Digital volume correlation (DVC) method is extensively used for the internal displacement measurement. In biomechanical experiments, fluorescent beads are used, instead of traditional speckles (or microstructure of materials), as the information feature of the volume image for DVC algorithm. The traditional experimental method and DVC algorithm, together, provide an effective measurement method for

In this paper, an optical color image encryption scheme based on fingerprint key and three-step phase-shifting digital holography is proposed. In the proposed encryption scheme, the fingerprint is served as secret key directly, and the random phase masks generated from the fingerprint using secure hash algorithm and chaotic map are just used as interim variables. With the help of the fingerprint-based

The light field sectioning pyrometry (LFSP) has proven a significant advancement for in-situ measurement of flame temperature through a single light field camera. However, the spatial resolution of LFSP is limited, which severely inhibits the measurement accuracy. This paper aims to evaluate the spatial resolution of LFSP for flame temperature measurement quantitatively. A theoretical model of the

In the proposed work, a two-dimensional photonic crystal fiber (PCF) based on the surface plasmon resonance (SPR) refractive index sensor has been demonstrated and designed which is so much helpful to gain a better sensitivity response in urine observation. In order to detect the pregnancy, the simulation and analysis have been performed in both normal and pregnant urine with the effective refractive

The limited depth-of-field (DOF) in optical microscopic imaging systems prevents them from capturing an entirely focused images when the imaged scene is thick and covers a wide range of depth. Specimens lying outside the DOF is defocused and thus blurred, hindering the subsequent observation and analysis. Extended focused imaging aims at yielding a single all-in-focus image by combining the in-focus

The currently available area array imaging spectrometer fails to provide high spectral resolution and fast imaging under a wide field of view (FOV). Therefore, this study proposes an integral field imaging spectrometer (IFIS) that uses an image-space telecentric lens (ISTL), a mask, and lenslet array (MLA) as the front structure of the system. The influence of their structural parameters on the optical

Single pixel three-dimensional (3D) imaging technique has attracted lots of attention owing to its potential capability of working in a wide waveband. In this work, the single pixel 3D imaging is realized with the assistance of phase-shifting fringe projection. The deformed fringe images are recorded with the passive single pixel imaging technique, and the 3D information of the object is calculated

We reported a new method for measuring the optical power of fast and ultrafast laser pulses. This type of measurements usually encounters some technical difficulties in field of experimental practice. The method is based on investigating the laser-induced photoacoustics (PA) inside a non- lambertian integrating sphere made of stainless steel. The measured laser beam is introduced inside the sphere

Dispersion is a very common phenomenon in the broadband optical systems. Chromatic confocal technology uses the chromatic aberration of lens to decode the axial displacement of the sample surface by the focus-wavelength of the reflected spectrum. Dispersion characters of the light source and sample surface greatly influence the reflected spectrum except the useful chromatic aberration, leading to focus-wavelength

Recently, a method for measuring phase steps in real-time from a dynamic interferogram within the range (0,2π) has been presented. It was named Dynamic Volume Enclosed by a Surface (DVES) method and was built on a very well known algorithm of type self-calibrating generalized phase-shifting interferometry relied on geometric concept of volume enclosed by a surface (VES), which is enough fast, and accurate

Multimode fiber (MMF) plays a vital role in promoting the miniaturization of endoscope. However, real-time and high-definition imaging using the MMF that remains a challenging research. Traditional phase compensation and transmission matrix methods are affected by fiber shape and optical devices, which results in low imaging rate and accuracy. Deep learning can be used to construct the inverse transformation

Single pixel imaging is an innovative imaging scheme using active light to obtain spatial information, which has attracted much attention in the computational imaging field. However, for single pixel imaging, it is a great challenge to find an efficient technique to obtain imaging results with high quality under low sampling conditions. In order to solve this problem, a Fourier single pixel imaging

We propose a method for dielectric microparticles size measurement based on the temporal evolution of speckle pattern. We conducted experiments using aqueous suspension of different standard spherical latex particles that span a size range between 5 µm and 100 µm. To analyze the speckle pattern data, we use different and independent qualitative and quantitative algorithms. We built calibration curves

Laser speckle contrast imaging (LSCI) has been widely used for mapping blood flow. LSCI is well known to be highly sensitive to movement artifacts. Previous studies attempted to register the global misalignment by using raw speckle images and rigid registration algorithm. However, it is difficult to correct the local non-rigid motion only by using granular raw speckle images, especially in the tissue

