We proposed and experimentally demonstrate a calibration method to estimate the position and the orientation of the anisotropic near point LED light source from a single view. In this work, a Lambertian sphere is used as the calibration target, where the reflection model of the Lambertian sphere under the illumination of LED with given radiant intensity distribution is analyzed theoretically to establish

Optical super-resolution microscopy can break the diffraction limit in far-field imaging to achieve nanoscopic resolution. Nowadays, super-resolution imaging based on saturated excitation exhibits great potentials in extracting high-frequency components. Current saturated absorption competition (SAC) method is based on spatio-temporally modulating the incident laser beams and demodulating the target

Full-color holographic three-dimensional (3D) projection technology is an important research direction in the field of holographic 3D display, which is committed to providing the viewer with 3D impression and color experience. A simple encoding method of generating a phase-only hologram (POH) for low crosstalk full-color multi-plane holographic projection is proposed. Multiple two-dimensional (2D)

As a key step in active structured light reconstruction technology, the phase unwrapping algorithm has a direct impact on improving measurement accuracy and efficiency. A fast adaptive phase unwrapping algorithm based on improved bucket sorting (PUIBS) is proposed, which effectively improves the relative performance of the measurement system. First, the unreliability function of a pixel is defined

Phase measurement profilometry plays an important role in industrial applications. Traditional fringe projection profilometry (FPP) requires a stable reference plane to record the reference phase for the 3D reconstruction, which makes it sensitive to the motion-induced error caused by the reference plane. Thus, it is challenging for the traditional FPP to implement a robust measurement in industrial

The three-dimensional digital image correlation (3D-DIC) method featuring two synchronized cameras has been widely used in the field of experimental mechanics to measure full-field 3D shape and deformation. However, the requirement of two synchronized cameras often limits the application of the regular 3D-DIC method. This study proposes a single-camera 3D-DIC system based on a fiber bundle (FB), aiming

Ghost imaging based on deep learning (DLGI) usually employs a supervised learning strategy, and needs a large set of labeled data to train a neural network. However, in many practical applications, it is difficult to obtain sufficient numbers of labeled data for training and the training process often takes a long time. Thus, a computational ghost imaging method based on deep learning using an untrained

Unlike optical elements, medium such as tissue usually has several polarization properties simultaneously. So it is desirable to identify the existence of types of optical behaviors and determine their values from measured Mueller matrices. In this work, we will review the methods of decomposing the macroscopic Mueller matrix and differential Mueller matrix in order to quantify polarization properties

Stereo cameras have been widely used for three-dimensional (3D) imaging, and their performances are highly depended on the calibration accuracy. This paper presents a marked-crossed fringe pattern for the calibration of stereo cameras. Some coded markers are also encoded into the crossed fringe pattern, and the feature points are encoded into the carried phase. Two wrapped phase maps are recovered

In this paper, we present a two steps phase-shifting fringe pattern demodulation method using the VU factorization. Compared with other methods, our proposal is robust to non-constant background illuminations and modulating terms (non-normalized fringes). We use the two given fringe patterns, and from these, we synthetically generate another two images that approach the background illumination in order

We demonstrate a novel scheme for a full-field optical coherence tomography (FF-OCT) system using a tunable-path-difference source (TPDS). Recently, the comb-spacing-swept source (CSWS) method, including TPDS, has been successfully applied to improve the stability of three-dimensional (3D) time-domain (TD)-FF-OCT imaging by eliminating the mechanical scanning of the reference path, which has been the

A single-exposure microscopic profilometry using artificial neural network (ANN) was developed for 3-D profile reconstruction of precise surface geometry. Optical profilometry is an important technique widely applied in many fields. However, in addition to optical aberration of the microscope itself, tilting of a local testing surface can affect the direction of the reflected light, thus causing undesired

We propose 2D gratings with 2D sinusoidal-like transmittance for spectral analysis in a wide wavelength range. Our design deploys the concept of the multiplicative superimposition of two mutually inclined or orthogonally crossed 1D binary amplitude gratings with appropriately selected opening numbers. In result the trapezoidal transmittance function without the 3rd and even harmonics is obtained in

High numerical aperture (NA) metalenses with large focusing efficiency are crucial for various applications in modern optics and photonics, particularly in high resolution imaging, high directivity lasing process and so on. Recent progresses have been achieved in designing high NA metalenses which can surpass conventional ones but mainly in the visible and infrared regimes by using all-dielectric metasurfaces

Thermal-mechanical coupling deformation is inevitable in the operation of materials and structures. Traditional deformation researches have mainly focused on temperature or deformation measurement at a specific temperature, but few studies have investigated the coupling relationship between temperature and deformation in a non-uniform thermal environment. This study presents a novel method of measuring

