusion is that the light in two directions reaches the eyepiece at the same time, and when the interferometer is rotated at any angle, the light in two directions still reaches the eyepiece at the same time, and the interference fringes will not move, so the zero result of the experiment is inevitable. This paper analyzes Lorenz's explanation of the zero result of the Michelson-Morey experiment, and points out that there are many contradictions and mistakes in it. Michelson confused the reference frame in his analysis and calculation, and the result was necessarily wrong. The Michelson-Morey experiment wants to measure the speed of the earth relative to the "ether" on the earth. According to the Galileo's relativity principle, it is impossible to measure it. This experiment is meaningless. Because Michelson's wrong calculation result is not consistent with the zero result of the experiment, Lorenz had to set up "length shortening", "clock slowing down" and a Lorenz transformation factor to piece together the zero result of the experiment.It is precisely because these assumptions are incorrect that all the relations and related theories that use Lorentz transformation factors are incorrect, and the special theory of relativity is completely wrong. Only the Galileo's relativity principle can correctly explain the zero result of Michelson-Morey experiment, and the Galileo’s transformation is the correct theory to describes motion. This paper also re-understands the relations among matter, space, time, motion, inertia, field, field wave, force and energy, analyzes the essence of nuclear energy, and establishes a new model of the universe. It makes physics return to the correct track of classical theory and deepens and develops classical theory

Analysis and simulation of the effect of large optical range difference of common path coherent-dispersion spectrometer on the detection of exoplanet radial velocities

The Exoplanet Explorer common-path coherent-dispersion spectrometer (CODES) utilizes a unique combination of an asymmetric common path Sagnac interferometer and a low to medium resolution spectrometer. The ideal optical range difference (OPD) interval for CODES is OPD ∈ {15.06 mm, 19.45 mm}; however, the OPD of CODES is 64.3 mm to achieve better detection accuracy. Though they will increase the accuracy of detection, large OPDs outside of the ideal interval will also reduce the contrast of the interference fringes, making phase changes more hazy. This may also significantly affect the radial velocity inversion and reduce CODES's instrumental accuracy. This study creates an inverse tone mapping operator based on the photographic model and designs an inverse tone mapping algorithm called CODESCE. The outcomes of the experiments demonstrate that the tone mapping algorithm CODESCE in this work is appropriate for enhancing the contrast of interference fringe images with high OPD, and it can enhance the contrast of interference fringes by three orders of magnitude when OPD = 64.3 mm; the processed interference fringes are located in the range of interference fringe curves of the optimal OPD. By comparison with other current approaches, the suggested algorithm yields superior processing outcomes.

High-Sensitivity Polarization Sensitive Optical Coherence Tomography Based on Numerical Correction for Perfect Circularly Polarized Light

Polarization sensitive optical coherence tomography (PSOCT) makes use of the birefringence information of the sample to compensate for the lack of internal tissue-specific contrast in conventional optical coherence tomography (OCT). Circularly polarized light is always used as an incident beam in PSOCT, but it is difficult to have perfect in practice. The manual calibration method of circularly polarized light suffers from the problems of complicated calibration operation and lack of stability. This study proposes a simple method to enhance the imaging of PSOCT without altering the system. A numerical calibration of circularly polarized light can be implemented using the original system setup, ensuring that the system’s complexity remains unchanged. Enhancements in imaging quality can be achieved through an algorithmic analysis of the captured interference fringe data. This calibration is applied in the field map of interference data before being quadrature-assembled. Notably, the proposed approach achieves high sensitivity in PSOCT. The birefringence image shows a more obvious layered structure. Improvements in the signal-to-noise ratio (SNR) were demonstrated for chicken breast, pork, and beef imaging at about 20 dB.

Analysis of Polarization Angle on Holographic Recording Based on PQ/PMMA.

The polarization state of light waves significantly affects the quality of holographic recordings. This paper quantitatively analyzes the impact of different polarization states of signal and reference beams on the quality of holographic recordings in PQ/PMMA photopolymer systems during the holography process. By deriving the light field distribution of the interference between two light waves of different polarization states and introducing the interference fringe contrast and the modulation of the refractive index of the photopolymer, we established the relationship between the diffraction efficiency of PQ/PMMA photopolymer holographic gratings and the angle between polarization directions. Based on this relationship, simulations and experiments were conducted. The experimental results demonstrated that as the angle between the polarization directions increased, the diffraction efficiency of the material decreased, with the efficiency dropping to 24.69% of its original value when the angle increased from 0° to 50°. When the angle increased to 60°, the influence of polarization characteristics became gradually significant, and at 90°, it was entirely dominated by polarization characteristics. The photoinduced birefringence properties of the PQ/PMMA prepared in the measurement experiment were studied, and the polarization characteristics of the reconstructed light under polarization direction angles of 0°, 60°, and 90° were investigated. The results indicated that at a polarization direction angle of 60 degrees, the material exhibited a significant response to the polarization information of the signal light. Finally, holographic recordings of objects at different polarization direction angles were conducted, and the reconstructed images were used to visually reflect the impact of the polarization direction angle on the quality of holographic recordings.

