Holographic Recording System Research Articles

Single-exposure multi-wavelength optical diffraction tomography based on space-angle dual multiplexing holography.

We present a space-angle dual multiplexing holographic recording system for realizing single-exposure multi-wavelength optical diffraction tomographic (ODT) imaging. This system is achieved by combining the principle of single-exposure multi-wavelength holographic imaging technique based on angle-division multiplexing with the principle of single-exposure ODT imaging technique based on microlens array multi-angle illuminations and space-division multiplexing. Compared with the existing multi-wavelength ODT imaging methods, it enables the holographic recording of all the diffraction tomography information of a measured specimen at multiple illumination wavelengths in a single camera exposure without any scan mechanism. Using our proposed data processing method, the multi-wavelength three-dimensional (3D) refractive index tomograms of a specimen can be eventually reconstructed from single recorded multiplexing hologram. Experimental results of a static polystyrene bead and a living C. elegans worm demonstrate the feasibility of this system.

Fractional Fourier-transform off-axis digital holographic imaging

A fractional Fourier-transform digital holographic imaging method with resolution enhancement features is presented. In an optical configuration, an extended fractional Fourier-transform optical setup is set in the object arm of an off-axis digital holographic recording system to record a fractional Fourier-transform hologram via the optical interference of the fractional Fourier-transform wavefront of an object wave with a reference wave. For reconstruction imaging, the reconstruction approach for fractional Fourier-transform holograms is given. In the experiment, the fractional Fourier-transform digital holograms are recorded under the different recording parameters, and their amplitude images are effectively reconstructed. The imaging results demonstrate that the reconstruction-imaging resolution of fractional-order Fourier-transform holograms is obviously enhanced compared to that of conventional image-plane holograms. The presented fractional Fourier-transform digital holographic imaging with resolution enhancement and optical configuration flexibility provides, to our knowledge, a novel way for off-axis digital holographic imaging.

Geometric-Optical Model of Digital Holographic Particle Recording System and Features of Its Application

The paper proposes an equivalent optical scheme of an in-line digital holographic system for particle recording and a mathematical model that establishes a one-to-one correspondence between the dimensional and spatial parameters of a digital holographic image of a particle and the imaged particle itself. The values of the model coefficients used to determine the real size and longitudinal coordinate of a particle according to its holographic image are found by calibration. The model was tested in field and laboratory conditions to calibrate a submersible digital holographic camera designed to study plankton in its habitat. It was shown that four calibration measurements are sufficient enough to determine the model coefficients, and the developed design of the submersible digital holographic camera makes it possible to perform these measurements during the recording of each hologram. In addition, this neither requires data on the refractive index of the medium with particles nor on the parameters of the optical elements of the scheme. The paper presents the results of marine experiments in the Kara Sea and the Laptev Sea, as well as in fresh water in laboratory conditions and in Lake Baikal. The error in measuring the particle size in seawater without the use of the model is 53.8%, while the error in determining their longitudinal coordinates is 79.3%. In fresh water, the same errors were 59% and 54.5%, respectively. The error in determining the position of a particle with the use of the designed mathematical model does not exceed 1.5%, and the error in determining the size is 4.8%. The model is sensitive to changes in the optical properties of the medium, so it is necessary to perform calibration in each water area, and one calibration is quite sufficient within the same water area. At the same time, the developed design of the submersible holographic camera allows, if necessary, calibration at each holographing of the medium volume with particles.

Self-stabilized holographic interferometry for the measurement of two-dimensional vibrations

In this paper, we focus on the features of a self-stabilized holographic recording system with a photorefractive crystal as a vibration optical sensor. With it and the time-average holographic interferometry technique, high quality vibration maps of a thin plate were obtained. The results show that the system is capable of phase control in low diffraction efficiency conditions and under high disturbances.

Phase-based reconstruction optimization method for digital holographic measurement of microstructures.

Digital holography has transformative potential in measuring stacked-chip microstructures due to its noninvasive, single-shot, full-field characteristics. However, uncertainties in reconstruction distance inevitably lead to resolving blur and reconstruction distortion. Herein, we propose a phase-based reconstruction optimization method that consists of a phase-evaluation function and a structured surface-characterization model. Our proposed method involves setting a reconstruction distance range, obtaining phase information using sliced numerical reconstruction, and optimizing the reconstruction distance by finding the extreme value of the function, which identifies the focal plane of the reconstructed image. The structure of the surface topography is then characterized using the characterization model. We perform simulations of the recording, reconstruction, and characterization to verify the effectiveness of the proposed method. To further demonstrate the approach, a simple holographic recording system is constructed to measure a standard resolution target, and the measurement results are compared with a commercial instrument. The simulation and experiment demonstrate, respectively, 31.16% and 34.41% improvement in step-height characterization accuracy.

