The guest editors summarizes the contributions to Special Section on Laser Damage V.

Understanding of the laser-induced damage threshold and impact of air–vacuum cycling of the optical components in short-pulse laser systems is of fundamental importance. We report the results of a damage-testing campaign that monitored representative pulse compression grating samples that were positioned inside the OMEGA EP grating compressor vacuum chamber during normal operation and routinely damage

We investigate the depth of field (DoF) enhancing capacity of binary annular phase masks embedded in panchromatic imaging systems. We first demonstrate with numerical simulations and real-world imaging experiments that phase masks optimized for monochromatic illumination are somewhat robust to their use under wide spectrum illumination: they provide images that are slightly less sharp but less affected

Planar laser-induced fluorescence (PLIF) techniques have been widely used for flame structure visualization in recent years. Nevertheless, most of the studies were concerned with qualitative analysis of the obtained images and the quantitative analysis were much fewer. This work presents a quantitative feature extraction method to process the ribbon structures that are captured in images and represent

The draft is a measurement of the vertical distance between the waterline and the bottom of the ship hull. The displacement tonnage of a ship then can be calculated by the observed draft. The current draft survey is done by surveyors, which is subject to human errors. We propose to use computer vision with deep learning for draft reading from images. First, mask R-CNN is used to segment the region

We report our in-house R&D efforts of designing and developing key integrated photonic devices and technologies for a chip-scale optical oscillator and/or clock. This would provide precision sources to RF-photonic systems. It could also be the basic building block for a photonic technology to provide positioning, navigation, and timing as well as 5G networks. Recently, optical frequency comb (OFC)-based

Top-Gaussian illumination generation technology has considerable application prospects in photolithography. We propose a detailed design and optimization method for the optical component that generates the top-Gaussian illumination field. This method can generate a field with a specific profile in the scan direction and a rectangular distribution in the nonscan direction. The energy density is reduced

It is insufficiently powerful to compute multi-view images at a high enough frame or data rate to support high quality dynamic three-dimensional displays with the current computer software and hardware. According to the correspondence between lens position and elemental image, a real-time computer-generated content generation method for integral imaging based on cross perspective is presented. A GPU-driven

Plant water stress has been extensively studied using hyperspectral visible- and near-infrared systems. Thermal imaging and the recent availability of widely tunable infrared quantum cascade laser (QCL) allow us to propose an active hyperspectral imaging system operating in the mid-infrared (MIR) band, where the system output consists of a series of narrowband subimages arranged across the reflectance

Most visual trackers focus on short-term tracking. The target is always in the camera field of view or slight occlusion (OCC). Compared with short-term tracking, long-term tracking is a more challenging task. It requires the ability to capture the target in long-term sequences and undergo frequent disappearances and reappearances of target. Therefore, long-term tracking is much closer to a realistic

We propose a technique to generate etendue maintained white light. The proposed technique uses three high-power blue light emitting diodes (LEDs) with identical characteristics to pump green aluminate (GAL) green-yellow phosphor coated on the inner channel of a waveguide. The technique offers two methods of generation of white light. Standalone partial conversion of blue to green and yellow light by

The industrial maturity of ultrashort pulsed lasers has triggered the development of a plethora of material processing strategies. Recently, the combination of these remarkable temporal pulse properties with advanced structured light concepts has led to breakthroughs in the development of laser application methods, which will now gradually reach industrial environments. We review the efficient generation

We propose and demonstrate a photonic approach to generate and transmit a quadrupling-bandwidth dual-chirp microwave waveform with anti-dispersion transmission. Commonly, dual-chirp microwave waveforms are generated by double-sideband modulation, which brings severe chromatic-dispersion-induced power fading (CDIP) over fiber transmission. In this scheme, we perform optical carrier suppression via a

The US Army Night Vision and Electronic Sensors Directorate’s Night Vision Integrated Performance Model (NVIPM) is a robust, comprehensive, and sophisticated model that calculates the performance of an infrared imager in the task of target acquisition. The inputs are specifics about the target, atmosphere, optics, detector, electronics, and display and the outputs are probabilities of target detection

A triple-band metamaterial absorber (MMA), which is ultrathin and polarization-insensitive, is designed and fabricated. The top layer of the MMAs consists of a square-shaped copper film with a cross cut out in the center. The calculation result demonstrates that there are three distinct absorption peaks, which are 5.86, 15.04, and 17.5 GHz, and their corresponding absorption rates are 99.76%, 99.11%

We present experimental methods and results for photo-response non-uniformity correction (PRNUC) in range for a 3D flash LiDAR camera from non-optimal static-scene calibration data. Range walk is also corrected. This method breaks up the camera’s focal plane array (FPA) into 16 × 16 windowed regions of interest that are incrementally captured and stitched together in post-processing across the entire

