Usage of moving nanoparticles for improved holographic recording

Metal nanoparticles are used for different applications in holographic configurations. The metal nanoparticles are placed close to an object and encode it by a time varying random mask. A decoding mask is computed and used to obtain super-resolution digital hologram and eliminate the twin image and DC from a digital hologram. The method is also shown to be applicable for other optical methods.

Coherent Microscopy for 3-D Movement Monitoring and Super-Resolved Imaging

In this chapter we present three types of microscopy-related configurations while the first one is used for 3-D movement monitoring of the inspected samples, the second one is used for super-resolved 3-D imaging, and the last one presents an overview digital holographic microscopy applications. The first configuration is based on temporal tracking of secondary reflected speckles when imaged by properly defocused optics. We validate the proposed scheme by using it to monitor 3-D spontaneous contraction of rat’s cardiac muscle cells while allowing nanometric tracking accuracy without interferometric recording. The second configuration includes projection of temporally varying speckle patterns…

Compact and Field Portable Biophotonic Sensors for Automated Cell Identification (Plenary Address)

In this Plenary address paper, we overview recently published work for automated cell identification using 3D optical imaging in compact and field portable biophotonic sensors. Digital holographic microscopy systems and lensless pseudorandom phase encoding systems capture 3D information of biological cells and make highly accurate automated cell identification possible. Overviewed systems include sickle cell disease diagnosis based on spatio-temporal cell dynamics in a field-portable 3D-printed shearing digital holography as well as lensless cell identification of both single and multicell samples using pseudorandom phase encoding.

Formation of real, orthoscopic integral images by smart pixel mapping.

Integral imaging systems are imaging devices that provide 3D images of 3D objects. When integral imaging systems work in their standard configuration the provided reconstructed images are pseudoscopic; that is, are reversed in depth. In this paper we present, for the first time we believe, a technique for formation of real, undistorted, orthoscopic integral images by direct pickup. The technique is based on a smart mapping of pixels of an elemental-images set. Simulated imaging experiments are presented to support our proposal.

3D integral imaging with optical processing

Integral imaging (InI) systems are imaging devices that provide auto-stereoscopic images of 3D intensity objects. Since the birth of this new technology, InI systems have faced satisfactorily many of their initial drawbacks. Basically, two kind of procedures have been used: digital and optical procedures. The "3D Imaging and Display Group" at the University of Valencia, with the essential collaboration of Prof. Javidi, has centered its efforts in the 3D InI with optical processing. Among other achievements, our Group has proposed the annular amplitude modulation for enlargement of the depth of field, dynamic focusing for reduction of the facet-braiding effect, or the TRES and MATRES devices…

Optimized integral imaging display by global pixel mapping

Integral imaging systems are imaging devices that provide 3D images of 3D objects. When integral imaging systems work in their standard configuration the provided reconstructed images are pseudoscopic; that is, are reversed in depth. In this paper we present a technique for formation of real, undistorted, orthoscopic integral images by direct pickup. The technique is based on a global mapping of pixels of an elemental-images set. Simulated imaging experiments are presented.

Free-depths reconstruction with synthetic impulse response in integral imaging

Integral Imaging provides spatial and angular information of three-dimensional (3D) objects, which can be used both for 3D display and for computational post-processing purposes. In order to recover the depth information from an integral image, several algorithms have been developed. In this paper, we propose a new free depth synthesis and reconstruction method based on the two-dimensional (2D) deconvolution between the integral image and a simplified version of the periodic impulse response function (IRF) of the system. The period of the IRF depends directly on the axial position within the object space. Then, we can retrieve the depth information by performing the deconvolution with compu…

Orthoscopic long-focal-depth 3D integral imaging

Integral imaging systems are imaging devices that provide 3D images of 3D objects. When integral imaging systems work in their standard configuration the provided reconstructed images are pseudoscopic; that is, are reversed in depth. In this paper we present, a technique for formation of real, undistorted, orthoscopic integral images by direct pickup. The technique is based on the use of a proper relay system and a global mapping of pixels of the elemental-images set. Simulated imaging experiments are presented to support our proposal.

Three-dimensional polarimetric computational integral imaging

In this paper, we propose a novel 3D polarimetric computational integral imaging system by using polarization diversity of objects under natural illumination conditions. In the system, the measured Stokes polarization parameters are utilized to generate degree of polarization images of a 3D scene. Based on degree of polarization images and original 2D images, we utilize a modified computational reconstruction method to perform 3D polarimetric image reconstruction. The system may be used to detect or classify objects with distinct polarization signatures in 3D space. Experimental results also show the proposed system may mitigate the effect of occlusion in 3D reconstruction.

