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

To increase the recording density of optical discs, analog recording techniques such as the use of orthogonal frequency division multiplexing (OFDM) method has been investigated. In OFDM method, the recording signal is separated into several sub frequency bands. So the readout channel becomes tolerant of the deterioration by disturbances such as defocus and disc skew in optical disc systems. Faster

The application of a burst imaging method to digital holography (DH) with multiple image capturing is firstly demonstrated. Nobody has discussed this approach explicitly, although the burst imaging method is not so uncommon. The burst imaging method intermittently captures several images with a high repetition rate followed by a relatively long rest time. If the light wave from an object has a much

As an object is passing through a static scattering medium, a speckle is formed. We can reconstruct the image from the speckle, based on the principle of optical memory effect. However, when the object passes through a dynamic scattering medium, such as fog, the reconstructed image quality will be degraded even blurred. In this paper, we want to investigate the reconstructed image as the object passes

Nodes in a body area network (BAN) are miniature wearable or implantable battery-powered wireless sensors which continuously transmit real-time vital physiological data of a patient to remote health-care center while remaining in close proximity to the human body. Therefore, BAN nodes should have the features of high data rates and low transmit powers to protect the human body, environment and bio-medical

When a monochromatic electromagnetic plane-wave arrives at the flat interface between its transparent host (i.e., the incidence medium) and an amplifying (or gainy) second medium, the incident beam splits into a reflected wave and a transmitted wave. In general, there is a sign ambiguity in connection with the \(k\)-vector of the transmitted beam, which requires at the outset that one decide whether

The bidirectional reflectance distribution function (BRDF) that describes an angle-resolved distribution of surface reflectance is available for characterizing surface properties of a material. A one-shot BRDF imaging system can capture an in-plane color mapping of light direction extracted from a surface BRDF distribution. A surface roughness identification method is then proposed here using the imaging

The correlation between electrical properties and surface plasmon resonance (SPR) wavelength was discussed using ITO grating coupler. ITO films were prepared on SiO\(_{2}\)/Si substrate by RF sputtering with thermal annealing, and the grating was directly fabricated on the sample surface by focused ion beam. Electron density and mobility were evaluated by fitting optical reflection spectra according

We developed a modulation code using a complex amplitude and established a method to demodulate the code based on a convolutional neural network (CNN) for holographic data storage. The developed 20:9 modulation code consists of nine symbols, each of which contains 4 bits of data representing the symbol position on which the complex amplitude is superimposed and 16 bits of data representing the actual

A computer-generated moiré profilometry based on flat image demodulation is proposed. A sinusoidal fringe pattern and its background light are modulated by two-frequency carrier fringes, respectively, to combine a composite grating. While this composite grating is projected onto the measured object, the composite deformed pattern can be captured by CCD camera. So the sinusoidal deformed pattern and

We propose colors light detection and ranging (LiDAR) using visible laser diodes (LD) of red, green, and blue (RGB) colors to identify colors as well as obtain position information of surrounding objects. To verify the principle, we performed round-trip time-of-flight (TOF) measurements by irradiating a target of different colors with pulsed light from a LD of RGB colors. It is clarified that accurate

A plasmonic planar lens operating at terahertz (THz) region based on InSb micro-slit array with varying dielectric slit width is designed and numerically investigated. Dielectric slits provide desired phase retardations of beam manipulating with varying phase propagation constant. Taking advantage of the permittivity thermo-tunable property of InSb, the focal spot of this lens can be actively controlled

A measurement system based on the Scheimpflug principle is designed in this paper to solve the problem of difficulty in clear imaging due to excessively small depth of field in line-structured light close-range photogrammetry. A conversion model from the image coordinate system to the measured object coordinate system is established through the spatial projection relationship. The calibration method

The response of light in a nonlinear dispersive medium is governed by the nonlinear Schrödinger equation (NLSE). In general, for higher order group velocity dispersion (GVD) with frequency-dependent gain or absorption, NLSE is numerically solved using the split-step Fourier method. Extended NLSEs including the effects of higher order GVD, frequency-dependent gain and frequency-dependent absorption

We have previously presented a blood perfusion parameter by means of the spatial contrast of speckle patterns observed for blood perfusion in skin tissue and a blood vessel. This parameter permits us to visualize a relative blood perfusion distribution from a single speckle pattern. Therefore, it can estimate the blood perfusion with a frame rate of an imaging device employed. This parameter is, however