It has become an imperative reality to find an alternative for the conventional bulk semiconductor optical amplifier (SOA), which suffers from the slow dynamic response, in light of the increased need for higher speeds. In this research, the carrier reservoir SOA (CR-SOA) is employed as a suitable alternative to investigate the all-optical AND logic gate for the first time at an operating speed of

A low-cost laser detection system based on coherence detection has been developed and is able to detect weak, continuous laser sources even against bright background light. The system is composed of a Mach–Zehnder interferometer with one arm modified with a piezo-mounted mirror to modulate the path length. We introduce methods to determine the laser wavelength and to extend the horizontal field of

Phase measuring deflectometry (PMD) is a superior technique to obtain three-dimensional (3D) shape information of specular surfaces because of its advantages of large dynamic range, noncontact operation, full-field measurement, fast acquisition, high precision, and automatic data processing. We review the recent advances on PMD. The basic principle of PMD is introduced following several PMD methods

Analysis of spatial temperature and gas concentration distributions is of great importance for combustion research. Algebraic reconstruction technique (ART) and adaptive algebraic reconstruction technique (AART) based on tunable diode laser absorption spectroscopy are both widely used methods for temperature tomographic imaging in a flame. After being obtained the temperature tomography through iterative

Multiple studies have been carried out to analyze the mutual interaction of a phase-sensitive optical time-domain reflectometer (Φ-OTDR) and parallel digital data traffic. However, interactions with analog transmission, e.g., community antenna television (CATV), have not been addressed. Our study examines and presents the influence of a developed sensing system Φ-OTDR when operated simultaneously on

The optical planar waveguides were fabricated by proton implantation with an energy of 400 keV and a dose of 8 × 1016 ions / cm2 or 400-keV helium-ion implantation with a fluence of 6 × 1016 ions / cm2 in the fluoride lead silicate glass. The morphologies were studied by a Zeiss microscope to estimate the thickness of the waveguides. The annealing effects on the fluoride lead silicate glass waveguides

We propose a 3D Hough transform (3D-HT) algorithm that can overcome the disadvantages of high complexity and large data storage space of the existing 3D-HT-based small target detection algorithms. The proposed algorithm uses two coordinates at different times and coordinate errors to construct a 3D pipeline. Subsequently, it counts the number of points in the 3D pipeline and confirms the presence of

Recent advances in solid-state technologies have enabled the development of light-emitting diodes (LEDs) with favorable features such as long life expectancy, low-power consumption, and reduced heat dissipation. Visible-light communication (VLC) is a short-range wireless access technology that deploys LEDs as wireless transmitters in addition to their primary task of illumination. The major limitation

A concept of noncoaxially propagating discrete data by coding/decoding orbital angular momentum (OAM) of vortex beam through multiple channels is proposed. Four independent channels along different directions (diffraction orders/angles) are established by a series of specially designed holograms. Sixteen vortex beams are used to code each sequence with the length of 4 bits into an OAM mode in each

The Follow-up X-ray Telescope (FXT), a key payload onboard the Einstein Probe sallite (EP), is equipped with a Wolter-I x-ray focusing mirror system. We introduce the principle of such a mirror system and analyze the influence of the mirror gap in the multishell nested mirror of the FXT on the effective area, stray-light ratio, and vignetting. To ensure that no occlusion occurs within adjacent shells

We present an intensity-balanced dual-frequency laser (DFL) based on an Nd: GdVO4 microchip crystal. The intensity balance ratio tuning mechanism of the DFL, which is governed by the heat sink temperature Tc of the laser crystal, is experimentally studied. The experimental results indicate that keeping a balanced intensity condition, when the pumping power of the DFL increases, the heat sink temperature

We investigate hybrid free-space optical (FSO) link in converged baseband and 60-GHz radio-frequency signals under adverse climate conditions. In this approach, optical double-sideband with carrier method is utilized. The adoption of such an FSO system can be contributed to existing fiber-optic architecture. Managing the signal strength by erbium-doped fiber amplifier, deployment of the system serves

The phenomenon of reversed radiation pressure on free electrons in a nanoparticle requires the necessary but insufficient condition that the real part of the particle’s permittivity be negative. It is shown that Rayeigh scattering theory is adequate for modeling the phenomenon by favorable comparison with Mie theory for single particles. A multiparticle Rayleigh scattering approach demonstrates that

The ultrashort, ultrahigh intensity pulse laser has been fully developed in past three decades. Chirped pulse amplification (CPA) system plays an important role in the generation of the ultrashort, ultrahigh intensity pulse laser. Pulse compression gratings (PCGs) are the key element of CPA system and determine the performance and lifetime of the whole system. We introduce the principle of CPA system