Optically-corrected elemental images for undistorted Integral image display

Conventional macro objectives are generally used as relay systems in the capture stage in Integral Imaging. This choice leads to microimage overlap and shift, which produce undesirable effects on the reconstructed three-dimensional images, such as loss in resolution and image distortions. In this paper, we propose and demonstrate a new architecture for the capture stage. Our method uses a telecentric relay system to overcome the conventional drawbacks. Experiments conducted with our system show an important improvement in the quality of displayed images.

Extended View Angle Integral Imaging 3D Display using Smart Pseudoscopic-to-orthoscopic Conversion with Head Tracking

We overview a head tracking integral imaging display using the smart pseudoscopic-to-orthoscopic conversion method. The crosstalk for a large viewing angle in integral imaging is eliminated by generating a new set of elemental images.

Long working range light field microscope with fast scanning multifocal liquid crystal microlens array

The light field microscope has the potential of recording the 3D information of biological specimens in real time with a conventional light source. To further extend the depth of field to broaden its applications, in this paper, we proposed a multifocal high-resistance liquid crystal microlens array instead of the fixed microlens array. The developed multifocal liquid crystal microlens array can provide high quality point spread function in multiple focal lengths. By adjusting the focal length of the liquid crystal microlens array sequentially, the total working range of the light field microscope can be much extended. Furthermore, in our proposed system, the intermediate image was placed i…

On axis holography by random particles encoding

A method for eliminating the unwanted terms in an on axis hologram is presented. In this method, free randomly distributed nanoparticles are in proximity to the object and their Brownian motion encodes the spatial features of the object in the recorded hologram. The nanoparticles are localized and a decoding pattern is calculated for each frame. This decoding pattern is then used to remove the reference beam and the conjugate beam in the reconstruction of the hologram.

3D imaging and visualization: An overview of recent advances

This paper presents an overview of our published work on physical principles, applications, and advances in integral imaging and digital holography. Various approaches for image capture, image reconstruction, and 3D display methods are overviewed. Applications including 3D underwater imaging, 3D imaging in photon-starved environments, 3D tracking of occluded objects, 3D optical microscopy, and 3D polarimetric imaging are reviewed.

Three-Dimensional Integral Imaging and Display

Stable and simple quantitative phase-contrast imaging by Fresnel biprism

Digital holographic (DH) microscopy has grown into a powerful nondestructive technique for the real-time study of living cells including dynamic membrane changes and cell fluctuations in nanometer and sub-nanometer scales. The conventional DH microscopy configurations require a separately generated coherent reference wave that results in a low phase stability and a necessity to precisely adjust the intensity ratio between two overlapping beams. In this work, we present a compact, simple, and very stable common-path DH microscope, employing a self-referencing configuration. The microscope is implemented by a diode laser as the source and a Fresnel biprism for splitting and recombining the be…

Resolution enhancement and orders separation in on-axis nanoparticles based digital holography

A method for eliminating the unwanted terms in an on axis hologram is presented. Free randomly distributed nanoparticles are used to encode and later on to decode/separate the desired term from the unwanted aberrations.

Super Resolved Holographic Configurations

Non-Homogeneity of Lateral Resolution in Integral Imaging

We evaluate the lateral resolution in reconstructed integral images. Our analysis takes into account both the diffraction effects in the image capture stage and the lack of homogeneity and isotropy in the reconstruction stage. We have used Monte Carlo simulation in order to assign a value for the resolution limit to any reconstruction plane. We have modelled the resolution behavior. Although in general the resolution limit increases proportionally to the distance to the lens array, there are some periodically distributed singularity planes. The phenomenon is supported by experiments.

Super Resolution Methods Implementing Diffractive Masks Having a Certain Degree of Periodicity

This section presents an approach that provides super resolved imaging at the center of the field of view and yet allows to see the remaining of the original field of view with original resolution. This operation resembles optical zooming while the zoomed and the nonzoomed images are obtained simultaneously. This is obtained by taking a single snap-shot and using a single imaging lens. The technique utilizes a special static/still coding element and a postprocessing algorithmic, without any mechanical movements.

Fundamentals of 3D imaging and displays: a tutorial on integral imaging, light-field, and plenoptic systems

There has been great interest in researching and implementing effective technologies for the capture, processing, and display of 3D images. This broad interest is evidenced by widespread international research and activities on 3D technologies. There is a large number of journal and conference papers on 3D systems, as well as research and development efforts in government, industry, and academia on this topic for broad applications including entertainment, manufacturing, security and defense, and biomedical applications. Among these technologies, integral imaging is a promising approach for its ability to work with polychromatic scenes and under incoherent or ambient light for scenarios fro…

Phase-shifting Gabor holography.