Our aim is to give free-viewpoint photo-realistic rendering of real indoor scenes, using a sparse collection of RGB-D image as input. Image based rendering (IBR) is an effective way to achieve both realism and interactivity. However, there are several challenges for IBR: misalignment of object boundaries between color-and-depth image pairs often leads to ghost contours; projection errors result in

Deflectometry is a non-contact optical technique which uses a simple system setup to measure and inspect specular surfaces. Conventional deflectometry methods usually need very complicated system calibration and time-consuming phase-shifting methods, which are not practical for high-speed measurement. But if the measurement target is a quasi-plane surface where the local slope is directly modulated

By virtue of its versatile recording geometries, ptychography is a promising full-field lensless phase imaging approach in the prosperous research area of terahertz imaging. In this paper, we propose an extrapolation extended ptychographical iterative engine, named as the EE-PIE reconstruction algorithm, to increase the lateral resolution of terahertz ptychography. A divergent spherical beam is applied

Structured-light (SL) three-dimensional (3D) shape measurements technique has been extensively studied and applied in various fields, but the real-time capability of SL system is limited by the number of projected SL patterns. This paper presents a digital image correlation (DIC) assisted phase matching and triple-scanning method for high-speed and accurate 3D shape measurements based on the combined

Various techniques exist for characterizing a birefringent fluid by means of extinction angle and birefringence. We summarize these techniques and present a new procedure. The approach derives the first three Stokes parameters from images of a polarization camera and uses them to calculate the corresponding streaming birefringence by applying the Mueller matrix calculus. The required theory and a suitable

Optical and photonics techniques such as computer-generated holograms (CGHs) are suggested to be used in security applications. In this paper, we present an approach to generate an authenticable phase-only hologram (APOH) for steganographic optical image encryption with phase optimization. The phase hologram can be calculated by the proposed integrated two-stage optimization method where Fresnel domain

In the digital speckle pattern interferometry (DSPI), accurate phase unwrapping is essential for quantitative phase measurement. In this paper, a novel adaptive mask generating algorithm based on the fuzzy set theory is proposed, which can automatically calculate an optimal threshold for the reliability masked weighted least-squares phase unwrapping. The reliability map of a wrapped phase map is firstly

In this paper, we demonstrate a convenient method to obtain the phase characterization curve of spatial light modulator (SLM) using polarimetry. Unlike existing polarimetric methods, the proposed method requires less number of intensity measurements. The generation of singular light fields through on-axis phase modulation has been demonstrated by ensuring a spatially uniform and linear phase response

Improving measurement accuracy over a wide range is very important for the measurement system based on four-quadrant detector (4QD). However, its measurement performance is easily affected by the energy distribution of the spot imaged on 4QD, which limits its wider practical application. Existing methods mainly use the collected data for curve fitting to improve the measurement accuracy. However, actual

The full-field and non-contact measurement of three-dimensional motion and deformation of high-speed rotating machinery is a very challenging task in the engineering field. Two issues, the cost of high-speed camera and the decorrelation between rotated images, are hard to avoid for investigators. In this paper, a systematic solution is presented, which combines high-speed rotation image acquisition

In the Fresnel regime, super-resolution multi-plane phase retrieval (MPPR) often requires upsampling the captured diffraction patterns via experimental or computational means to satisfy the sampling conditions imposed by the traditional angular spectrum method which quickly becomes computationally expensive for large upsampling ratios. Furthermore, the vanilla single-beam multiple-intensity reconstruction

High-temperature mechanical tests coupled with Digital Image Correlation (DIC) on ceramics which exhibit rather low level of strain require to overcome extreme experimental conditions that usually can reduce significantly measurement accuracy. Thermal resistance of speckle pattern, black body radiation and heat haze are three main concerns, which should thus be taken into account while designing a

Laser shock imprinting (LSI) technology has attracted more and more researchers' interest in the fabrication of high-precision three-dimensional (3D) microstructures. These researchers found that LSI technology can improve the depth, accuracy, and mechanical properties of the formed parts. However, they also found that when the formed parts made of LSI are used in high temperature environment, the

This paper reveals and compares the detection uncertainty of fractional optical vortex (FOV) in several coordinate transformation-based OAM sorting systems. It is found that the azimuth of the phase mutation of FOV will significantly affect the output results. Hence, there will be a detection uncertainty when analyzing FOV with angle indeterminacy, but this uncertainty is not come from the FOV itself

Digital holography is a three-dimensional (3D) measurement technique that can be used to quantitatively determine the size and 3D location of the objects inside a field-of-view. However, in systems where refractive index gradients are present, variations in optical phase due to high-speed shock-waves or low-speed thermal gradients can cause distortions that obscure objects. While techniques like phase-conjugate

