Publications: 3D and 2D Imaging Systems, and Holography

3D Mueller

Estimation of Degree of Polarization in Low Light Using Truncated Poisson Distribution

Marcos Aviñoá, Xin Shen, Salvador Bosch, Bahram Javidi, Artur Carnicer

IEEE Photonics Journal 14(3), 6531908 (2022)

The Degree of Polarization (DoP) of a light beam inside a medium contains unique information about the medium. 3D imaging techniques constitute an optimal procedure for determining the DoP under low light conditions, as the computational reconstruction process can increase the signal-to-noise ratio of the detected light. The definition of the DoP contains a division by the total number of detected photons from the sensor. However, under photon starved conditions, the number of detected photons at a single time period may be equal to zero. This may pose a division by zero problem for the computation of DoP. In this work, we consider a truncated Poisson distribution to overcome this problem and show that the mean value of the computed DoP goes to zero independently of the state of polarization of the light. The validity of our approach is verified by capturing the light fields of a test object to compute its DoP under low light conditions. The formulae derived in this work can be used to correct the deviation of the mean value of the DoP with respect to the ideal measurements.

Roadmap on digital holography [Invited]

Bahram Javidi, Artur Carnicer, Arun Anand, George Barbastathis, Wen Chen, Pietro Ferraro, J. W. Goodman, Ryoichi Horisaki, Kedar Khare, Malgorzata Kujawinska, Rainer A. Leitgeb, Pierre Marquet, Takanori Nomura, Aydogan Ozcan, YongKeun Park, Giancarlo Pedrini, Pascal Picart, Joseph Rosen, Genaro Saavedra, Natan T. Shaked, Adrian Stern, Enrique Tajahuerce, Lei Tian, Gordon Wetzstein, and Masahiro Yamaguchi

Optics Express 29, 35078-35118 (2021)

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.

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

Bahram Javidi, Artur Carnicer, Jun Arai, Toshiaki Fujii, Hong Hua, Hongen Liao, Manuel Martínez-Corral, Filiberto Pla, Adrian Stern, Laura Waller, Qiong-Hua Wang, Gordon Wetzstein, Masahiro Yamaguchi, Hirotsugu Yamamoto

Optics Express 28(22) 32266-32293 (2020)

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.

Three-dimensional polarimetric integral imaging in photon-starved conditions: performance comparison between visible and long wave infrared imaging

Kashif Usmani, Timothy O'Connor, Xin Shen, Pete Marasco, Artur Carnicer, Dipak Dey, Bahram Javidi

Optics Express 28(13) 19281-19294 (2020)

Three-dimensional (3D) polarimetric integral imaging (InIm) to extract the 3D polarimetric information of objects in photon-starved conditions is investigated using a low noise visible range camera and a long wave infrared (LWIR) range camera, and the performance between the two sensors is compared. Stokes polarization parameters and degree of polarization (DoP) are calculated to extract the polarimetric information of the 3D scene while integral imaging reconstruction provides depth information and improves the performance of low-light imaging tasks. An LWIR wire grid polarizer and a linear polarizer film are used as polarimetric objects for the LWIR range and visible range cameras, respectively. To account for a limited number of photons per pixel using the visible range camera in low light conditions, we apply a mathematical restoration model at each elemental image of visible camera to enhance the signal. We show that the low noise visible range camera may outperform the LWIR camera in detection of polarimetric objects under low illumination conditions. Our experiments indicate that for 3D polarimetric measurements under photon-starved conditions, visible range sensing may produce a signal-to-noise ratio (SNR) that is not lower than the LWIR range sensing. We derive the probability density function (PDF) of the 2D and 3D degree of polarization (DoP) images and show that the theoretical model demonstrates agreement to that of the experimentally obtained results. To the best of our knowledge, this is the first report comparing the polarimetric imaging performance between visible range and infrared (IR) range sensors under photon-starved conditions and the relevant statistical models of 3D polarimetric integral imaging.

Three-dimensional polarimetric integral imaging under low illumination conditions

Xin Shen, Artur Carnicer, Bahram Javidi

Optics Letters 44(11), 3230-3233 (2019)

Conventional polarimetric imaging may perform poorly in photon-starved environments. In this Letter, we demonstrate the potential of integral imaging and dedicated algorithms for extracting three-dimensional (3D) polarimetric information in low light, and reducing the effects of measurement uncertainty. In our approach, the Stokes polarization parameters are measured and statistically analyzed in low illumination conditions through 3D-reconstructed polarimetric images with dedicated algorithms to improve the signal-to-noise ratio (SNR). The 3D volumetric degree of polarization (DoP) of the scene is calculated by statistical algorithms. We show that the 3D polarimetric information of the object can be statistically extracted from the Stokes parameters and 3D DoP images. Experimental results along with a novel statistical analysis verify the feasibility of the proposed approach for polarimetric 3D imaging in photon-starved environments and show that it outperforms its two-dimensional counterpart in terms of SNR. To the best of our knowledge, this is the first report of novel optical experiments along with novel statistical analysis and dedicated algorithms to recover 3D polarimetric imaging signatures in low light.