We present a modified Gabor-like setup able to recover the complex amplitude distribution of the object wavefront from a set of inline recorded holograms. The proposed configuration is characterized by the insertion of a condenser lens and a spatial light modulator (SLM) into the classical Gabor configuration. The phase shift is introduced by the SLM that modulates the central spot (dc term) in an intermediate plane, without an additional reference beam. Experimental results validate the proposed method and produce superior results to the Gabor method.

Roadmap on 3D integral imaging: Sensing, processing, and display

This Roadmap article on three-dimensional integral imaging provides an overview of some of the research activities in the field of integral imaging. The article discusses various aspects of the field including sensing of 3D scenes, processing of captured information, and 3D display and visualization of information. The paper consists of a series of 15 sections from the experts presenting various aspects of the field on sensing, processing, displays, augmented reality, microscopy, object recognition, and other applications. Each section represents the vision of its author to describe the progress, potential, vision, and challenging issues in this field.

Breakthroughs in Photonics 2014: Recent Advances in 3-D Integral Imaging Sensing and Display

Integral imaging concept provides a fascinating tool for the capture and display of 3-D images or movies with full parallax, with no need for special glasses and without visual fatigue due to the convergence and accommodation conflict. The limitations and recent advances in integral imaging are discussed.

Algorithms for transforming an integral photography into a plenoptic picture

We report a simple algorithm for transforming the set of elemental images captured with an integral-photography set up, into the set of micro-images ready to be projected into an integral-imaging monitor. The method is based in the transposing relation between an integral photography and a plenoptic picture. The reported technique permits to adapt the integral images to the resolution and size of the monitor.

Fundamentals of automated human gesture recognition using 3D integral imaging: a tutorial

Automated human gesture recognition is receiving significant research interest, with applications ranging from novel acquisition techniques to algorithms, data processing, and classification methodologies. This tutorial presents an overview of the fundamental components and basics of the current 3D optical image acquisition technologies for gesture recognition, including the most promising algorithms. Experimental results illustrate some examples of 3D integral imaging, which are compared to conventional 2D optical imaging. Examples of classifying human gestures under normal and degraded conditions, such as low illumination and the presence of partial occlusions, are provided. This tutorial…

Head Tracking Three-Dimensional Integral Imaging Display Using Smart Pseudoscopic-to-Orthoscopic Conversion

A novel head tracking three-dimensional (3D) integral imaging display is presented. By means of proper application of the smart pseudoscopic-to-orthoscopic conversion (SPOC) method, our display allows an extended viewing angle accommodated to the viewer's position which is obtained by a head/eye tracking system. Using the SPOC, new sets of elemental images are calculated and adapted to any specific viewing position. Additionally, the crosstalk which is typical in conventional integral imaging, is eliminated for a large viewing angle. By performing the rotation transformation in the simulated display, viewing a 3D scene with head rotation can be realized for robust display. Experimental resu…

An overview of head tracking integral imaging three-dimensional display using smart pseudoscopic-to-orthoscopic conversion

We overview a previously reported head tracking integral imaging three-dimensional (3D) display to extend viewing angle accommodated to a viewer's position without the crosstalk phenomenon. A head detection system is applied to obtain the head position and rotation of a viewer, and a new set of elemental images is then computed using the smart pseudoscopic-to-orthoscopic conversion (SPOC) method for head tracking 3D display. Experimental results validate the proposed method for high quality 3D display with large viewing angle.

Superresolved and field-of-view extended digital holography with particle encoding

We present a new configuration for superresolution (SR) as well as for field-of-view (FOV) extension in a digital holography concept based on random movement of sparse metallic particles. In the SR configuration, the particles are in proximity to the recorded object, while in the FOV configuration, the particles are in proximity to the hologram plane. The particles' movement encodes the high spatial features in the plane of their movement. This high-resolution information can later be decoded by proper numerical postprocessing that either remedies the resolution limitations in the object plane (or the limited NA of the lens) or extends the FOV in the object plane.

Three-dimensional object-distortion-tolerant recognition for integral imaging using independent component analysis

Independent component analysis (ICA) aims at extracting unknown components from multivariate data assuming that the underlying components are mutually independent. This technique has been successfully applied to the recognition and classification of objects. We present a method that combines the benefits of ICA and the ability of the integral imaging technique to obtain 3D information for the recognition of 3D objects with different orientations. Our recognition is also possible when the 3D objects are partially occluded by intermediate objects.

Multidimensional optical sensing and imaging for displays, computational imaging, optical security, and healthcare

In this invited paper, we present an overview of our recently published work on 3D imaging, visualization and displays, including optical security using quantum imaging principles, 3D microscopy, healthcare, automated disease identification with 3D imaging, fatigue free augmented reality 3D glasses, and optical security and authentication using photon counting for IC inspection, polarimetric photon counting 3D imaging, and 3D human gesture recognition

Enhanced field-of-view integral imaging display using multi-Köhler illumination.