We propose a layout estimation method for multi-layered ink using a measurement of the line spread function (LSF) and machine learning. The three-dimensional printing market for general consumers focuses on the reproduction of realistic appearance. In particular, for the reproduction of human skin, it is important to control translucency by adopting a multilayer structure. Traditionally, layer design

To reduce the effect of atmospheric turbulence and stabilize the optical link in free-space optical (FSO) communications, we have proposed to use an optical duplicate system (ODS) as a multi-beam generator. In this paper, a transmitter adopting the ODS is designed and constructed for the experiment. Moreover, the experiment is conducted to transmit multi-beam generated by the ODS between two points

Polarization is useful for estimating surface normals. In this paper, polarization is applied to shape estimation. Surface normal estimation from a single image is commonly performed by shape-from-shading. An alternative approach is shape-from-polarization, which usually cannot uniquely determine the surface normal and must be accompanied by additional information. The shading information is a promising

Based on a Nd:LaMgAl11O19 (Nd:LMA) disordered crystal, we have experimentally demonstrated a diode-pumped high-repetition-rate Q-switched laser, which can operate at 1056, 1083 nm, or 1056 and 1083 nm, respectively, using a SF6 prism to adjust the cavity loss. For the three states, the characteristics of the Nd:LMA laser including the average output power, pulse width and frequency repetition rate

Remote visual testing by video cameras is the standard process for inspecting the pressure vessel of nuclear reactors. The inspectors need to find stress corrosion cracking of around several tens of µm wide on a display monitor observed by remote wired cameras in the reactor pressure vessel filled with cooling water. The inside surface of the vessel structure has typically been blasted or grinded during

We demonstrate a single-shot uniaxial 3D profilometry system that illuminates a sample with a structured polarization pattern and measures the reflected full-Stokes polarimetric image. Some non-contact 3D measurements require evaluating samples located in a protected environment. For example, this may be a sample under the lid of an acrylic Petri dish, a sample that has a protective film overlay, or

In this study, a simple hollow core hexagonal structured photonic crystal fiber is offered and analyzed to discern commonly used different type of alcohols in our daily life. The proposed sensor guiding properties are numerically investigated using a full vectorial finite element software-based scheme. To ensure higher accuracy, the properties of alcohols (refractive index and dielectric constant)

In this letter, the high-order harmonic generation (HHG) of wurtzitic and hexagonal boron nitride (h-BN) under ultrafast intense laser field was studied by solving an extended multiband semiconductor Bloch equations (SBEs). The results showed that for both the wurtzitic and hexagonal structures, the cutoff energy of the HHG was extended linearly by increasing the field strength, and the efficiency

Based on the probability density function of the composite channel considering Malaga atmospheric turbulence, pointing error and atmospheric path loss, the asymptotic expressions of channel capacity and outage probability for binary phase shift keying (BPSK) modulation system are derived using Meijer G function. The numerical results show that under the same intensity of turbulence and path loss condition

Orbital angular momentum (OAM) beams have orthogonality between them, which can greatly increase the capacity of a communication system, but an OAM multiplexed communication system will be affected by atmospheric turbulence during transmission, which will cause channel crosstalks. In this paper, we adopt the blind equalization algorithm, which can recover multiple signals with blinding source separation

We have provided two compact designs of on-chip silicon photonic crystal (PhC) AND and XOR logic devices, which can provide multiple logic functions through different input frequencies within one structure. Compared to the former ones, the overall size is short to 10a × 18a (approximately 4 × 8 μm2). The working principle of the structures is lead to the directional leakage of the center cavity and

In this work, the polarized beams tightly focused through a cylindrical refractive-indices discontinuous dielectric interface was numerically investigated. The corresponding focal pattern calculation formula was deduced base on vectoral diffraction integration theory for the first time. The patterns through the cylindrical dielectric interface with different radii were revealed by numerical calculating

We have developed a new high-speed driving circuit of a multi-color LED panel by the use of FPGA for subjective super-resolution display. In the subjective super-resolution display, the coded display image is switched and displayed at high speed. The viewer makes an unconscious correction by fixational eye movement and perceives the resolution higher than the physical number of pixels of the LED panel

