The key to measurement by electronic speckle pattern interferometry (ESPI) is to obtain accurate phase information from the ESPI fringe patterns. We propose a fast batch skeleton extraction method for ESPI fringe patterns using the pix2pix conditional generative adversarial network (pix2pix cGAN). The network is trained by ESPI fringe patterns and complete skeleton images, and the trained network can

Images captured in backlit conditions (i.e., backlit images) often have a vast difference in lightness between bright and dark areas. In such a dark area in an image, the visibility becomes extremely low, making it indistinct to recognize the subject. Sufficient image quality cannot be obtained by simply applying a general image enhancement method to such a backlit image. Many methods specializing

Multi-spectral filter array composed of a wavy alternating dielectric multilayer was integrated on a CMOS image sensor of the Raspberry Pi HQ Camera. The filter array consists of 16-channel elementary filters exhibiting pseudo-random transmission characteristics. Each filter covers \(20\times 20\) CMOS pixels. The incoming spectrum is encoded as a set of 16 grayscale intensities and passed to principal

The photonic band structures of waves in configuration-periodic equilateral polygonal networks (EPNs) are studied in the paper. The results indicate that comb-like optical transmission spectrum can be realized by EPNs.The number, width, and range of continuous equidistant frequency bands can be controlled conveniently by adjusting the waveguide length and the unit cell numbers of upper arm. Those comb-like

A three-core photonic crystal fiber (PCF) sensor based on surface plasmon resonance (SPR) has been designed with silver film coated on the inner wall of a microfluidic detection channel with three V-grooves. The coupling characteristics and sensing properties of the proposed sensor are analyzed numerically using the full vector finite element method (FEM). The loss spectra and the sensing performance

This paper evaluates the spatial distortion of aerial image and proposes a novel optical design to utilize the distortion as visual expression. Our optical system is based on aerial imaging by retro-reflection (AIRR). Using acrylic plate as beam splitter, a clear aerial image can be obtained at low cost. However, when upsizing the device, there is a problem that aerial image was distorted because the

Laser-driven phosphor conversion (PC)-type white light sources are receiving a great deal of attention in next-generation high-intensity lighting and display technologies. Laser lighting is attracting attention for its functions, such as energy saving and light distribution control. However, the PC-type white light source has problems with color control and thermal quenching. Thus, monochromatic light

For improving the performance of vibration discrimination in terms of dual Mach–Zehnder interferometric (DMZI) perimeter system, we proposed a novel method based upon the multifractal theory, serial feature fusion as well as improved probabilistic neural network (PNN). By the multifractal theory, the features of original signal are extracted in the form of multifractal spectrum parameters, thereby

AIRR (Aerial imaging by retro-reflection) can form a large aerial image in mid-air for digital signage. Resolution of the aerial image formed with AIRR is determined mainly by the retro-reflector, which is one of its components. However, increasing the resolution of aerial images by increasing the density of retro-reflective elements poses physical limitations and cost increases. The purpose of this

The Preisendorfer and Mobley Monte Carlo model is a classical photon-rough sea surface interaction model that is used to study the reflectance and transmittance properties of the wind-driven sea surface. In this paper, we develop a computational framework and the implementation for parallel processing of this model by using Message Passing Interface. We then analyze the correspondence between serial

This paper proposes a novel steganography method to show an aerial image that is formed with aerial imaging by retro-reflection by use of dual transparent balls made of acrylic resin. Our optical system forms a floating image screen in front of an acrylic ball that is placed on a beam splitter. We have confirmed our proposed optical system by performing optical ray-tracing simulations and experiments

A microfluidic device was developed for coherent diffraction imaging using an X-ray free-electron laser (XFEL-CDI). Liquid samples, which are separately packed in reservoirs of the device, are mixed in a flow channel after an XFEL irradiation as a trigger. An XFEL-CDI experiment was conducted and images of gold nanoparticles in solution were obtained with a resolution of several nanometers from single-shot

An ultra-compact plasmonic unidirectional wavelength multiplexer/demultiplexer based on slot cavities is proposed and numerically simulated. The structure consists of slot cavities which are etched on either sides of a metal–insulator–metal (MIM) bus waveguide. The cavities capture surface plasmon polariton (SPP) waves at their resonant wavelengths and unidirectionally couples them to the drop waveguide

An extreme enhancement of the polar Kerr magneto-optical (MO) effect was numerically demonstrated using surface plasmon polaritons (SPPs) at the SiO2/Ni interface combined with the Ni-subwavelength grating (SWG). Utilizing the ω–k dispersion relation for the SPP at the SiO2/Ni interface, the parameters of Ni-SWGs were designed to couple the SPP mode with the incident light. The electromagnetic field

Heat-assisted magnetic recording is a technology to improve recording density for hard disks. The authors’ group has proposed a device, in which a gold nano-antenna as a near-field transducer is attached to a semiconductor ring resonator as an integrated light source. Localized surface plasmon resonance at the tip of nano-antenna excites near-field light to form small recorded marks to increase recording

In this study, an automobile wheel type photonic crystal fiber (PCF) has been designed to investigate the effect of the background material on analyte sensing. The designed PCF has a circular hollow core with eight slot-type air holes in cladding. The analysis is performed in the range of 0.5–1.5 THz, and different background materials are chosen during the simulation, for example, fused silica, BK7