A common drawback in 3D integral imaging displays is the appearance of pseudoimages beyond the viewing angle. These pseudoimages appear when the light rays coming from each elemental image are not passing through the corresponding microlens, and a set of barriers must be used to avoid this flipping effect. We present a pure optical arrangement based on Köhler illumination to generate these barriers thus avoiding the pseudoimages. The proposed system does not use additional lenses to project the elemental images, so no optical aberrations are introduced. As an added benefit, Köhler illumination provides a higher contrast 3D display. This work was supported in part by the Plan Nacional I + D …

Digital Holographic Microscopy: A New Imaging Technique to Quantitatively Explore Cell Dynamics with Nanometer Sensitivity

In the first part of this chapter, we describe how the new concept of digital optics applied to the field of holographic microscopy has made it possible to quantitatively and accurately measure the phase retardation induced on the transmitted wavefront by the observed transparent specimen, allowing thus to develop a reliable and flexible digital holographic quantitative phase microscopy (DH-QPM). In the second part the most relevant DH-QPM applications in the field of cell biology are presented. Particularly, applications taking directly advantage of benefits provided by digital optics particularly off-line autofocusing and extended depth of focus, are outlined. Otherwise, special emphasis …

Optical security and encryption with totally incoherent light

We present a method for securing and encrypting information optically by use of totally incoherent illumination. Encryption is performed with a multichannel optical processor working under natural (both temporal and spatially incoherent) light. In this way, the information that is to be secured can be codified by use of color signals and self-luminous displays. The encryption key is a phase-only mask, providing high security from counterfeiting. Output encrypted information is recorded as an intensity image that can be easily stored and transmitted optically or electrically. Decryption or authentication can also be performed optically or digitally. Experimental results are presented.

Resolution improvements in integral microscopy with Fourier plane recording

Abstract: Integral microscopes (IMic) have been recently developed in order to capture the spatial and the angular information of 3D microscopic samples with a single exposure. Computational post-processing of this information permits to carry out a 3D reconstruction of the sample. By applying conventional algorithms, both depth and also view reconstructions are possible. However, the main drawback of IMic is that the resolution of the reconstructed images is low and axially heterogeneous. In this paper, we propose a new configuration of the IMic by placing the lens array not at the image plane, but at the pupil (or Fourier) plane of the microscope objective. With this novel system, the spa…

Elemental images for integral-imaging display

One of the differences between the near-field integral imaging (NInI) and the far-field integral imaging (FInI), is the ratio between number of elemental images and number of pixels per elemental image. While in NInI the 3D information is codified in a small number of elemental images (with many pixels each), in FInI the information is codified in many elemental images (with only a few pixels each). The later codification is similar that the one needed for projecting the InI field onto a pixelated display when aimed to build an InI monitor. For this reason, the FInI cameras are specially adapted for capturing the InI field with display purposes. In this contribution we research the relation…

Fully programmable display parameters in integral imaging by smart pseudoscopic-to-orthoscopic conversion

Previously, we reported a digital technique for formation of real, non-distorted, orthoscopic integral images by direct pickup. However the technique was constrained to the case of symmetric image capture and display systems. Here, we report a more general algorithm which allows the pseudoscopic to orthoscopic transformation with full control over the display parameters so that one can generates a set of synthetic elemental images that suits the characteristics of the Integral-Imaging monitor and permits control over the depth and size of the reconstructed 3D scene.

Roadmap on digital holography [Invited]

This Roadmap article on digital holography provides an overview of a vast array of research activities in the field of digital holography. The paper consists of a series of 25 sections from the prominent experts in digital holography presenting various aspects of the field on sensing, 3D imaging and displays, virtual and augmented reality, microscopy, cell identification, tomography, label-free live cell imaging, and other applications. Each section represents the vision of its author to describe the significant progress, potential impact, important developments, and challenging issues in the field of digital holography.

Multispectral integral imaging acquisition and processing using a monochrome camera and a liquid crystal tunable filter

This paper presents an acquisition system and a procedure to capture 3D scenes in different spectral bands. The acquisition system is formed by a monochrome camera, and a Liquid Crystal Tunable Filter (LCTF) that allows to acquire images at different spectral bands in the [480, 680]nm wavelength interval. The Synthetic Aperture Integral Imaging acquisition technique is used to obtain the elemental images for each wavelength. These elemental images are used to computationally obtain the reconstruction planes of the 3D scene at different depth planes. The 3D profile of the acquired scene is also obtained using a minimization of the variance of the contribution of the elemental images at each …

Automatic target recognition using 3D passive sensing and imaging with independent component analysis

We present an overview of a method using Independent Component Analysis (ICA) and 3D Integral Imaging (II) technique to recognize 3D objects at different orientations. This method has been successfully applied to the recognition and classification of 3D scenes.