Experiment and analysis of state preparation for atom interferometry

The state preparation is a crucial procedure in atom interferometry; however, there is a shortage of detailed experimental studies on determining the optimal method for achieving this. This paper investigates and compares two methods for state preparation: the combined use of microwave and Raman light (M-R) and the combined use of optical pumping, microwave, and Raman light (O-M-W). The experimental results demonstrate that the M-R method improves the efficiency of Raman transitions for atom interference, which is helpful in enhancing the contrast of the interference fringes. The O-M-R method increases the quantity of prepared atoms, thereby enhancing the signal-to-noise ratio of the detected signals. This work helps provide a useful experimental basis and reference for researchers to design a suitable state preparation scheme.

Pockels Effect of Interfacial Water on a Mono-Electrode Induced by Current Parallel to the Electrode Surface

When an electric field is applied between two electrodes facing each other immersed in a liquid, the interfacial Pockels effect, a refractive index change proportional to the electric field, occurs in the electric double layer at the liquid–electrode interface. Here, we report that the Pockels effect of interfacial water can be observed even when an electric field is applied parallel to the surface of a “single” electrode in an electrolyte solution. This is a non-trivial result since the electric field parallel to the interface should not cause a broken spatial inversion symmetry, which is required for the Pockels effect. The Pockels signal was detected as a change in the transmitted light intensity due to the field-induced spectral shift of the interference fringes of the transparent conductive oxide electrode layer on a glass substrate. The magnitude of the signal increased as it approached the ends of the electrode, and the sign reversed across the center of the electrode. The electric field distribution calculated from the interfacial potential difference due to the in-plane parallel current showed that an electric field perpendicular to the interface was induced, whose distribution was consistent with the position dependence of the Pockels signal. A similar phenomenon was also observed for a single copper electrode, confirming that this is a universal effect.

A Deep Learning-Based Preprocessing Method for Single Interferometric Fringe Patterns

A novel preprocessing method based on a modified U-NET is proposed for single interference fringes. The framework is constructed by introducing spatial attention and channel attention modules to optimize performance. In this process, interferometric fringe maps with an added background intensity, fringe amplitude, and ambient noise are used as the input to the network, which outputs fringe maps in an ideal state. Simulated and experimental results demonstrated that this technique can preprocess single interference fringes in ~1 microsecond. The quality of the results was further evaluated using the root mean square error, peak signal-to-noise ratio, structural similarity, and equivalent number of views. The proposed method outperformed U-NET, U-NET++, and other conventional algorithms as measured by each of these metrics. In addition, the model produced high-quality normalized fringes by combining objective data with visual effects, significantly improving the accuracy of the phase solutions for single interference fringes.

Athermal phosphate glass matrix at room temperature investigated by thermal lens

The effects of substitution of Al2O3 by K2O in the raw materials for preparing phosphate glasses have been investigated using interferometer and thermal lens techniques. When the K2O content reaches ∼9 wt%, both techniques present an athermal behavior, with a temperature coefficient of the optical path ds/dT equal to zero. From the interferometer measurements, a linear shift of the long period in the interference fringe from 77 K to room temperature was observed, whose athermal temperature is described by the linear function AT=145+246⋅X. Furthermore, when applying thermal lens measurements at room temperature, it was found that there is a range of K2O concentration within the P2O5–Al2O3–Na2O–K2O glass system that becomes athermal. It was also observed that two glasses of the set exhibit athermality three times greater compared to the commercial athermal glass Q98, in terms of the parameter CTL (proportional do ds/dT) obtained from the thermal Lens.