The design requirements of the Fourier transform optical system required for synthetic aperture radar(SAR) are analyzed and the specific optical parameters are determined. The design of the Fourier lens adopts a fully symmetrical structure to avoid simultaneous optimization of the forward and reverse directions of the optical path and can complete the correction of the conjugate positional aberrations

A novel structure for photonic frequency-multiplication millimeter-wave (mm-wave) generation with two cascaded dual-parallel Mach–Zehnder modulators (DPMZMs) but no optical filter is demonstrated. By properly adjusting the phase and amplitude of radio frequency (RF) driving signal and the bias points of two DPMZMs, frequency 12-tupled, 18-tupled, or 24-tupled high-spectral-purity mm-wave signals are

We propose a highly doped circular photonic crystal fiber (HDC-PCF) in which solid fiber core is surrounded by four layer circular rings consisting of air holes in the cladding. The condition of flattened dispersion and very low confinement loss has been achieved by introducing air-filled circular tiny defects in the core region. When we designed a defected core HDC-PCF by introducing one, two, three

Using the finite element method, we numerically investigated the transient behavior of molecular orientations of a liquid crystal (LC) lens with a circular electrode beside a hole-patterned electrode and a common flat electrode that has a resistive film. The transient properties of a three-dimensional electric field and the molecular orientations of the LC were simultaneously calculated when voltages

In this paper, we present the evaluation of a predesign of a zoom system based on a variable-focal-power lens by paraxial and aberration analyses only. This zoom system involves less mechanics and has a more compact design than those using a fixed-power lens. We derive corresponding formulas between the focal power of each lens and the magnification of the zoom system, and the bendings of the variable-focal-power

In this paper, we propose a full duplex architecture based on a hybrid link composed of free space optics (FSO) and multimode plastic optical fiber (MMPOF) for short-range wireless access networks. The proposed architecture employs mode group division multiplexing (MGDM) and wavelength reuse techniques to transmit data between central unit (CU) and radio access units (RAUs). An optical frequency comb

Importance of simultaneous measurement of temperature and strain by fiber Bragg grating (FBG) sensors has led to innovation of several renewing techniques. Most of them are based on two FBGs configurations or one non-uniform FBG implementation. Both temperature and strain changes can result in Bragg wavelength shift in reflected spectrum from a uniform FBG. We propose using full width at half maximum

In this paper, we propose a cost-efficient single mode fiber-free space optics (SMF-FSO) based hybrid \(32 \times 2~\text{Gbps}\) wavelength division multiplexed passive optical network (WDM-PON) employing optical frequency comb (OFC) source and polarization multiplexing. OFC source is realized at optical line terminal (OLT) by modulating a single continuous wave (CW) laser source with radio frequency

We have realized a novel optical system to form a large aerial image in front of a full-color LED panel that is covered with retro-reflector. The retro-reflector has square apertures through which lights from the LED pixels pass. Our optical system is based on aerial imaging by retro-reflection (AIRR). The aerial image formed with AIRR is visible over a wide viewing angle without using 3D glasses.

In this study, the effects of selectively yellow-cut lenses on contrast sensitivity were investigated in healthy young and middle-aged individuals and elderly patients with cataract. Contrast sensitivity in middle-aged healthy individuals and elderly patients with cataract was higher when measured while the subjects were wearing selectively yellow-cut lens (NeoContrast; Mitsui Chemicals, Inc., Tokyo

Sound evokes sub-nanoscale vibration within the sensory epithelium. The epithelium contains not only immotile cells but also contractile outer hair cells (OHCs) that actively shrink and elongate synchronously with the sound. However, the in vivo motion of OHCs has remained undetermined. The aim of this work is to perform high-resolution and -accuracy vibrometry in live guinea pigs with an SC-introduced

A three-dimensional (3D) shape measurement method based on speckle-embedded fringe patterns (composite fringe patterns) and wrapped phase-to-height lookup table (LUT) is proposed. As an auxiliary signal, speckle is embedded into the phase domain of the projected fringes, and the wrapped phase and deformed speckle modulated by the objects are demodulated by phase-shifting algorithm. With the assistance

The demand for high bandwidth on the Internet is growing drastically, and one of the solutions for tackling this problem is using optical networks. Burst switching is one of the techniques that can be used in optical networks to handle high traffic. Aside from the many advantages that this technique has, it suffers from a big flaw called burst contention. Optical burst switching (OBS) is a switching

