Optical Principles Research Articles

Dynamic Optical Encryption Fueled via Tunable Mechanical Composite Micrograting Systems.

Optical grating devices based on micro/nanostructured functional surfaces are widely employed to precisely manipulate light propagation, which is significant for information technologies, optical data storage, and light sensors. However, the parameters of rigid periodic structures are difficult to tune after manufacturing, which seriously limits their capacity for in situ light manipulation. Here, a novel anti-eavesdropping, anti-damage, and anti-tamper dynamic optical encryption strategy are reported via tunable mechanical composite wrinkle micrograting encryption systems (MCWGES). By mechanically composing multiple in-situ tunable ordered wrinkle gratings, the dynamic keys with large space capacity are generated to obtain encrypted diffraction patterns, which can provide a higher level of security for the encrypted systems. Furthermore, a multiple grating cone diffraction model is proposed to reveal the dynamic optical encryption principle of MCWGES. Optical encryption communication using dynamic keys has the effect of preventing eavesdropping, damage, and tampering. This dynamic encryption method based on optical manipulation of wrinkle grating demonstrates the potential applications of micro/nanostructured functional surfaces in the field of information security.

The Design, Modeling and Experimental Investigation of a Micro-G Microoptoelectromechanical Accelerometer with an Optical Tunneling Measuring Transducer

This treatise studies a microoptoelectromechanical accelerometer (MOEMA) with an optical measuring transducer built according to the optical tunneling principle (evanescent coupling). The work discusses the design of the accelerometer’s microelectromechanical sensing element (MSE) and states the requirements for the design to achieve a sensitivity threshold of 1 µg m/s2 at a calculated eigenvalue of the MSE. The studies cover the selection of the dimensions, mass, eigenfrequency and corresponding stiffness of the spring suspension, gravity-induced cross-displacements. The authors propose and experimentally test an optical transducer positioning system represented by a capacitive actuator. This approach allows avoiding the restrictions in the fabrication of the transducer conditioned by the extremely high aspect ratio of deep silicon etching (more than 100). The designed MOEMA is tested on three manufactured prototypes. The experiments show that the sensitivity threshold of the accelerometers is 2 µg. For the dynamic range from minus 0.01 g to plus 0.01 g, the average nonlinearity of the accelerometers’ characteristics ranges from 0.7% to 1.62%. For the maximum dynamic range from minus 0.015 g to plus 0.05 g, the nonlinearity ranges from 2.34% to 2.9%, having the maximum deviation at the edges of the regions. The power gain of the three prototypes of accelerometers varies from 12.321 mW/g to 26.472 mW/g. The results provide broad prospects for the application of the proposed solutions in integrated inertial devices.

Exploring color concepts in physics education: Addressing common preconceptions among teachers‐in‐training

AbstractIn the field of physics education, the identification of students' preconceptions—especially regarding light and color—has been pivotal, as these foundational ideas often persist through higher education. Within teacher education, this is particularly crucial, as these early conceptions can deeply influence how future educators understand and teach these concepts, highlighting the need for an approach that weaves these initial understandings into a coherent scientific framework. Instructing students on color concepts reveals that many grapple with the fundamental optical principles. These initial understandings are integral to designing educational sequences that facilitate conceptual evolution, allowing for a deeper grasp of scientific ideas. This study aimed to examine and interpret the initial conceptions that aspiring primary and secondary educators hold about color and its optical fundamentals, while also developing and applying virtual teaching resources to promote a conceptual change about these foundational concepts. A quasi‐experimental approach was employed, comprising control and experimental groups, and utilizing both qualitative and quantitative methods for a comprehensive analysis. Engaging 409 trainee teachers through non‐probabilistic sampling, the study stratified participants by degree program. These groupings facilitated a comparative evaluation of the pedagogical efficacy of the educational resources developed. The study utilized an online assessment comprising single‐answer multiple‐choice questions, grounded in prior research, which was psychometrically validated. Educational tools were then developed and implemented to foster a deeper understanding of color concepts among prospective teachers. Results analysis highlighted the existence of preconceptions about color among participants from diverse educational backgrounds. The interventions employed were effective in catalyzing a shift in conceptual understanding and in elevating the knowledge levels of the trainee teachers.