The accuracy of camera calibration depends significantly on the control point detection which customarily subjects to image noise, distortion and resolution. This paper uses concentric circle grids as the calibration pattern and accordingly proposes a robust and accurate control point detection method for camera calibration. Each set of concentric circles on the grids pattern consists of multiple circles

Monitoring of extreme dynamic loadings on composite materials with high temporal and spatial resolution provides an important insight into the understanding of the material behaviour. Quantitative measurement of the surface strain at the first moments of the impact event may reveal the initiation of the failure mechanisms leading to damage. For this purpose, we developed a shearography instrument for

This paper presents a calibration parameters refinement specifically for a fringe projection profilometry system to assure the final accuracy, even when using an imperfect calibration target. Unlike existing camera-projector calibration methods, we arrange a refinement in subsequent process of target measurement. Following the trend of additionally estimating the target’s geometry, a novel formulation

The reconstruction of high-quality images from limited angular sparse-view tomography data is desired in many fields, including low-dose computed tomography and nondestructive detection. In this study, two regularization terms based on the assumptions of image continuity and nonzero pixels are utilized to reconstruct an image from incomplete data. By transforming the original nonlinear reconstruction

Industrial photogrammetry systems commonly require multiple coded targets to establish a global coordinate frame for relatively large objects. However, there are many industrial products that do not allow coded targets to be placed on their surfaces. We propose an accurate and dense point cloud generation approach for measuring large-sized, untextured objects. Unlike most existing industrial measurement

In various laser applications with multiple beams, measuring the pointing errors of different beams is a prerequisite. Normally, this is done by multiple measurements of corresponding laser spots after separating each beam. In this study, a neural network method is utilized to predict the position and angular errors of dual lasers from a single superimposed spot image on a tilted detector, and thus

PZT is commonly used as the phase shifter in interferometric systems with small apertures for decades. However, it becomes more difficult to be applied to the system with large aperture. In this paper, the phase shifting procedure is moved to the source module with a low coherence laser, which makes phase shifting independent of the large interference cavity. The path matching procedure based on intensity

In this paper, we proposed a new method that combines virtual structural-modulated (VSM), line-scanning microscopy (LSM) and the Fourier ptychography (FP) algorithm to rapid super-resolution imaging. VSM provides an easy, low-cost and phase-artifact-free strategy to achieve super-resolution imaging. However, the practical application of this method is challenging due to a limited image acquisition

Fully printed microsensors are widely used in daily life to monitor various parameters of health, environment, and food, etc. However, the fabrication of fully printed microsensors still suffers from multiple procedures and excessive devices. Herein, a facile approach using combinational laser micromachining techniques with the same laser is developed to fabricate fully printed microsensors. Three

Optical Character Recognition (OCR), which is generally based on figure recognition, is mainly effective for extracting text from pictures. However, it is a challenge to maintain a high recognition rate without being affected by light interference in a complicated environment. To reduce the light interference for improving the OCR recognition rate, this article proposes a method utilizing single-pixel

High-speed and high-accuracy measurement is the ultimate objective of fringe projection profilometry(FPP). However, improving measurement speed, especially without the reduce of measurement accuracy, poses a great challenge for the development of FPP. In contrast to the existing methods, which typically use phase unwrapping method, this paper proposes a high-speed and high-accuracy FPP without phase

In this paper we report successful integration of digital holography in off- axis transmission configuration into a commercially available pathology microscope (PathologyDHM), where Mach-Zehnder interferometric configuration was achieved in pathology microscope using 1 × 2 single mode fiber coupler and custom built optical modules. A smartphone/webcam positioned at the image plane of the finite conjugate

We present the design, performance, and initial activation of the Mobile Ultrafast High Energy Laser Facility, a 5 TW near-infrared laser source located on a multi-km test range at Kennedy Space Center. The system is compact, readily transportable, and provides a robust, tunable output suitable for long range studies of high intensity laser propagation. The supporting testing infrastructure, which

Dilution is an unavoidable consequence of multi-material fusion processing, i.e. welding, cladding etc. In this paper we propose a novel method for controlled dilution experiments, analyzing microstructural trends of steel filler wire diluted with steel base metal. The highlight of this method is the control of processing conditions used to melt a pre-determined dilution of two high strength steels

Grating tiling is an important fabrication technology for large-size gratings. However, when using grating tiling technology to form large-size echelle gratings, the interferometer cannot detect the grating's zero-order diffraction wavefront because the zero-order diffraction light of the echelle grating is weak. This prevents use of the zero-order and non-zero-order diffraction light of the grating