Multiple-Planes Pseudoscopic-to-Orthoscopic Conversion for 3D Integral Imaging Display

In this paper, we propose an advanced pseudoscopic-to-orthoscopic conversion method for 3D integral imaging display systems. Compared to previous works, this method can generate more accurate images for orthoscopic 3D display using multiple reference planes and estimated depth information. 3D display results show the superiority of the proposed pseudoscopic-to-orthoscopic conversion method.

Relay optics for enhanced integral imaging

Integral imaging provides with three-dimensional (3D) images. This technique works perfectly with incoherent light and does not need the use of any special glasses nor stabilization techniques. Here we present relay systems for both acquire and display 3D images. Some other important challenges are revisited.

Multidimensional Optical Sensing and Imaging Systems (MOSIS): From Macro to Micro Scales

Multidimensional optical imaging systems for information processing and visualization technologies have numerous applications in fields such as manufacturing, medical sciences, entertainment, robotics, surveillance, and defense. Among different three-dimensional (3-D) imaging methods, integral imaging is a promising multiperspective sensing and display technique. Compared with other 3-D imaging techniques, integral imaging can capture a scene using an incoherent light source and generate real 3-D images for observation without any special viewing devices. This review paper describes passive multidimensional imaging systems combined with different integral imaging configurations. One example…

Multidimensional Integral Imaging for Sensing, Visualization, and Recognition in Degraded Environments

An overview of multidimensional integral imaging for sensing, visualization, and recognition in degraded environments is presented. Applications include 3D visualization, photon starved imaging, material inspection, IR imaging, passive depth estimation, automated human gesture recognition, and long-range imaging.

Enhanced depth of field integral imaging with sensor resolution constraints.

One of the main challenges in integral imaging is to overcome the limited depth of field. Although it is widely assumed that such limitation is mainly imposed by diffraction due to lenslet imaging, we show that the most restricting factor is the pixelated structure of the sensor (CCD). In this context, we demonstrate that by proper reduction of the fill factor of pickup microlenses, the depth of field can be substantially improved with no deterioration of lateral resolution.

Multifacet structure of observed reconstructed integral images.

Three-dimensional images generated by an integral imaging system suffer from degradations in the form of grid of multiple facets. This multifacet structure breaks the continuity of the observed image and therefore reduces its visual quality. We perform an analysis of this effect and present the guidelines in the design of lenslet imaging parameters for optimization of viewing conditions with respect to the multifacet degradation. We consider the optimization of the system in terms of field of view, observer position and pupil function, lenslet parameters, and type of reconstruction. Numerical tests are presented to verify the theoretical analysis.

Passive Polarimetric Imaging

Passive electro-optical polarimetric imaging is a form of remote sensing in which the properties associated with electromagnetic field orientation are exploited as a means to discriminate between objects in an extended scene. The purpose of this chapter is to introduce some fundamental concepts in the science of imaging polarimetry. These concepts include the Stokes-Mueller description of polarized light, the physical mechanisms that contribute to polarimetric image contrast, a mathematical description of several polarimetric imaging systems, and an example target detection algorithm. Polarimetric image contrast is discussed in terms of reflected, emitted, and scattered light. Special empha…

Optoelectronic Information Encryption with Incoherent Light

Progress in 3-D Multiperspective Display by Integral Imaging

Three-dimensional (3-D) imaging techniques have the potential to establish a future mass-market in the fields of entertainment and communications. Integral imaging (InI), which can capture and display true 3-D color images, has been seen as the right technology for 3-D viewing for audiences of more than one person. Due to the advanced degree of its development, InI technology could be ready for massive commercialization in the coming years. This development is the result of a strong research effort performed over the past few years. In this sense, this paper is devoted to reviewing some recent advances in InI, which have allowed improvement in the response of InI systems to the problems of …

Single-shot color digital holography based on the fractional Talbot effect

We present a method for recording on-axis color digital holograms in a single shot. Our system performs parallel phase-shifting interferometry by using the fractional Talbot effect for every chromatic channel simultaneously. A two-dimensional binary amplitude grating is used to generate Talbot periodic phase distributions in the reference beam. The interference patterns corresponding to the three chromatic channels are captured at once at different axial distances. In this scheme, one-shot recording and digital reconstruction allow for real-time measurement. Computer simulations and experimental results confirm the validity of our method.

Focus issue introduction: 3D image acquisition and display: technology, perception and applications.