Mueller matrix polarimetry with 3D integral imaging

Artur Carnicer, Salvador Bosch, Bahram Javidi

Optics Express 27(8) 11525-11536 (2019)

In this paper, we introduce the Mueller matrix imaging concepts for 3D Integral Imaging Polarimetry. The Mueller matrix of a complex scene is measured and estimated with 3D integral imaging. This information can be used to analyze the complex polarimetric behavior of any 3D scene. In particular, we show that the degree of polarization can be estimated at any selected plane for any arbitrary synthetic illumination source which may be difficult to produce in practice. This tool might open new perspectives for polarimetric analysis in the 3D domain. Also, we illustrate that 2D polarimetric images are noisier than 3D reconstructed polarimetric integral imaging. To the best of our knowledge, this is the first report on Mueller matrix polarimetry in 3D Integral Imaging.

Polarimetric 3D integral imaging in photon-starved conditions

Artur Carnicer, Bahram Javidi

Optics Express 23(5), 6408-6417 (2015)

We develop a method for obtaining 3D polarimetric integral images from elemental images recorded in low light illumination conditions. Since photon-counting images are very sparse, calculation of the Stokes parameters and the degree of polarization should be handled carefully. In our approach, polarimetric 3D integral images are generated using the Maximum Likelihood Estimation and subsequently reconstructed by means of a Total Variation Denoising filter. In this way, polarimetric results are comparable to those obtained in conventional illumination conditions. We also show that polarimetric information retrieved from photon starved images can be used in 3D object recognition problems. To the best of our knowledge, this is the first report on 3D polarimetric photon counting integral imaging.

Design and implementation of a scene-dependent dynamically selfadaptable wavefront coding imaging system

Guillem Carles, Carme Ferran, Artur Carnicer, Salvador Bosch

Computer Physics Communications 183 (1), 147-154 (2011)

A computational imaging system based on wavefront coding is presented. Wavefront coding provides an extension of the depth-of-field at the expense of a slight reduction of image quality. This trade-off results from the amount of coding used. By using spatial light modulators, a flexible coding is achieved which permits it to be increased or decreased as needed. In this paper a computational method is proposed for evaluating the output of a wavefront coding imaging system equipped with a spatial light modulator, with the aim of thus making it possible to implement the most suitable coding strength for a given scene. This is achieved in an unsupervised manner, thus the whole system acts as a dynamically selfadaptable imaging system. The program presented here controls the spatial light modulator and the camera, and also processes the images in a synchronised way in order to implement the dynamic system in real time. A prototype of the system was implemented in the laboratory and illustrative examples of the performance are reported in this paper.

Phase mask selection in wavefront coding systems: A design approach

Guillem Carles, Artur Carnicer, Salvador Bosch

Optics and Lasers in Engineering 48(7), 779-785 (2010)

A method for optimizing the strength of a parametric phase mask for a wavefront coding imaging system is presented. The method is based on an optimization process that minimizes a proposed merit function. The goal is to achieve modulation transfer function invariance while quantitatively maintaining final image fidelity. A parametric filter that copes with the noise present in the captured images is used to obtain the final images, and this filter is optimized. The whole process results in optimum phase mask strength and optimal parameters for the restoration filter. The results for a particular optical system are presented and tested experimentally in the laboratory. The experimental results show good agreement with the simulations, indicating that the procedure is useful.

Wavefront reconstruction by adding modulation capabilities of two liquid crystal devices

Raul Tudela, Estela Martın, Ignasi Labastida, Santiago Vallmitjana, Artur Carnicer

Optical Engineering 43(11) 2650-2657 (2004)

We analyze the behavior of complex information in the Fresnel domain, taking into account the limited capability to display complex values of liquid crystal devices when they are used as holographic displays. To do this analysis we study the reconstruction of Fresnel holograms at several distances using the different parts of the complex distribution. We also use the information adjusted with a method that combines two configurations of the devices in an adding architecture. The results of the error analysis show different behavior for the reconstructions when using the different methods. Simulated and experimental results are presented.

Full complex Fresnel holograms displayed on liquid crystal devices

Raul Tudela, Estela Martin-Badosa, I Labastida, S Vallmitjana, I Juvells, A Carnicer

Journal of Optics A: Pure and Applied Optics 5, S189 (2003)

We propose a method to display full complex Fresnel holograms by adding the information displayed on two analogue ferroelectric liquid crystal spatial light modulators. One of them works in real-only configuration and the other in imaginary-only mode. The Fresnel holograms are computed by backpropagating an object at a selected distance with the Fresnel transform. Then, displaying the real and imaginary parts on each panel, the object is reconstructed at that distance from the modulators by simple propagation of light. We present simulation results taking into account the specifications of the modulators as well as optical results. We have also studied the quality of reconstructions using only real, imaginary, amplitude or phase information. Although the real and imaginary reconstructions look acceptable for certain distances, full complex reconstruction is always better and is required when arbitrary distances are used.

A simple method for displaying Fresnel holograms on liquid crystal panels

Raul Tudela, Ignasi Labastida, E Martın-Badosa, Santiago Vallmitjana, Ignacio Juvells, Artur Carnicer

Optics communications 214(1-6) 107-114 (2002)

In this paper we present a method for reconstructing Fresnel holograms using two liquid crystal devices, one to display the amplitude information and the other to display the phase. The theoretical approach has been adapted to real configurations of VGA panels removed from a commercial video projector. The optical setup is based on the projection of the phase plane into the amplitude plane by means of an imaging lens. Simulated and experimental results are presented.