The Rotating synthetic aperture (RSA) is one of the most promising novel imaging systems to meet the requirements of lightweight and high resolution for optical remote sensing satellites, especially in geostationary orbit. The point spread function (PSF) orientation relative to the observed scene, intentionally changes to measure all spatial frequency information available to a filled circular aperture

The reported laser welding of dissimilar materials (metal and plastic) mostly focuses on the optimization of parameters and process, the process is complex and the cost is high. Liquid crystal polymer (LCP) has attracted much attention due to its excellent electrical properties. With the rapid development of information technology, 5G high-frequency communication is gradually emerging. At the same

A high-efficiency coherent imaging system is designed by using phase modulation. After rotating a known phase mask, three images from rotation modulation are recorded and utilized to accurately reconstruct the complex-value sample. Specially, the system is free from rotation angle calculation, and requires fewer intensity measurements. This method has a superiority in convergence speed and calculation

Accuracy of digital image correlation (DIC) is deeply affected by illumination variation, especially the local pixel saturation exists. A simple and efficient gray intensity adjustment strategy based on feature matching and standard DIC method is presented for estimating the intensities of saturated pixels. Principle of the strategy based on surrounding pixels around the saturated pixel and the principle

We present a novel approach of phase retrieval using a 4f-imaging system, for the specific case of spatially partially coherent illumination. The theoretical investigation presented in Part I is based on scalar diffraction theory in combination with a heuristic approach. We find that the intensity of the de-focused speckle fields across the image plane shows sufficient contrast for phase retrieval

Fiber Optic Shape Sensing is an innovative Optical Fiber Sensing Technology that uses a fiber optic cable to continuously track the 3D shape and position of a dynamic object (with unknown motion) in real-time without visual contact. This technology offers a valid alternative to existing shape sensing methods, thanks to a combination of advantages (including ease of installation, intrinsic safety, compactness

Remote laser-welding systems are being used more frequently because of their larger working areas, shorter downtimes and ability to weld different seam types with high accuracy at greater speeds in comparison to conventional welding. Therefore, precise process-monitoring methods are needed in order to achieve weld traceability and good process and quality control to accompany different welding situations

For laser-induced fluorescence (LIF), the SNR and related concentration detectability was severely limited by background signal (noise). Herein, an axial-excitation LIF based on pinhole metal-capillary (PMC) and direct laser-diode excitation was proposed. An overall ~480 fold improvement on SNR was realized, because the laser-sidewall interaction (LSI) and related background signal (noise) can be effectively

We propose a short U-net model with average pooling to restore in-focus images of multiple transparent particles at their ground truth z-positions, while simultaneously removing their zero-order images, conjugate images, defocused images of other particles, and the noise associated with the optical system. Subsequently, we obtain the lateral location and diameter of each particle efficiently, thus

Utilization of a complex-valued interference signal (CVIS) in a white-light scanning interferometer is a powerful method to measure exactly surface positions of a glass plate. In this method a zero phase position nearest to a maximum amplitude position in the CVIS is a measured surface position. Proportional coefficients that relate the maximum amplitude position and the zero phase position of a rear

Dispersion objective is the crucial device of chromatic confocal sensor (CCS). The dispersion range and numerical aperture (NA) determine the measurement range and the maximum measurement slope of CCS, respectively. In this paper, we present two kinds of initial structures of dispersion objective for CCS based on doublet lens, which are suitable for the design of dispersion objectives with large dispersion

In this paper, security of a nonlinear optical cryptosystem based on double random phase encoding (DRPE) is analyzed. In the cryptosystem, a time-varying nonlinear term is combined with the classical DRPE technique to enhance security. The advantages of the nonlinear term are its easy distribution and no effect on the decrypted image. Also, it is confirmed that the method is resistant to conventional

The phase type computer generated hologram (CGH) plays an important role in aspherical surface optical testing, especially for low reflectivity material mirror surfaces, owing to its high diffractive efficiency. With the increasing demand for high precision CGHs, traditional methods such as reactive ion etching and focusing ion beam, have difficulty realizing the fabrication of a large aperture and

The paper deals with the edge diffraction of the single charged Laguerre-Gaussian beam outside the waist. Based on the Kirchhoff-Fresnel integral, the behavior of the optical vortex (OV) migration during sequential beam blocking by the straight edge of the screen is performed analytically. Universal combination of the diffracting-beam parameters determining the shape for the OV spiral trajectories

In order to eliminate strong ambient noise affecting the detection performance of optical fiber vibration sensing system, a composite system is proposed in this paper, which merges Michelson interferometer (MI) structure, Mach-Zehnder interferometer (MZI) structure and phase-sensitive optical time domain reflector (Φ-OTDR) structure by optical path coupling and wavelength division multiplexing. The