Casting shadows on the eye to reveal the inverted retinal image

ABSTRACT We introduce and discuss an entoptic effect that helps to demonstrate that images on the retina are optically inverted and reversed. This simple consequence of geometric optics can seem somewhat abstract to students, but this effect is vivid, surprising, and links optical principles to students’ own subjective experience of seeing. Moreover, it requires nothing more than a bright light source, an opaque card that can be punctured to create a pinhole, and a pencil, pen, or other instrument with a fine tip. The phenomenon is not new, but we present it here in the hopes that it becomes more widely known and used in perception science instruction. We describe the necessary setup to achieve the effect, key observations, and briefly outline an explanation. We also contextualize the effect in historical discussion and observations of the inverted retinal image, including discussion of the pedagogical use of pinhole cameras in vision science instruction. Overall, this effect provides a simple yet dramatic demonstration of basic principles of image formation in the human eye.

Measurement of Fugitive Particulate Matter Emission: Current State and Trends

Fugitive particulate matter (FPM) refers to a mixture of solid particles and liquid droplets that are released into the air without passing through confined flow equipment. These emissions of FPM can originate from natural processes and anthropogenic activities. FPM emissions are an important source of PM2.5. Precisely measuring the size, concentration, and other properties of such particulate matter is crucial for effectively controlling emission sources and improving air quality. However, compared with particulate matter emission from stationary sources, it is difficult to monitor the FPM effectively owing to its dispersive and irregular emissions. Traditional measuring methods for FPM are based on sampling, which is a point monitoring approach and can be time-consuming. In recent years, several new techniques based on optical principles, image-based processes and low-cost sensors have been developed and applied for FPM measurement, with the advantages of spatial and time resolutions. The current state and future development of FPM measurements are reviewed in this paper.

Imaging polarimeter with high-accuracy measuring principles in crystal optics

Imaging polarimeter with high-accuracy measuring principles in crystal optics

Beam shaping elements for single photon sources based on 3D printed micro-optics

Multiple researchers have explored the use of 3D printed micro-optical components as interfaces to quantum point emitters by considering different designs and configurations. Typically, these designs involve parametric structures optimized in combination with idealized point source models following the principles of imaging optics. In this work, we propose a different approach based on the use of well-known numerical routines developed in the field of illumination optics. We compare the obtained design to reference parametric 3D printed based interfaces, which have been used in the context of 3D printed micro-optical interfaces to single photon sources.

Research on multi-sensor data fusion technology for underwater robots for deep-sea exploration

Abstract The ocean area occupies a large part of the earth’s area, how to use underwater robots to carry out deep-sea exploration tasks has become an urgent problem in the field of marine resources. In this paper, we design a small AUV underwater robot from five aspects: power supply, control motherboard, power, communication, and sensor. Due to the complexity of the underwater environment during deep-sea exploration, the sensors of the underwater robot need to be calibrated to facilitate data collection and acquisition. To acquire and process underwater image data, the robot uses optical and acoustic imaging principles. The bitmap algorithm is employed to construct a multi-sensor fusion model for depth detection, which is then analyzed for application. The underwater robot is basically able to reach the specified position quickly and smoothly according to the set motion, and its underwater robot infiltrating the bitmap algorithm (x-axis time of 89s, y-axis time of 98s, and z-axis time of 99s) is obviously faster than that of the traditional SLAM algorithm in terms of convergence speed. The underwater robot navigates approximately 400 m in advance of the deep-sea probe’s localization, which allows for fast and stable error convergence. This study meets the covertness requirements of underwater robots when performing detection tasks, and can achieve independent and autonomous navigation of underwater robots, which has a good application prospect.