Real-time noise-free inline self-interference incoherent digital holography with temporal geometric phase multiplexing

In this paper, we propose a real-time incoherent digital holographic (IDH) recording system free from bias and twin-image noises. A motionless three-step polarization-encoded phase-shifter operating at 99 Hz is realized with two electrically controllable birefringence-mode liquid crystal cells operating in tandem with a geometric phase lens and polarizers. Based on the proposed optical configuration, a coaxial straight-line self-interference IDH recording system is devised. Notably, the elimination of bias and twin-image noise from three phase-shifted images is demonstrated as a proof of concept. Moreover, complex-valued holographic video acquisitions with a resolution greater than 20 megapixels are demonstrated, with an effective acquisition frequency of 33 Hz.

Photodetecting properties on Sn-doped Bi2S3 thin film fabricated by nebulizer spray pyrolysis technique

Metal chalcogenides have recently gained intensive attention due to their tunable bandgap energy, optoelectronic characteristics, and exceptional optical absorption. Because of the potential advantage of photodetectors, photovoltaic, holographic recording systems, and field-effect transistors, bismuth tri-sulfide (Bi2S3) crystals, in particular, have attracted a lot of focus in scientific research. In this study, the low-cost nebulizer spray technique was employed to synthesize the proposed Bi2S3:Sn thin films on glass substrates, varying the Sn doping concentrations in Bi2S3 films (from 1 to 3%). The crystallites of the orthorhombic-structured polycrystalline Bi2S3 films were all oriented in the same direction (130). According to the XRD spectra, preferred orientation and crystalline quality were improved by Sn doping concentrations up to 2%, but, above 2% of the Sn doping ratio, the structural properties were decreased. With increasing Sn-doping levels, the estimated direct band gap (Eg) of the Bi2S3:Sn films decreased, reaching a low value of 2.01 eV at 2% Sn and then rising. A field emission scanning electron microscope (FESEM) was applied to determine the size and shape of the grains in prepared Sn: Bi2S3 films.The 2% Sn-doped Bi2S3 thin film may be more appropriate for high-speed optoelectronic devices due to its high responsivity (1.24 AW−1), external quantum efficiency (40%), and detectivity properties (1.83 × 1010Jones). A potential mechanism for photodetector performance in the presence of air and UV radiation was also discussed in the present work for the proposed Sn: Bi2S3 thin films.

Noticeable photo-sensing properties of SnS:Cu thin films fabricated by thermal evaporation technique

Due to their optoelectronic behavior, superior optical absorption, and tunable band-gap energies, metal chalcogenides have attracted global attention in recent decades. SnS (tin sulfide) crystals, in particular, have drawn a lot of interest because of their prospective applications in photovoltaics, photo-detectors, field-effect transistors, and holographic recording systems. Thermal evaporation technique was employed to develop the SnS:Cu thin films on glass substrates by varying 1 to 4 wt% of the Cu doping concentration. XRD, Raman, FESEM, UV–Vis/NIR Spectrometer, and photo-sensing measurement System were used to analyze the films structural, optical, and electrical properties. The films exhibit a polycrystalline morphology of orthorhombic SnS structure with the crystalline structure orientated in the same direction along the (111) plane. The XRD spectra demonstrated that Cu doping concentrations up to 2% improve preferential orientation and crystalline quality, whereas the increase in Cu dopant concentration above 2% affects the orientation of the peaks and quality of the crystals. The estimated direct bandgap Eg of the SnS:Cu films falls with increasing Cu-doping concentration, reaches a low value of 1.53 eV with 2% Cu, and thereafter increases. Scanning electron microscopy was used to evaluate the surface morphology, and average grain size of SnS:Cu thin films (SEM). Due to their high Responsivity (2.92 × 10−2 AW−1), External quantum efficiency (6.8%), and Detectivity (1.20 × 109 Jones) characteristics, the 2% Cu doped SnS film may be better suitable for photosensor devices.

Lightguide type Maxwellian near-eye display with enlarged horizontal field of view by optical reconfiguration of input image

We present a novel design of the lightguide type optical see-through Maxwellian near-eye display. The proposed display reconfigures vertically long input images to horizontally long output images for wide horizontal viewing-angle. The reconfiguration of the input images is optically performed by using folding holographic optical elements and different numbers of total internal reflections within the lightguide. The upper and lower parts of the in-coupled image undergo different numbers of total internal reflections, being separated into two images. After the separation, the upper part is additionally diffracted by the folding holographic optical element to the side of the lower part. Finally, the horizontally tiled upper and lower parts are out-coupled towards the eye by corresponding holographic optical elements. The optical power of the output couplers converges the output image to a focal spot on the eye pupil so that users experience all-in-focus images. In the optical experiment, the wavelength difference between the display and the holographic optical element recording system was pre-compensated by adjusting the recording angle. Our prototype successfully demonstrates horizontal tiling of the upper and lower parts of the input images, showing a two-times larger output horizontal field of view than the input.