The algorithm designing of object localization is one of the key technologies in the research field of high-voltage power transmission line inspection robot. We present an obstacle localization method based on line stereo matching to solve the problems remaining in the current obstacle localization algorithms such as the weak capacity of resisting distraction, the low localization precision, and the

A phase correction method that utilizes fringe color-coding in phase-measuring profilometry is proposed. Original and additional fringes are encoded into the R and B channels, respectively. The R + B channel patterns are projected onto an object, captured using a camera, where the R and B channels are extracted. Then, phase shifts obtained from the R and B channels are utilized for absolute phase calculation

A selectively excited bimodal interferometer was developed for highly sensitive detection of refractive index changes. Numerical simulation revealed that multimode waveguides with tall, narrow cross-sections are suitable for realizing a highly sensitive bimodal (fundamental and lateral first-order modes) interferometer, owing to deeper penetration of the lateral first-order mode through its side surfaces

Additive manufactured Ti6Al4V alloy has excellent comprehensive properties and has broad application prospects in the aerospace, biomedicine, and other fields. However, the fabricated components are too rough to use directly. So, a corresponding postprocess is needed urgently. The conventional finishing process cannot meet the requirements of green and efficient processing because of its time consumption

Digital holography is a well-established technique for tracer particle studies in a flow. Unfortunately, its great depth of focus increases the uncertainty along the Z axis. This drawback becomes very significant when the concentration of seeding particles increases. This is the case in real installations such as wind or water channel flows. In such cases, observing the whole volume, and therefore

A broadband air gap polarization prism design based on Hg2Cl2, Hg2Br2, and Hg2I2 crystals is suggested. Spectral ranges of operation extend from visible light up to 40 μm, and strong birefringence of the materials makes it possible to optimize the crystal cut geometry. Results include a large symmetric field of view up to 20 deg wide within the entire mid- and far-infrared transparency range, as well

In this study, we propose a dual-band wide-range tunable terahertz absorber based on graphene and bulk Dirac semimetal (BDS), which consists of a patterned BDS array, dielectric material, continuous graphene layer, and gold mirror. Simulation results show that the absorption at 3.97 and 7.94 THz achieve almost 100%. By changing the Fermi energy of graphene and BDS, the resonance frequency can be tuned

In vivo optogenetics provide special and powerful capabilities in regulation of neurons, research of neural circuits and even in treatment of brain diseases. However, conventional hardware for such studies tethers the experimental animals to remote light sources, power sources, or other functional modules, which imposes considerable physical constrains on natural behaviors and limits the range of the

The problem of light collection in random lasers (RLs) is addressed. As the radiation emitted by this system is Lambertian due to its spatial incoherence, a device based on an ellipsoidal revolution mirror is designed, developed, and tested in order to optimize the harvesting of the radiation emitted by the RL. The system provides a simple injection procedure of the emitted energy at the entrance of

Ghost imaging (GI) is a technology of nonlocal optical imaging, which is widely used in the field of information encryption. However, there are some inherent shortcomings in the encryption process, such as imperfect security and low imaging precision. To solve these problems, we propose a camouflaged encryption mechanism based on sparse decomposition of principal component orthogonal basis and ghost

Phase unwrapping aims to reconstruct the absolute phase from its values mod 2π, which is a key problem in many non-contact optical metrologies and is still a challenging issue in the presence of noise. We present a robust phase unwrapping method with two steps based on local denoising and the accumulation of residual map (ARM). In the first step, based on the local polynomial approximations and intersection

Fiber-to-chip light coupling using a graded-index (GRIN) fiber collimator is investigated. Our experiments with grating couplers and strip waveguides fabricated in a photonic integrated circuit technology reveal that the peak coupling efficiency of a GRIN fiber collimator is 7.8 dB lower than that of a single-mode fiber. However, the 3-dB alignment tolerance is improved by a factor of about 5.7 giving

The use of capacitive metal meshes consisting of square patches is well established in the design of millimeter-wave optical devices such as filters, half-wave plates, and graded-index lenses. The main property of these meshes, the capacitance, is controlled by the size of the square patch in the mesh’s unit cell up to a limit imposed by the minimum feature size of the manufacturing process. We report

Hyperspectral (HS) imaging retrieves information from data obtained across broadband spectral channels. Information to retrieve is a 3D cube, where two coordinates are spatial and the third one is spectral. This cube is complex-valued with varying amplitude and phase. We consider shearography optical setup, in which two phase-shifted broadband copies of the object projections are interfering at a sensor

An optical-mechanical scanning platform for terahertz imaging is designed and studied based on the single-channel 360-GHz radiometer. The fast scanning of 360-GHz Cassegrain antenna beam is realized through the rotation of a metal mirror with the inclination of 45-deg angle. An optical-mechanical scanning platform with fast 2D beam scanning is integrated into the 360-GHz terahertz wave imaging system