This Feature Issue of Optics Express is organized in conjunction with the 2021 Optica (OSA) conference on 3D Image Acquisition and Display: Technology, Perception and Applications which was held virtually from 19 to 23, July 2021 as part of the Imaging and Sensing Congress 2021. This Feature Issue presents 29 articles which cover the topics and scope of the 2021 3D conference. This Introduction provides a summary of these articles.

Recent Advances in the Capture and Display of Macroscopic and Microscopic 3-D Scenes by Integral Imaging

The capture and display of images of 3-D scenes under incoherent and polychromatic illumination is currently a hot topic of research, due to its broad applications in bioimaging, industrial procedures, military and surveillance, and even in the entertainment industry. In this context, Integral Imaging (InI) is a very competitive technology due to its capacity for recording with a single exposure the spatial-angular information of light-rays emitted by the 3-D scene. From this information, it is possible to calculate and display a collection of horizontal and vertical perspectives with high depth of field. It is also possible to calculate the irradiance of the original scene at different dep…

Method to Remedy Image Degradations Due to Facet Braiding in 3D Integral-Imaging Monitors

One of the main challenges in 3D integral imaging (InI) is to overcome the limited depth of field of displayed 3D images. Although this limitation can be due to many factors, the phenomenon that produces the strongest deterioration of out-of-focus images is the facet braiding. In fact, the facet braiding is an essential problem, since InI 3D monitors are not feasible if the braiding problem is not solved. In this paper, we propose a very simple method for overcoming the facet braiding effect which is a serious limitation for realization of 3D TV based on InI. Hybrid experiments are presented to verify the theoretical analysis.

Depth rendering of large incoherent scenes from integral images

Integral imaging is a technique that provides the spatial and angular information of three-dimensional (3D) scenes through a single shot. Taking advantage of this capability, different applications have been developed. Some of these applications are the 3D display and digital post-processing, in particular depth-reconstruction from integral images.

Multidimensional Integral Imaging and Recognition in Degraded Environments

We present an overview of our work on multidimensional integral imaging systems. Integral-imaging-based multidimensional optical sensing and imaging will be described for 3-D visualization, seeing through obscurations, material inspection, augmented reality, biomedical applications, and object recognition from microscales to long-range imaging.

Single-shot digital holography
by use of the fractional Talbot effect

We present a method for recording in-line single-shot digital holograms based on the fractional Talbot effect. In our system, an image sensor records the interference between the light field scattered by the object and a properly codified parallel reference beam. A simple binary two-dimensional periodic grating is used to codify the reference beam generating a periodic three-step phase distribution over the sensor plane by fractional Talbot effect. This provides a method to perform single-shot phase-shifting interferometry at frame rates only limited by the sensor capabilities. Our technique is well adapted for dynamic wavefront sensing applications. Images of the object are digitally recon…

Free segmentation in rendered 3D images through synthetic impulse response in integral imaging

Integral Imaging is a technique that has the capability of providing not only the spatial, but also the angular information of three-dimensional (3D) scenes. Some important applications are the 3D display and digital post-processing as for example, depth-reconstruction from integral images. In this contribution we propose a new reconstruction method that takes into account the integral image and a simplified version of the impulse response function (IRF) of the integral imaging (InI) system to perform a two-dimensional (2D) deconvolution. The IRF of an InI system has a periodic structure that depends directly on the axial position of the object. Considering different periods of the IRFs we …

Guest Editorial Three-Dimensional Displays and Visualization

THREE-DIMENSIONAL (3D) imaging and display is a natural concept for humans as it is a common vision attribute of our binocular vision, perception, and brain processing. However, until recently, our experiences have been mainly limited to the technologically inferior two-dimensional (2D) as evidenced from widespread use of 2D photography, cinema, and liquid crystal or LED-display for television, computer displays, etc.

Analysis of the depth of field of integral imaging displays based on wave optics.

In this paper, we analyze the depth of field (DOF) of integral imaging displays based on wave optics. With considering the diffraction effect, we analyze the intensity distribution of light with multiple micro-lenses and derive a DOF calculation formula for integral imaging display system. We study the variations of DOF values with different system parameters. Experimental results are provided to verify the accuracy of the theoretical analysis. The analyses and experimental results presented in this paper could be beneficial for better understanding and designing of integral imaging displays.

Geometrical super resolved lensless imaging

In the field of super resolution researchers are trying to overcome both the diffraction as well as the geometrical bounds of an imaging system. In this paper we present a recently developed approach that aims to overcome the geometrical bounds while using a unified spatial light modulator (SLM) based lensless configuration.