Dioptric power measurement is classically achieved using manual focimeters. In this contribution, we present vectofocimetry as a novel methodology to be easily implemented in manual focimeters for improving their capabilities regarding dioptric power measurement. The new procedure is conceptually based on power vector formalism of dioptric power which represents the dioptric power as three values in

Non-mechanical optical beam steering has received extraordinary attention in recent decades because it can steer a beam to a desired direction or location without moving parts. As a novel member of the non-mechanical beam steering method family, the liquid-based beam steering method exhibits some intriguing features. For example, this method is polarization-independent and has wide broadband, low power

As for photometry analysis, increasing the optical-path (OP) via multi-reflection is an effective method for improving the detection sensitivity. In this paper, a photometer based on axial multi-reflection between two end-faces of capillary was proposed and investigated. The probe light can be back and forth reflected inside the capillary, by employing apertured silver-mirrors at both ends of a metal-capillary

A novel holographic femtosecond laser parallel processing method based on the fractional Fourier transform is proposed, which increases the flexibility of the processing position of the parallel beam as well as the available space in the paraxial area. Computer-generated holograms are produced by combining the fractional Fourier transform and an iterative algorithm with excellent uniformity and diffraction

The synthetic aperture technology can improve the resolution effectively in the optical imaging system. In fact, the imaging blur, turbulence aberration and noise can affect the imaging quality of optical synthetic aperture imaging system seriously. Several non-blind methods are applied generally to recover the degraded maps with the prior information. However, the restoration effect is not stable

A compact modulation transfer spectroscopy (CMTS) module with high stability in frequency and robustness is realized for a transportable 87Rb atomic gravimeter. The module is fabricated in a 91 mm×169 mm×60 mm box. The frequency instability achieved with CMTS is below 1.3×10−13/τ in the short term, not exceeding 5×10−12 until 1×105s, which is the best performance of 87Rb recorded so far in the literature

We present a new type of optical convolver / optical correlator capable of encoding higher orders. The technique is based on obtaining higher powers of a properly designed hologram. This can be obtained in two ways. First, we can recalculate higher orders of the amplitude and phase hologram in a standard spatial light modulator (SLM). More easily, we can utilize a phase-only hologram and exploit the

To satisfy the requirements of precision angle measurement and machine leveling, a high-sensitivity dual-axis optoelectronic level using double-layer liquid refraction is proposed in this paper. Silicone oil, with a constant horizontal surface, is used as a reference. A double-layer liquid refraction principle is used to improve the level's sensitivity. An autocollimator is used as a detector of two-dimensional

Deep understanding of biological superposition compound eye provides great opportunities in developing imaging systems with features beyond current planar detector array based imaging devices. However, artificial superposition compound eyes are designed on the basis of a planar detector array and that subsequently leads to the complex optical design and degradation of imaging quality inevitably. We

A Mueller matrix polarization parameter tomographic imaging (MMPPTI) in backscattering configuration for generating the depth-resolved cross sectional images of the polarization parameters of biological tissue is described. First, a theoretical model is proposed, which can be used to directly determine the polarization properties of anisotropic medium from the measured Mueller matrix. Several polarization

Final optics of high energy laser facilities are susceptible to laser-induced damage that reduces the quality of laser beams. In such facilities, images of protection windows are acquired on a daily basis. However, some motions may occur in addition to illumination changes. A method based on registration principles is developed to detect and quantify laser damage sites, which leads to sub-pixel resolution

Local strain measurement techniques, such as strain gauges or extensometers, have been broadly utilized as input data source for thermoelastic effect model identification in fiber-reinforced polymers, despite their well-known high heterogeneity. This experimental setup strongly limits the possibility of assigning thermoelastic models in a local-based manner for posterior Thermoelastic Stress Analysis

In this paper, we propose a new technique to achieve 360° panoramic large deformation measurement with the help of trinocular digital image correlation (3DT-DIC) system assisted by two mirrors. Two reflecting mirrors can image the rear of the specimen with virtual reality (secondary reflection). The trinocular vision system simultaneously captures the deformation images of the front and rear of the

In-line digital holography is a simple yet powerful tool to image absorbing and/or phase objects. However, the holograms of interest are corrupted by the background signal due to unwanted scattering elements located in the optical path. Using only two holograms of the same object, shifted to different locations, an inverse problems approach is applied to jointly estimate the complex transmittance of

A depth slice image that is computationally reconstructed from an integral imaging system consists of focused and out of focus areas. The unfocused areas affect three-dimensional (3D) image analyses and visualization including 3D object detection, extraction, and tracking. In this work, we present a deep learning integral imaging system that can reconstruct a 3D image without the out of focus areas