High-accuracy optical satellites may be severely impacted by microvibrations. We propose a simulation and measurement method without an image criterion to evaluate microvibrations that is characterized by low cost and early intervention in a satellite project schedule. First, the relation between image shift value and image quality is identified. Second, frequency response analysis and an optical amplification

The effect of a defective mode layer of GaAs semiconductor material of one-dimensional nonlinear photonic crystal, which is a function of intensity as well as the wavelength, is numerically simulated using transfer matrix method. It is observed that the transmission efficiency of this defective layer increases with an increase in the wavelength of the material. At the first transmission window (820

WO3 thin films evaporated on unheated substrates were found to be substoichiometric and microcrystalline in nature as found by the ellipsometric studies, density, and porosity measurements. In this investigation, we measured the optical constants of WO3 thin films and of MxWO3 (M = H + , Li + , and Na + ) bronzes (with different concentrations, x) after being annealed at different temperatures over

We proposed a subaperture stitching method for concave–convex microstructured surfaces. The method is mainly based on wavelet transform (WT) and three-dimensional (3D) data matching. WT is applied to separate the high-frequency information from the low-frequency information, then the speeded-up robust feature-random sample consensus algorithm is used to match 3D surface data and calculate lateral displacement

Recently, much attention has been paid to optical components with complex surfaces because they can significantly optimize the aberrations of optical systems. However, a complex surface introduces several difficulties for precise measurement. To address this challenge, we propose tilted-wave point diffraction interferometer (TPDI) for measurements of complex surfaces. TPDI combines the advantages of

Polarization navigation is an autonomous navigation method that relies on stable polarization patterns in the sky. The polarization sensor for navigation is composed of a CMOS image sensor (CIS) and four-direction metal nanograting. The optical conversion deviation of the CIS and the transmittance deviation of metal nanograting are the main factors affecting the angle measurement accuracy of the polarization

A simplified theoretical model that describes the formation of a gas bubble on a light-absorbing microinclusion in liquid during laser irradiation is presented. The experimental results of irradiation of agglomerates of carbon black nanoparticles with nanosecond laser pulses in distilled water and aqueous solution of glycerol are obtained. The satisfactory correspondence between the experimental and

This is a list of reviewers who served Optical Engineering in 2020.

We present a system that displays an image of any metal structure in a scene by the use of microwave radiation from a cavity resonator in a 10-GHz frequency band. An 80 mm × 80 mm mushroom-like electromagnetic band gap (EBG) structure was arranged, designed, analyzed, and integrated with an X band monopole antenna and the designed EBG monopole antenna has ∼2-GHz bandwidth. Meanwhile, a cubic cavity

A fixed wavelength optical parametric amplifier laser was constructed to create nanosecond pulsed light at 1527 nm for eye-safe range gated active short-wave infrared (SWIR) imaging. The laser pulse is generated using a Nd:YAG operating at 1064 nm to pump a potassium titanyle arsenate crystal in a single-pass geometry, resulting in ≈85 mJ at up to 28 Hz at 1527 nm with a pulse duration of ∼8 ns. The

We address an approach called “DepthFuseNet” for the fusion of thermal and visible images using convolutional neural networks (CNN). The thermal image acquires radiating energy of the sensed objects and hence it can easily distinguish the objects from its background. However, the visible image (i.e., the image acquired within the range of visible wavelength of electromagnetic spectrum) provides a more

High resolution and wide field of view (FOV) are always the goals of imaging, which are related to the space-bandwidth product (SBP) of the system. Currently, most methods focus on either resolution enhancement or FOV extension. Few works pay attention on both. There lacks a generalized framework for the joint space-frequency SBP expansion. We propose such a holographic imaging method, termed phase-space

Toward greenfield time and wavelength division multiplexed passive optical network (TWDM-PON) deployment in access segment, optimal network planning, and resource provisioning need to be explored in the planning phase to reduce capital expenditure (CapEx) and operational expenditure (OpEx). To address the issue, we propose an integer linear programming (ILP)-based optimization framework to design cost-efficient

A simplified entanglement-based quantum secured direct communication system over optical fibers is proposed. Instead of the complicated optical and electronic devices used in the transmitter of standard systems for security checks, a decoy-state generator is integrated with the encoder. This provides a simple yet efficient and easy to implement solution to reveal the presence of intruders. A significant

The performance of a bidirectional silicon mode-division (de)multiplexer has been analyzed in the radio over fiber passive optical network system. The device uses two grating-assisted contra-directional coupler sections to demultiplex the transmitted fundamental, first-order, and second-order quasi-transverse electric (TE) modes. A bandwidth of 791 GHz and acceptable crosstalks of −25.73 dB (TE0m)