Simulation analysis and collaborative optimization of key components of the precision detection platform for high precision encoder

To realize the error detection of the high-precision photoelectric encoder, the optical small-angle precision measurement principle of the photoelectric autocollimator and single-sided mirror, and the 360° full circle measurement principle of angle inversion of the compound biaxis turntable are used to establish the precision detection platform of the encoder. The error model of the biaxial structure in the photoelectric coding error detection platform is established by introducing the error sources of the biaxial structure, such as the coaxiality error, angular position error, and installation error. At the same time, the biaxis structure and error models are used to optimize the compound biaxis structure system. By analyzing the natural frequency and vibration characteristics of the structure, the rationality and reliability of the compound biaxis system of the high-precision encoder precision detection platform are verified.

Plasmon-enhanced second harmonic generation of metal nanostructures.

As the most common nonlinear optical process, second harmonic generation (SHG) has important application value in the field of nanophotonics. With the rapid development of metal nanomaterial processing and chemical preparation technology, various structures based on metal nanoparticles have been used to achieve the enhancement and modulation of SHG. In the field of nonlinear optics, plasmonic metal nanostructures have become potential candidates for nonlinear optoelectronic devices because of their highly adjustable physical characteristics. In this article, first, the basic optical principles of SHG and the source of surface symmetry breaking in metal nanoparticles are briefly introduced. Next, the related reports on SHG in metal nanostructures are reviewed from three aspects: the enhancement of SHG efficiency by double resonance structures, the SHG effect based on magnetic resonance and the harmonic energy transfer. Then, the applications of SHG in the sensing, imaging and in situ monitoring of metal nanostructures are summarized. Future opportunities for SHG in composite systems composed of metal nanostructures and two-dimensional materials are also proposed.

Research on the application of information technology modeling based concrete reinforcement construction for bridge projects

Abstract This paper discusses the application of concrete in bridge and house reinforcement, especially for detecting tiny defects during construction. Taking the optical principle of shear device and the principle of scattering interferometry as the theoretical basis, the article proposes a nondestructive testing technique applicable to concrete construction in bridge engineering. This technique can effectively detect the tiny defects in the structure by combining the time phase shift interferometry. The research and analysis show that the digital shear scattering interferometric detection system proposed in this paper performs well in defect detection, and its calculated defect values are highly similar to the actual data with an error of less than 6%. The system can also present different responses in time according to the different lengths or depths of the defects. Further applications showed that the vibration resistance of the bridges was significantly improved after the concrete reinforcement construction using the defects detected by the system, and the self-oscillation cycles were reduced by 8.1% and 11.8%, respectively. Overall, the study provides an efficient technical method for detecting and treating defects in concrete reinforcement works.

CONCENTRATION OF SUSPENDED SOLIDS BY SPECTROPHOTOMETRY

The use of sensors with optical principles designed to estimate sediment transport, and mainly the concentration of suspended solids (CSS) constitutes a robust technique that is currently consolidated and well disseminated in the scientific community, thus configuring an important tool in research, management and control of river basins. The present study, carried out in a water body located near the mouth of the Coxim River - (Coxim, MS), consisted of comparing Nephelometric Techniques and the integrated area of ​​absorbance at wavelengths in the spectrum from 400 to 600 mm (A400-600) and these are measured using a UV/VIS spectrophotometer for indirect determination of CSS. This water body showed characteristics of high sediment input; and for the purpose of possible relationships between the parameters and the characterization of suspended sediments transported by the river, the granulometry (Medium Sand, Fine Sand, Silt and Clay) of the processed samples was determined. The interactions between the parameters to indirectly determine CSS showed the following correlations: (p<0.001); Nephelometric with (R=0.942) and A400-600 (R=0.959); and the particle size fractions, in turn, indicated: (%) of Silt (52.6 ± 17.4), in addition to values ​​close to the distribution of Clay (15.3 ± 6.73), Fine Sand (15.6 ± 10.83) and Medium Sand (16.7 ± 11.84). In this context, according to the results of the residues and correlations, it was observed that A400-600 behaved in a more allusive way compared to the Nephelometric technique in drought and flood events, thus estimating the Detection Limit for CSS (26 .47 mg.L-1 and 44.67 mg.L-1) respectively.