This paper reports the linear and nonlinear optical spectroscopic study of tungsten-doped zinc oxide thin films (ZnO:W) with various dopant concentration grown by spray pyrolysis technique on pre-heated glass substrates at 450 °C. The ZnO:W thin films are polycrystalline with the hexagonal wurtzite structure and have a preferred orientation with the c-axis perpendicular to the substrates. SEM investigation

We developed an amblyopia-training device, which can be used easily and inexpensively under binocular conditions with polarizing films. The device uses two polarizing films: one is attached to the training target (such as monitors and books), while the other is attached to the lens of glasses that cover the healthy eye with the absorption axis rotated 90 degrees. This allows the target to be presented

Color shift behavior at the edges of white-and-black line patterns was measured and analyzed for three raster-scan mobile projectors using the three-primary-color (red, green, blue) laser diodes. The 2D data of the line patterns projected on a standard diffusive reflectance screen were captured by a speckle measurement device for analyzing the effects of both the color speckle noise and the edge color

This paper describes the noise analysis of an electro-optic (EO) sensor system based on experimental and simulation results. We developed a polarization simulator of the EO sensor system using the Jones vector and matrix. The polarization simulator included not only the laser intensity noise but also the laser polarization noise. The polarization noise was converted into an intensity noise due to the

In this study, we established consecutive monitoring methods using UAV in pecan orchards of 64 ha each, in San Simon, Arizona, USA. Activity monitoring, tree height map creation and ground surface temperature analysis of trees by UAV with near infrared (NIR)/TIR camera were conducted for pecan orchards in San Simon, Arizona, USA. Using established continuous monitoring methods, the UAV images of a

Fringe projection profilometry (FPP) is a technique used for obtaining the three-dimensional shape of an object in fields such as reverse engineering, cultural heritage, and computer vision. The FPP measurement accuracy significantly depends on the arrangement of the measurement system, measurement space conditions, equipment setting, and object characteristics. However, experimental verification of

For ultra-compact near-eye display, waveguides provide a small form factor because they are thin shape plate, but projectors are too large due to the imaging sources, which results in bulky near-eye displays. Recent advances in fiber-scanning technology can overcome this limitation. Fiber-scasnning projectors produce an image by vibrating an optical fiber, and they can be small because only thin fibers

In this paper, we report the performance evaluation of praseodymium doped fiber amplifier (PDFA) operating in 1.25–1.35 μm band of wavelengths based on theoretical simulation. The performance of the PDFA is evaluated by considering an optimized length of Pr\(^{3+}\) doped fiber, concentration of Pr\(^{3+}\) ions and pump power. Moreover, the impact of input signal wavelength on gain, amplified spontaneous

To enhance the security in optical image encryption scheme and to safeguard it from the invaders, this paper proposes a new scheme using devil’s toroidal lens masks (DTLMs) and QR decomposition in gyrator transform (GT) domain. The proposed cryptosystem utilizes DTLMs which are the complex phase masks designed using the combination of a phases of devil’s mask (\({\rm DM})\) and toroidal mask \(\left({\rm

The double random phase encoding techniques have received considerable attention from researchers in recent years because of their advantages of parallel and high-speed processing capability. Meanwhile, the security of the cryptosystem is also one of the major concerns. We experimentally showed the ciphertext redundancy vulnerability of the coherent double random phase encryption (DRPE) system. Based

During endoscopic surgery, the operation accuracy can be improved if the endoscope system provides 3D information. In this paper, an adaptor lens is presented for a commercial 2D endoscope to generate stereoscopic images. The function of the adaptor lens is verified in this study, and we prove the adaptor lens can be compatible with an arbitrary rigid 2D endoscope system even if its original imaging

Generalized Kramers–Kronig (K–K) type dispersion relations and sum rules are derived in the static limit for the moments of the degenerate four wave mixing susceptibility. The degenerate nonlinear susceptibility is different from a typical use of the conventional K–K dispersion relations, which assume absence of complex poles of a function in the upper half of complex frequency plane, whereas degenerate

Heat-assisted magnetic recording (HAMR) is a promising technology with high recording density. The authors’ group has proposed a novel device for HAMR, in which a metal nano-antenna as a near-field transducer is attached to a semiconductor ring resonator as a light source. The ring resonator oscillation should be stable to generate steady near-field light with proper energy density to heat the recording

Increasing efficiency and productivity in the field of agriculture is important to provide sufficient food to the world’s increasing population. It is important to monitor crops using image processing in order to realize these increases in efficiency and productivity. In order to monitor crops with high quality and accuracy, high resolution images are needed. In this research, a crop monitoring method

We propose a field of view (FOV) enlargement method using the line symmetric image input in the single layer volumetric holographic waveguide. We build a mathematical model and analyze the virtual image to be seen by the observer considering the interaction volume of the signal light ray within the volumetric hologram waveguide. It is found that the diffracted light intensity is varied with each ray

We present the modeling of a porous core dispersion flatten photonic crystal fiber (PCF) for the fruitful transmission of THz signals. The model comprises only rectangular holes in both core and cladding areas. The model is numerically studied through simulation employing the finite element method (FEM)-based software. Simulation results disclose an insignificant amount of confinement loss (CL) of

A waveguide grating on a transparent substrate can serve as an optical notch filter owing to guided-mode resonance. The filtering wavelength is highly sensitive to an incidence angle. Potential of a two-dimensional grating for an application to three-dimensional angle-fluctuation sensing was investigated. Spectral variations due to the angle fluctuations were theoretically discussed and simulated using