A reconfigurable and application-specific tunable microwave photonic filter having finite impulse response is proposed. The filter exploits the differential mode group delays of linearly polarized modes in a multi-mode fiber to achieve single and multiple high-frequency passband response. The filter taps are realized using a single continuous wave laser source and differential delays among modes that

Ultrasonic wave has been widely used in the medical field because of its special physical properties. However, it might cause health risk for the human body if the power is inaccurately measured. As a noncontact measurement method, the acousto-optic method gives a lower uncertainty than the mechanical and contact method. To improve the accuracy of ultrasonic power measurement system based on the acousto-optic

In mode-division multiplexing systems, the transmission quality is restricted by the differential mode delay (DMD). We previously proposed a spatial mode exchange technique using volume holograms (VHET) to reduce the DMD. VHET can be used for the exchange of multiple spatial modes with different transmission speeds using a single device. However, in VHET, incidents of cross-talk (XT) caused by non-target

In this study, the effect of the shift in the refractive index between two dispersive elements on the output phase-conjugated (PC) wave power of waveband-shift-free optical-phase conjugators based on difference-frequency generation (DFG-OPCs) is analyzed. First, a numerical model of the DFG-OPC is built by considering the shift ∆n in the refractive index. The derived formula shows that the output PC

A low-noise and fast optical encryption method for three-dimensional (3-D) information using the double-phase method is proposed. First, the 3-D information is encoded into a phase-only hologram (POH) by the angular-spectrum diffraction and the double-phase method. Second, the chaotic random phase mask (CRPM) is generated by the hybrid logical map and the iterative chaotic map with infinite collapses

Terahertz (THz) waves are a promising candidate for detection, imaging, and advanced communications with ultrafast transmission speed. To develop THz technologies, miniaturized devices for controlling THz waves are essential. In this study, a high-performance vanadium dioxide (VO2)-based switchable band-pass metamaterial integrated with a silicon substrate for THz waves is designed and fabricated.

We studied the mechanism causing the fluttering-heart illusion in which the motion of an inner figure appears unsynchronized compared with that of the outer figure surrounding it although the motion of both figures is objectively synchronized in reality. Experiment 1 examined the effect of edges’ luminance contrasts. The illusion was measured under conditions where the luminance contrasts of the outer

Speckle contrast of single, dual, and triple emitter broad area laser diodes (BA-LDs) with a wavelength of 638 nm was experimentally investigated. Speckle noise was relatively small near the threshold current probably due to the longitudinal mode competition. Higher output power led to smaller speckle noise owing to the spectrum widening. A wide stripe presented an advantage in terms of speckle reduction

A novel spectroscopic optical sensor is presented for cancerous cell detection in various parts of the human body (i.e., cervix, adrenal gland, breast, skin, and blood). An optimized structure based on compact cladding is successfully designed with enhanced sensitivity and very low confinement loss. The parameters like effective area (Aeff), V-parameter (Veff), spot size (Weff), numerical aperture

Histogram equalization (HE)-based technology has been widely applied in infrared image contrast enhancement due to its effectiveness and simple implementation. However, HE and its variations considered the accumulation of pixels in different gray values, thus ordinarily result in artifact effects, over-enhancement and noise amplification, especially in the uniformity region. In this paper, we redefine

Phase-shifting fringe analysis using wavelength scanning has been broadly applied to the interferometric profiling of the thickness variation of glass plates. However, the nonlinear phase shifting can cause bias error during wavelength scanning. In this study, the bias error in the calculated phase was formulated by Taylor series expansion. Using the formulation, a novel 15-sample algorithm of a partially

In this paper, the expression for the SNR has been developed through the imaging model. It is concluded that the image SNR decreases with the increase of the number of light-emitting points of the target under the same hardware conditions and experimental parameters. Using uniform bright squares of different sizes as the target, the SNR of the reconstructed image is calculated. Simulation and prototype

Photometric stereo allows us to estimate the surface normal of an object based on its shading. In uncalibrated photometric stereo, the light source direction is unknown; thus, both the light source direction and surface normal should be estimated, which establishes an ill-posed problem with ambiguity in its solution. Consequently, assumptions should be made to uniquely determine the solution; however