Recent Development of Lens Array Fabrication: A Review

The lens array is a multi-functional optical element, which can modulate the incident light such as diffusion, beam shaping, light splitting, and optical focusing, thereby achieving large viewing angle, low aberration, small distortion, high temporal resolution, and infinite depth of field. Meanwhile, it has important application potential in the form, intelligence and integration of op-to electronic devices and optical systems. In this paper, the optical principle and development history of lens arrays are introduced, and the lens array fabrication technologies such as ink jet printing, laser direct writing, screen printing, photo lithography, photo polymerization, hot melt reflow and chemical vapor deposition are reviewed. The application progress of lens arrays in imaging sensing, illumination light source, display and photovoltaic fields is presented. And this paper prospected the development direction of lens arrays, and discussed the development trends and future challenges of new directions such as curved lenses, superimposed compound eye systems, and the combination of lenses and new op-to electronic materials.

Anti-Environmental Aging Passive Daytime Radiative Cooling.

Passive daytime radiative cooling technology presents a sustainable solution for combating global warming and accompanying extreme weather, with great potential for diverse applications. The key characteristics of this cooling technology are the ability to reflect most sunlight and radiate heat through the atmospheric transparency window. However, the required high solar reflectance is easily affected by environmental aging, rendering the cooling ineffective. In recent years, significant advancements have been made in understanding the failure mechanisms, design strategies, and manufacturing technologies of daytime radiative cooling. Herein, a critical review on anti-environmental aging passive daytime radiative cooling with the goal of advancing their commercial applications is presented. It is first introduced the optical mechanisms and optimization principles of radiative cooling, which serve as a basis for further endowing environmental durability. Then the environmental aging conditions of passive daytime radiative cooling, mainly focusing on UV exposure, thermal aging, surface contamination and chemical corrosion are discussed. Furthermore, the developments of anti-environmental aging passive daytime radiative cooling materials, including design strategies, fabrication techniques, structures, and performances, are reviewed and classified for the first time. Last but not the least, the remaining open challenges and the insights are presented for the further promotion of the commercialization progress.

Novel contactless torque sensor based on optical coherence

This work proposes a novel contactless sensor to measure the micro torque of a rotating shaft based on the optical coherence displacement measurement (OCDM) principle. The experimental system features a simple mechanical testing system to measure the torque, a calibration device to establish the measurement baseline, and a polyetheretherketone (PEEK) shaft to improve the theoretical resolution of the system up to 0.003 Nm. The torque measurement results indicate that this sensor achieved a maximum nonlinearity error of 0.0484 %, maximum repeatability error of 0.2771 %, and maximum hysteresis error of 0.2252 %. This high accuracy of our system stems from the use of high-precision optical principles and the novel physical mapping of the torque (i.e., processing scales on the shaft surface to represent the twist angle by designing a laser engraving system) capable of resisting the negative effects of radial vibrations. Additionally, our torque measurement sensor possesses broader applicability by effectively resisting the impacts of temperature variations and electromagnetic interference. These attributes make it excel other torque sensors presented in the literature in recent years.

Fraunhofer diffraction at the two-dimensional quadratically distorted (QD) grating.

A two-dimensional (2D) mathematical model of quadratically distorted (QD) grating is established with the principles of Fraunhofer diffraction and Fourier optics. A discrete sampling method is applied for finding a numerical solution of the diffraction pattern of QD grating. An optimized working phase term, which determines the balanced energies and high efficiency of multi-plane images, can be obtained by the bisection algorithm. To confirm the analytical approach described above, the results have been compared with those obtained using a classical numerical model based on Fraunhofer diffraction theory and a fast Fourier transform (FFT) algorithm. The results show that our analytical approach allows the precise design of QD grating and improves the optical performance of simultaneous multi-plane imaging system. An optical setup based on our well-designed QD grating has been appended to the camera port of a commercial microscope, and some preliminary microscopy images have been successfully obtained. Further upgrade of our analytical model is in progress to improve the image quality and promote the applications.

