Optical Review最新文献

Optical resonators are particularly suitable for anaemia state detection due to small sample size, real-time detection and low power consumption. However, the quality factor and sensitivity of resonant cavity sensors are mutually constrained, so the single objective optimization algorithms proposed so far can only achieve a single optimization of sensitivity or quality factor, which limits chip performance. This article presents a multi-objective optimization design of the runway ring resonant cavity sensor based on the BP-NSGA II algorithm, which has achieved good performance improvement. The simultaneous incorporation of quality factor and sensitivity provides access to key structural design parameters to overcome the limitations of sensitivity and quality factor constraints on each other, thereby improving sensor performance. The results show that the optimized structure has a sensitivity of 439 nm/RIU, a quality factor of 938, a relative error of 1.37% and 3.9% for the sensitivity and quality factor, respectively, a linearity of 0.00004636% for the sensitivity, and a training time of 3 min. The method has the advantages of small errors and short learning time. A new optimization method is provided for the design of the resonant cavity of a runway ring.

The optical force exerted on a Rayleigh dielectric spherical particle by a photonic jet is investigated in the framework of the Rayleigh approximation. The photonic jet is generated by a plane wave illuminating a Generalized Luneburg Lens (GLLs). The electric field of the photonic jet is calculated using Discrete Dipole Approximation (DDA). The effects of wavelength of incident plane wave, focal length and radius of the GLLs on optical force are analyzed. Numerical results show that the stability of the captured particles can be controlled by changing the incident wavelength, focal length and radius of the GLLs.

Visibility high-precision measurement has a wide range of applications in the field of aviation and navigation. This paper proposes and designs a visibility measuring system based on a multi-reflection cell. In terms of the definition of the meteorological optical range (MOR), this system calculates the distance at which the beam is attenuated to 5% by means of multiple reflections with a long propagation distance, so as to obtain accurate atmospheric visibility. Different from the short-distance ring-down cavity with a length of 0.5 m, the length of the multi-reflection cell of this system can reach more than 10 m. Compared with the traditional transmissive method, the calculation results are more in line with the real situation of the atmospheric environment because the atmospheric non-uniformity and inversion parameters are considered. Experiments show that this method has better robustness and can stably measure atmospheric visibility under the condition of limited equipment space with an error of 5%.

In this paper, we propose a method to increase vection strength through video image processing in the periphery, rather than the center, of the visual field. Specifically, we propose two methods. One is an image stretching process in the visual periphery and the other is an alpha-blending process with an expanding circle grating in the periphery of the field. We clarified the relationship between the processing conditions and vection strength and found that stretching in the left–right direction increased vection strength while stretching in the downward direction did not. When adding expanding grating by alpha-blending, vection strength and duration were increased in almost all cases.

Abstract

We are researching a new display device that allows the public to experience augmented reality without wearable devices. In this paper, we implement an image processing system that improves the dynamically changing image quality deterioration, which is a problem unique to optical systems that project images on the real space, and specify the necessary system requirements from the results of verification of the effect. We quantify the characteristics of blur for each of the three primary colors defined as digital image data, and implement image processing that applies filter correction to the input image data during aerial imaging. Since the effect on image quality depends on what kind of imaging optical path is formed, we designed the device structure assuming that it will be applied to signage products, and built an experimental environment that can analyze the aerial image that the user actually sees. The image subjected to the correction process follows an optical path that forms an image in the air, and the user visually recognizes the image with emphasized edges. We compared the results of the actual aerial image and the simulation results, and clarified the system requirements for realizing an image processing system with higher correction accuracy.

We revealed the optimal feedback parameters of visual, auditory, and tactile modalities in the operation of aerial display and determined that aerial display could be further improved for use of as a contactless human interface by multimodal feedback combining these parameters. We proposed applying a vibration motor to the sole of the foot instead of fingertips to provide vibration as tactile feedback to operate the aerial display. Sensory evaluation tests were carried out to evaluate the optimal feedback parameters for operating the aerial display in three senses: visual (image change); auditory (touch tone); and tactile (vibration), and to evaluate the effect on the operation with a combination of these parameters. We analyzed the variance of the experimental data using Scheffé’s method for obtaining significance levels of paired comparisons. We found that the combination of two or three modalities rather than only a single modality makes the aerial display easy to operate.

Abstract

In order to study the damage behaviors of optical mirrors induced by film defects (as film bumps, film pits and film contaminants) in high-power CW laser, a simulation study was carried out, which considered temperature, thermal stress and thermal deformation in results. The results show that the bumps of the film will primarily absorb laser energy, and its temperature, thermal stress and thermal deformation will become extremely high, which is easy to damage the film; similarly, the film pits will also absorb laser energy for its temperature rise, and the pits will expand to the inwards. The larger the size of the pits, the larger the expansion of melting range will be, and eventually damage the film layer; after absorbing the laser energy, the temperature of the film contaminants is very high (for film contaminants size of 150 μm, its maximum temperature reaching 900 K), even exceeding the damage temperature (523 K) that the film can withstand, and finally causing the film to be ablated.

Self-referential holographic data storage (SR-HDS), which has been proposed as a novel implementation method for holographic data storage (HDS), enables holographic recording without a reference beam. In addition to the signal pattern (SP) to be recorded, an additional pattern (AP) that affects the reconstruction quality is used in SR-HDS. One of the methods for obtaining a designed AP that contributes to high-quality reconstruction involves utilizing local search algorithms, such as the hill climbing (HC) method. However, designing an AP using this method typically requires a significant amount of time. In this study, we proposed a new AP-designing method that uses a deep neural network. By training a network with pairs of SP and designed AP based on a local search algorithm, a designed AP that improves the reconstruction quality of an arbitrary SP can be instantly obtained. APs designed using the deep learning-based method improved the reconstruction quality of SPs to the same level as those designed using the method based on local search algorithm, whereas the time required to obtain one designed AP was reduced by three or four orders of magnitude.

Division of time polarimeter (DoTP) is one of the popular imaging instruments in several applications because of its simple configuration and accurate performance. However, calibration of the optical axis of the used polarizer is also the premise of an accurate polarimeter. In this paper, a novel on-line and accurate method is proposed to calibrate the transmission angle of the polarizer using a Wollaston prism. The Wollaston prism splits the incident light into two light beams with orthogonal polarization directions, which are vertical and parallel with the beams plane, respectively. Then these two beams pass through the candidate polarizer. The detected light intensity can be adjusted by rotating the polarizer, whose position is marked by a digital encoder. The angle of optical axis of the polarizer relative to the line of points of two light beams can be solved by a series of light intensities. Finally, the optical axis of the polarizer is calibrated on-line, and the state of polarization of incident light can be measured accurately. Numerical simulation and experiments have validated the feasibility of the proposed on-line calibration method. The experimental results show that the calibration accuracy is about 0.0106° with a maximum polarization measurement error of 3.7 × 10^–4. In general, the proposed calibration method is very fast, on-line, accurate, and would be a good reference for polarization imaging and polarization calibration.