Incoherent Pattern-illuminated Fourier ptychography (IFP) is a newly developed super-resolution method, where accurate prior knowledge of translation positions is essential for image reconstruction. To release this limitation, we propose a pre-processing algorithm capable of extracting translation positions of the structure light directly from raw images of IFP, termed translation position extracting

Heterodyne efficiency reflects the matching states of phase and amplitude between a local oscillator (LO) beam and a received signal beam and is, therefore, an indicator of system performance. Many factors can cause sensitivity degradation or decoherence in active heterodyne detection applications, such as target speckle, atmospheric turbulence, and optical system aberrations. This paper presents a

Holographic reconstruction is affected by the phase-conjugate wave arising from the symmetry of the complex field. Compressive sensing (CS) has been used in in-line digital holography (DH) to eliminate noise, especially the interference from twin images. Herein, CS with total variation regularization combining autofocusing is presented. It provides an autofocusing function from a single-exposure hologram

Mueller matrix polarimetry can provide abundant microstructural information of tissues. Mueller matrix polar decomposition (MMPD) is capable of extracting intrinsic polarimetric characteristics of tissue-like media, including the orientation of the linear birefringence axis. However, when measuring a multi-layered sample with linear birefringence of different orientation directions, there is a deviation

Characterizing the nonlinear optical properties of various materials plays a prerequisite role in nonlinear optics. Among different measurement methods, the well-known Z-scan technique and the modified versions have been recognized as simple and accurate methods for measuring both the real and imaginary parts of the nonlinear refractive index. However, the Z-scan methods based on detecting small beam

We propose a super-resolution (SR) infrared imaging method with a multi-receptive field information distillation network. We develop a parallel progressive feature purification model to optimize the feature extraction progress and retain feature in each dimension. We use the dilation convolution to enlarge the network's receptive field and keep the number of parameters steady. We reconstruct a SR infrared

In general, infrared (IR) images are generated based on the temperature distribution of the objects of interest by detecting the thermal IR radiation emitted from these objects with the help of sensors. However, the generation of information-specific IR images can enable “intelligent” entities such as autonomous vehicles and artificial intelligence robots with IR detection features to use IR images

A closed-loop laser additive manufacturing (CLAM) system was developed to monitor and control layer-by-layer fabrication via directed energy deposition (DED). The well-modified laser additive manufacturing (LAM) package utilizes a thermal infrared camera and thermal image processing algorithms to extract and control the thermal dynamics of the process, including (i) cooling rate, (ii) melt pool temperature

Rapid material development is a new approach to reduce the time and cost intensity. It is based on small and simple sample geometries. Many conventional test methods such as hardness measurements or tensile tests are not suitable for this approach, because they either require a sample geometry adapted to the test method or they are time-consuming. Thus, research is being conducted on a novel impact-based

Brownian ratchet has emerged as a promising tool for deeply understanding motion mechanism of molecules and proteins, and dynamically manipulating particles in non-equilibrium thermodynamics state. Here, we propose and experimentally demonstrate a new type of optical Brownian ratchet, as generated by controllable phase profiles in holographic optical trapping system. The potential energy profiles are

Arbitrary distance and angle measurement play an important role in the intelligent industry, where accuracy and measurable range are critical for determining the object position in large-scale manufacturing scenarios. Using the dynamic comb spacing with long delay lines, we experimentally demonstrate dynamic dispersive interferometry, which performs high-accuracy measurement for arbitrary distances

This paper presents a complete procedure for the non-destructive analysis of composite laminates, taking advantage of the step-heating infrared thermography and the latest developments of deep neural networks. One-dimensional temperature profiles of the target surface are collected in response to long heat pulses and individually feed a compact network made of convolutional filters, self-tuned to represent

Fringe pattern based measurement techniques are crucial both in macroscale, e.g., fringe projection profilometry, and microscale, e.g., label-free quantitative phase microscopy. Accurate estimation of the local fringe density map can significantly facilitate almost all stages of fringe pattern analysis process. Example includes: (1) using density map as a determinant for the selection of the proper

We propose a new method to secure 3D color object using the holographic imaging spectroscopy technique. First, the original 3D color object is illuminated with a super-continuum white laser source with no necessity to decompose 3D color object into RGB components in advance which is commonly a preprocessing operation in traditional monochromatic illuminated optical cryptosystem. The output spectrum

Diseases often initiate from a certain layer of the biological tissue, thus simultaneous measurement of the elastic modulus of each layer is important for early diagnosis and treatment of various diseases. A surface wave spectroscopy (SWS) optical coherence elastography (OCE) technique based on harmonic wave excitation was proposed. An actuator consisting of a piezoelectric stack with a pin was designed