Optical Interferometric MEMS Accelerometers

AbstractLaser interferometry is one of the most accurate measurement technologies whose displacement resolution can reach the femtometer (fm) level. With the development of Micro‐Electro‐Mechanical Systems(MEMS) technology, many excellent optical interferometric MEMS sensors have emerged, which play an essential role in intelligent manufacturing, aerospace, and many other fields. Among them, optical interferometric MEMS accelerometers develop rapidly due to their high sensitivity, low noise, and anti‐electromagnetic interference advantages. Lots of research in optical interferometric chip design, micro‐nano fabrication process, signal demodulation algorithm, and range extension technology are performed, and different types of MEMS accelerometers based on the optical interferometric principles are developed, which have been demonstrated and applied in the fields of disaster monitoring, equipment operation and maintenance, and resource exploration. This paper reviews the development status of optical interferometric MEMS accelerometers, mainly focusing on the critical problems and solutions that need to be solved in the development process of optical interferometric accelerometers, and finally introduces the typical application scenarios.

SPR Biosensor Sensor principle and application progress

SPR Biosensor, full name Surface Plasmon Resonance Biosensor, is an instrument used to detect biomolecular interactions. It has the advantages of high sensitivity, high selectivity and real-time to monitor the interaction between substances in real time by optical principle. The working principle of SPR biosensor is based on surface plasmon resonance effect. When there is a certain refractive index difference between the metal surface and the medium, the incident light will be reflected and transmitted. When a biological molecule or chemical molecule binds to a metal surface, it changes the refractive index of the surface, which causes the Angle and intensity of the reflected light to change. By monitoring the changes in reflected light, the binding process and properties of substances can be obtained. SPR biosensors can be widely used in biomedical fields, such as drug screening, disease diagnosis, protein interaction research and so on. Its simple principle, high sensitivity and strong real-time performance make it one of the indispensable tools in modern biological science research. The development direction of SPR biosensor mainly includes improving sensitivity and selectivity, expanding application field, reducing cost and so on. At present, many improved technologies and methods have emerged, such as the introduction of nanomaterials, microfluidic technology, etc., to improve the performance and practicality of sensors. In conclusion, SPR biosensor is an important bioanalytical instrument with broad application prospects and plays an important role in biomedical research and clinical diagnosis.

Pulse oximetry

An oximeter is a piece of medical equipment that is employed for the sole purpose of measuring the amount of oxygen that is present in the blood and can also be used to keep track of one's overall health. The optical principle serves as the primary foundation for the oximeter's detecting method, which allows it to determine the presence of oxygen in the blood. By using a method that is known as absorption, a particular color of light is shone on the blood. Next, spectral analysis is used to measure the absorption rate of oxygen in the blood after being exposed to various wavelengths of light. This allows one to calculate the concentration of oxygen in the blood and, ultimately, the blooding oxygen saturation. Pulse oximetry can be thought of as an example of a non-invasive biosensor because its operating principle is distinct from that of invasive biosensors. The measurement of pulse oximetry, as well as its development trend and the manner in which this gadget interfaces with a smartphone, will be the primary subject of this article.

Geometric error modeling and compensation for high precision composite optical measurement systems

Composite optical measurement systems are widely used in the field of precision measurement due to their combination of inspection with high accuracy, speed, wide range, real-time, and other advantages. Whereas errors are prevalent in measurements, in order to improve detection accuracy, the systems must be compensated for geometric errors in three-dimensional space. Aiming at the complex situation of multi-probes and multi-zooms in the composite optical measurement system, the current error modelling methods are difficult to be directly applied, so this paper establishes a unified three-dimensional volumetric error model based on the theory of multi-body system and combined with the principle of geometric optics, performs the error verification through the direct measurement method, and finally realises the compensation of geometric error in the continuous space of the whole measurement range. Eventually, the accuracy of the proposed error model and the effectiveness of the error compensation method were verified by a laser interferometer and standard objects to be measured, and the integrated geometric error of the system was decreased by 76.55%, which effectively improved the accuracy of the system. The error modelling and compensation method proposed in this paper provides a new idea for the error compensation of the zoom measurement system, and at the same time, it is universal for the measurement systems of different structures and motion forms, which can be widely used in the field of precision measurement.