Liquid crystal lens array for 3D microscopy and endoscope application

In this paper, we demonstrate two liquid crystal (LC) lens array devices for 3D microscope and 3D endoscope applications respectively. Compared with the previous 3D biomedical system, the proposed LC lens arrays are not only switchable between 2D and 3D modes, but also are able to adjust focus in both modes. The multi-function liquid crystal lens (MFLC-lens) array with dual layer electrode has diameter 1.42 mm, which is much smaller than the conventional 3D endoscope with double fixed lenses. The hexagonal liquid crystal micro-lens array (HLC-MLA) instead of fixed micro-lens array in 3D light field microscope can extend the effective depth of field from 60 um to 780 um. To achieve the LC le…

One-shot color digital holography based on the fractional talbot effect

We present a simple method for recording on-axis color digital holograms in a single shot. Our system performs parallel phase-shifting interferometry by using the fractional Talbot effect for every chromatic channel simultaneously. Experimental results are also shown.

Reconstruction Improvement in Integral Fourier Holography by Micro-Scanning Method

Although integral holography has many promising advantages in the field of 3D imaging, the resolution of reconstructed holographic image is still limited by the insufficient information captured. To improve the reconstruction quality, an integral Fourier holographic imaging method based on micro-scanning of the micro-lens array is proposed in this paper. The micro-scanning of the micro-lens array can increase the sampling rate in spatial frequency domain and the information of the generated Fourier hologram, which will eventually eliminate the overlapping effect in the reconstructed 3D image. Experiments for different micro-scanning modes are carried out to verify the feasibility of the pro…

Three Dimensional Sensing, Visualization, and Display

This keynote address will present an overview of recent advances in Three-dimensional (3D) sensing, imaging and display. We shall discuss both passive sensing integral imaging and active sensing computational holographic imaging for 3D visualization, display, and image recognition. Mathematical analysis, computer simulations, and optical experimental results will be presented. There are numerous applications of these technologies including medical 3D imaging, 3D visualization, 3D identification and inspection, 3D television, 3D video, 3D multimedia, interactive communication, education, entertainment, and commerce.

Combining Defocus and Photoconsistency for Depth Map Estimation in 3D Integral Imaging

This paper presents the application of a depth estimation method for scenes acquired using a Synthetic Aperture Integral Imaging (SAII) technique. SAII is an autostereoscopic technique consisting of an array of cameras that acquires images from different perspectives. The depth estimation method combines a defocus and a correspondence measure. This approach obtains consistent results and shows noticeable improvement in the depth estimation as compared to a minimum variance minimisation strategy, also tested in our scenes. Further improvements are obtained for both methods when they are fed into a regularisation approach that takes into account the depth in the spatial neighbourhood of a pix…

Advances in three-dimensional integral imaging: sensing, display, and applications [Invited]

Three-dimensional (3D) sensing and imaging technologies have been extensively researched for many applications in the fields of entertainment, medicine, robotics, manufacturing, industrial inspection, security, surveillance, and defense due to their diverse and significant benefits. Integral imaging is a passive multiperspective imaging technique, which records multiple two-dimensional images of a scene from different perspectives. Unlike holography, it can capture a scene such as outdoor events with incoherent or ambient light. Integral imaging can display a true 3D color image with full parallax and continuous viewing angles by incoherent light; thus it does not suffer from speckle degrad…

Three-dimensional display by smart pseudoscopic-to-orthoscopic conversion with tunable focus.

The original aim of the integral-imaging concept, reported by Gabriel Lippmann more than a century ago, is the capture of images of 3D scenes for their projection onto an autostereoscopic display. In this paper we report a new algorithm for the efficient generation of microimages for their direct projection onto an integral-imaging monitor. Like our previous algorithm, the smart pseudoscopic-to-orthoscopic conversion (SPOC) algorithm, this algorithm produces microimages ready to produce 3D display with full parallax. However, this new algorithm is much simpler than the previous one, produces microimages free of black pixels, and permits fixing at will, between certain limits, the reference …

Photoelastic Analysis of Partially Occluded Objects With an Integral-Imaging Polariscope

Polariscopes are the basic instruments used for the analysis of the stress state of transparent materials. Polarized light passing through a 3D object carries the integrated effect of the stress field along the light path. Therefore, conventional polariscopes are not able to discern the stress state of objects involving multiple plates with mutual occlusions. In this paper we propose a novel experimental system for three-dimensional stress analysis based on the combination of a polariscope and Synthetic Aperture Integral Imaging technique. Experimental results show the system's ability to recover the information of the stress distribution of a set of plates located at different depths havin…