The holographic diffuser plays a significant role in the reconstruction performance of the large-size integral imaging display system. However, the influence of the holographic diffuser on the display quality is seldom theoretically analyzed. In this paper, a quantitative beam analysis approach is proposed, and a diffusing model is established to analyses the influence of the position and diffusing-angle

Motion blurring often occurs during camera imaging process due to the relative motion between the scene and imaging sensor, which would degrade the quality of captured image. In this paper, an effective coded exposure photography framework is proposed to help obtain better motion deblurring results. An integrated optimal fluttering pattern generation criterion with several factors is designed to guarantee

Retaining structures are required to evaluate their stability not only during construction but also during maintenance. In this paper, the retaining structure was constructed after excavating the slope for the tunnel construction. In order to evaluate the stability of a large-scale retaining structure, laser scanning was applied to monitor the behavior of the retaining structure. Since the retaining

Structured light measurement system that consists of a camera and a projector has been widely used in three-dimensional (3-D) shape measurement. The premise of measurement is to calibrate the structured light system, and the calibration accuracy directly affects the accuracy of 3-D measurement system. The traditional calibration board-based methods suffer from either complex operations or uncompetitive

We propose a new approach for optical analog-signal transmission through multi-layer scattering media using single-pixel detector to achieve high peak signal-to-noise ratio (PSNR), and analog signals can be experimentally received with high PSNR through multi-layer scattering media. The proposed approach, experimental observation and optical experimental results are presented that intensity of the

In this research paper, we propose a novel one-dimensional chaotic system based on the fraction of cosine over sine (1-DFCS). Evaluation of 1-DFCS indicates the existence of a complex chaotic behavior, an infinite chaotic range, and a high initial state sensitivity. We further propose a new sensitive dynamic mutual image encryption scheme (SDME) using 1-DFCS. SDME is designed with a dynamic diffusion

Realization of deep learning with coherent diffraction has achieved remarkable development nowadays, which benefits on the fact that matrix multiplication can be optically executed in parallel with high band-with and low latency. Coherent optical field in the form of complex-valued entity can be manipulated into a task-oriented output. In this paper, a modulation mechanism is established by implementing

We experimentally demonstrate the shape measurement of micro objects by means of phase retrieval under spatially partially coherent illumination. This approach offers an extended depth of focus, vibration insensitivity, short measurement time and precise shape measurements, enables the use of spatially extended light sources such as LEDs and thus significantly improves the eye safety of the method

The focus error signal is a widespread optical technique that harnesses the shape of a simply astigmatic Gaussian beam to produce an output signal with a well-defined linear range used for many different applications. However, general astigmatic Gaussian beams have not been extensively used for measuring purposes even though they have been known for decades. These beams have interesting properties

We develop a novel kind of single-pixel imaging (SPI) scheme to reconstruct high-quality images of the axially fast-moving target by utilizing the non-diffracting beam illumination. In this paper, a kind of cosine shaped source is elaborately designed and introduced for the first time in the SPI scheme to realize the reconstruction of the dynamic target. The imaging formula for the SPI system with

On-line thickness monitor of thin film deposition by thermal evaporation is demonstrated using femtosecond pump-probe photoacoustics. A Ti:sapphire femtosecond laser (wavelength 800 nm, pulse width ~110 fs, pulse energy ~1.3 nJ) is split into a pump and a probe beams. The pump beam is used to instantaneously heat the illuminated area of an aluminum thin film during its deposition on a silicon substrate

Optical sphere covers are widely used in photogrammetric systems to protect camera systems from external conditions. The spherical refraction can cause severe non-linear distortion, resulting in imprecise and unreliable measurements. In particular the cameras with a relatively thick optical sphere cover (e.g. underground or underwater cameras). However, the conventional perspective camera model are

Environmental protection is today’s major issue in the development of turbomachines. Especially, the reduction of pollutant and noise emission of aero engines and ground based gas turbines for power plants is a central task. Therefore, an improved understanding of the occurring complex flow phenomena in such turbomachines is necessary, which requires the investigation of influence and interaction of

Compressed ultrafast photography (CUP), as the fastest receive-only ultrafast imaging technology by combining steak imaging and compressed sensing (CS), has shown to be a powerful tool to measure ultrafast dynamic scenes. Through a reconstruction algorithm based on CS, CUP can capture the three-dimensional image information of non-repetitive transient events with a single exposure. However, it still