Smart polarization and spectroscopic holography for real-time microplastics identification

Optical microscopy technologies as prominent imaging methods can offer rapid, non-destructive, non-invasive detection, quantification, and characterization of tiny particles. However, optical systems generally incorporate spectroscopy and chromatography for precise material determination, which are usually time-consuming and labor-intensive. Here, we design a polarization and spectroscopic holography to automatically analyze the molecular structure and composition, namely smart polarization and spectroscopic holography (SPLASH). This smart approach improves the evaluation performance by integrating multi-dimensional features, thereby enabling highly accurate and efficient identification. It simultaneously captures the polarization states-related, holographic, and texture features as spectroscopy, without the physical implementation of a spectroscopic system. By leveraging a Stokes polarization mask (SPM), SPLASH achieves simultaneous imaging of four polarization states. Its effectiveness has been demonstrated in the application of microplastics (MP) identification. With machine learning methods, such as ensemble subspace discriminant classifier, k-nearest neighbors classifier, and support vector machine, SPLASH depicts MPs with anisotropy, interference fringes, refractive index, and morphological characteristics and performs explicit discrimination with over 0.8 in value of area under the curve and less than 0.05 variance. This technique is a promising tool for addressing the increasing public concerning issues in MP pollution assessment, MP source identification, and long-term water pollution monitoring.

Upconversion Photonic Doppler Velocimetry Based on Stimulated Brillouin Scattering

Optical up-conversion photonic Doppler velocimetry (PDV) based on stimulated Brillouin Scattering (SBS) with an all-fiber link structure is proposed in this article. Because SBS limits the laser power transmitted by a fiber over long distances, the probe does not have enough outgoing light to reach the measured surface and cannot receive the signal light. Traditionally, SBS is avoided, but it is a phase-conjugated light and shifts down relative to the source light, so it can be used as a reference light in the laser interference structure to achieve up-conversion heterodyne velocimetry. Compared with general homodyne velocimetry (DPS), SBS-PDV naturally upconverts and has more interference fringes and higher resolution at low-speed measurement. In the gas multiple reflection impact compression experiment, the velocity measurement results of SBS-PDV and dual-laser heterodyne Velocimetry (DLHV) are basically consistent, and the accuracy is better than 0.8%. Due to its coaxial heterodyne optical path, this kind of photonic Doppler velocimetry is suitable for low-velocity and long-distance practical applications in the field of shock wave physics.

ANALYSIS OF NULL RESULTS OF HAMMAR EXPERIMENT BY CLASSICAL MECHANICS WITHOUT SPECIAL THEORY OF RELATIVITY

In optics interferometers are used for precision measurements. In interferometry two waves of light are superimposed to generate interference fringes. The interference pattern is observed and analyzed to measure physical process. Gustaf Wilhelm Hammar conducted an experiment in the year 1935 to test aether drag hypothesis. The null results of this experiment were interpreted in consistent with special theory of relativity. Hammar used common path interferometer and observed the changes in interference fringes due to motion of earth. The present work describes that when there is no aether and no medium drags the light in its direction of motion than what will be the behaviour of light.The analysis has been made according to classical mechanics keeping in view Huygen’s principle by tracking the pathways of both the rays of light.It is established that speed of light is independent of velocity of any object,apparatus or any observer and there is no effect of motion of earth.The null results of Hoek’s experiment and Hammar experiment are in consistent with classical mechanics.

High-Precision Atom Interferometer-Based Dynamic Gravimeter Measurement by Eliminating the Cross-Coupling Effect

A dynamic gravimeter with an atomic interferometer (AI) can perform absolute gravity measurements with high precision. AI-based dynamic gravity measurement is a type of joint measurement that uses an AI sensor and a classical accelerometer. The coupling of the two sensors may degrade the measurement precision. In this study, we analyzed the cross-coupling effect and introduced a recovery vector to suppress this effect. We improved the phase noise of the interference fringe by a factor of 1.9 by performing marine gravity measurements using an AI-based gravimeter and optimizing the recovery vector. Marine gravity measurements were performed, and high gravity measurement precision was achieved. The external and inner coincidence accuracies of the gravity measurement were ±0.42 mGal and ±0.46 mGal after optimizing the cross-coupling effect, which was improved by factors of 4.18 and 4.21 compared to the cases without optimization.

Real-time tracking of the adsorption of bovine serum albumin on lipid layer and its effect on lipolysis by optical interferometry

The model proteins bovine serum albumin (BSA) and lipid layer were used to study the effect of proteins on lipolysis. A lipid layer with an interference effect was constructed by loading the triolein into the silica colloidal crystal (SCC) film. The ordered porous layer interferometry (OPLI) system was used to track the changes in lipid layer mass caused by lipase hydrolysis to achieve real-time lipolysis detection. The real-time tracking of the adsorption of BSA on the lipid layer by converting the migration of interference fringes caused by the change of the lipid layer into the optical thickness change (ΔOT). The effect of BSA on the early and late stages of lipolysis was studied, and lipases containing 5 mg/mL BSA degraded the lipid layer 3.4 times faster than lipases containing 0.1 mg/mL BSA in the later stages. This study deepens the understanding of protein-lipid interactions in complex digestive environments.