Parallel phase-shifting digital holography based on the fractional Talbot effect

A method for recording on-axis single-shot digital holograms based on the self-imaging phenomenon is reported. A simple binary two-dimensional periodic amplitude is used to codify the reference beam in a Mach-Zehnder interferometer, generating a periodic three-step phase distribution with uniform irradiance over the sensor plane by fractional Talbot effect. An image sensor records only one shot of the interference between the light field scattered by the object and the codified parallel reference beam. Images of the object are digitally reconstructed from the digital hologram through the numerical evaluation of the Fresnel diffraction integral. This scheme provides an efficient way to perfo…

Lightfield recording and reconstruction by integral imaging

Integral imaging is a rising 3D imaging technique that can be considered the incoherent version of holography. In integral imaging the multiperspective information of 3D scenes is stored in a 2D picture. Such picture is nothing but a sampling version of the lightfield emitted by the 3D scene. The recorded lightfield can be used for many purposes. One is the display of 3D color scenes to audiences or much more than one person. Other is the 3D display, with full parallax, in personal monitors, like the screen of a Smartphone, a tablet, or the monitor used by a surgeon in an endoscopic operation. Other important types of applications are connected with the topographic reconstruction, slice by …

Microscopic and macroscopic 3D imaging and display by integral imaging

Integral imaging is a rising 3D imaging technique that can be considered the incoherent version of holography. In integral imaging the multiperspective information of 3D scenes is stored in a 2D picture. Such picture, composed by a set of elemental images, is obtained through a 2D array of microlenses. The elemental-images set can be used for many purposes. One is the display of 3D color scenes to audiences or much more than one person. Other is the 3D display, with full parallax, in personal monitors, like the screen of a smartphone, a tablet, or the monitor used by a surgeon in an endoscopic operation. Other important types of applications are connected with the topographic reconstruction…

Video4.avi

Fig. 15. Images corresponding to the 3D reconstruction at the depth where the hand is in focus, for three gestures: (a) Open, (b) Left, and (c) Deny gestures. STIPs were applied to the videos for this depth reconstruction. Video1 and Video2 show two different gestures, where only the hand in is focus. Video3 and Video4 show the detected STIPs. Most of them appear where the gesture is taking place.

Video1.avi

Fig. 15. Images corresponding to the 3D reconstruction at the depth where the hand is in focus, for three gestures: (a) Open, (b) Left, and (c) Deny gestures. STIPs were applied to the videos for this depth reconstruction. Video1 and Video2 show two different gestures, where only the hand in is focus. Video3 and Video4 show the detected STIPs. Most of them appear where the gesture is taking place.

Video3.avi

Fig. 15. Images corresponding to the 3D reconstruction at the depth where the hand is in focus, for three gestures: (a) Open, (b) Left, and (c) Deny gestures. STIPs were applied to the videos for this depth reconstruction. Video1 and Video2 show two different gestures, where only the hand in is focus. Video3 and Video4 show the detected STIPs. Most of them appear where the gesture is taking place.

Video1.avi

Fig. 15. Images corresponding to the 3D reconstruction at the depth where the hand is in focus, for three gestures: (a) Open, (b) Left, and (c) Deny gestures. STIPs were applied to the videos for this depth reconstruction. Video1 and Video2 show two different gestures, where only the hand in is focus. Video3 and Video4 show the detected STIPs. Most of them appear where the gesture is taking place.

Video2.avi

Fig. 15. Images corresponding to the 3D reconstruction at the depth where the hand is in focus, for three gestures: (a) Open, (b) Left, and (c) Deny gestures. STIPs were applied to the videos for this depth reconstruction. Video1 and Video2 show two different gestures, where only the hand in is focus. Video3 and Video4 show the detected STIPs. Most of them appear where the gesture is taking place.

Video4.avi

Fig. 15. Images corresponding to the 3D reconstruction at the depth where the hand is in focus, for three gestures: (a) Open, (b) Left, and (c) Deny gestures. STIPs were applied to the videos for this depth reconstruction. Video1 and Video2 show two different gestures, where only the hand in is focus. Video3 and Video4 show the detected STIPs. Most of them appear where the gesture is taking place.

Video2.avi

Fig. 15. Images corresponding to the 3D reconstruction at the depth where the hand is in focus, for three gestures: (a) Open, (b) Left, and (c) Deny gestures. STIPs were applied to the videos for this depth reconstruction. Video1 and Video2 show two different gestures, where only the hand in is focus. Video3 and Video4 show the detected STIPs. Most of them appear where the gesture is taking place.

Video3.avi

Fig. 15. Images corresponding to the 3D reconstruction at the depth where the hand is in focus, for three gestures: (a) Open, (b) Left, and (c) Deny gestures. STIPs were applied to the videos for this depth reconstruction. Video1 and Video2 show two different gestures, where only the hand in is focus. Video3 and Video4 show the detected STIPs. Most of them appear where the gesture is taking place.