Versatile approach to laser beam shaping and analyzing by holographic phase masks

A new technology that includes a flexible holographic recording system using photo-thermo-refractive (PTR) glass is demonstrated for creating so-called ‘holographic phase masks’ or HPMs. These diffractive optical elements are permanently recorded in the PTR glass, can be multiplexed as with normal holograms, do not require electric power to operate, and can perform near arbitrary beam phase transformations. The holographic setup includes a spatial light modulator that enables recording transmitting volume Bragg gratings (VBGs) with arbitrary phase patterns encoded into them. As a result, the desirable phase pattern is introduced in a beam that is diffracted by the VBG. These HPMs are tunable within the visible and near IR spectral regions and can be made achromatic, with spectral widths of up to 50 nm. Furthermore, they tolerate laser power densities on the order of several kW cm−2. Applications of HPMs include high-power, broadband laser beam shaping and modal analysis of complex beams profiles, both of which are demonstrated here.

Michelson-interferometric-configuration-based incoherent digital holography with a geometric phase shifter

The phase-shifting method is a simple and efficient approach to extract complex hologram information free of bias and twin-image noise. In this study, the geometric phase-shifting method is utilized for a self-interference incoherent digital holographic recording system based on the Michelson-type interferometer. The phase-shifting module consists of a horizontal polarizer, and two achromatic quarter-wave plates are employed inside the interferometer, replacing conventional phase-shifting devices, such as the piezo-actuated mirror. Since the phase-shifting amount of the introduced method herein is theoretical, regardless of the input wavelength, the simultaneous recording of step-wise phase-shifted interferograms for different color channels is available. Therefore, the multi-color hologram recording is achieved with fewer numbers of exposures. The demonstration of multi-color hologram recording and reconstruction are presented to validate the proposed idea.

Single-shot Fresnel incoherent digital holography based on geometric phase lens

ABSTRACTSingle-shot and incoherent imaging are two important properties of digital holography that can extend its application range. In this study, a simple, compact, in-line Fresnel incoherent digital holographic recording system is proposed that is capable of single-shot and three-dimensional imaging. A geometric phase lens is used as the common-path beam splitter based on its special wave separation property. Parallel phase-shifting holography is used to achieve single-shot operation with the use of a polarization imaging camera together with space-division multiplexing. The capabilities of the proposed technique are experimentally confirmed by imaging two standard test charts based on a compact setup.

Serialized holography for brand protection and authentication.

The problems presented by counterfeit products and documentation are discussed. Limitations of existing holograms for anti-counterfeit applications are described. We describe the advantages of full holographic serialization and the requirements in terms of materials and techniques for mass production of true serialized holograms. These requirements having been met, we report for the first time the mass production of fully serialized holograms. The novelty of the approach consists of the direct use of the product manufacturer's information as the object in a holographic recording system along with a self-processing photopolymer and modular optical system to facilitate mass production of truly serialized volume holograms. Various types of serialized holograms for overt and covert authentication are described. We discuss briefly the application of Optrace's manufacturing methods for future generation holographic devices.

Achromatic phase shifting self-interference incoherent digital holography using linear polarizer and geometric phase lens.

A simple Fresnel-type self-interference incoherent digital holographic recording system is proposed. The main part of the system consists of the two linear polarizers and geometric phase lens. The geometric phase lens is employed as a polarization selective common-path interferometer. One of the polarizers is rotated by the motor and serves as a phase-shifter with the geometric phase lens, to eliminate the bias and twin image noise. A topological phase is obtained by the relative angle between the polarizer and geometric phase lens. Since this phase shifting method does not depend on the change of the optical path length, the phase shifting performance is almost constant in the broad spectral range. Using the proposed achromatic phase shifting method, a simultaneous three-color phase shifting digital hologram recording under the incoherent light source is demonstrated.

Coherence experiments in single-pixel digital holography

In optical scanning holography (OSH), the coherence properties of the acquired holograms depend on the single-pixel size, i.e., the active area of the photodetector. For the first time, to the best of our knowledge, we have demonstrated coherent, partial coherent, and incoherent three-dimensional (3D) imaging by experiment in such a single-pixel digital holographic recording system. We have found, for the incoherent mode of OSH, in which the detector of the largest active area is applied, the 3D location of a diffusely reflecting object can be successfully retrieved without speckle noise. For the partial coherent mode employing a smaller pixel size of the detector, significant speckles and randomly distributed bright spots appear among the reconstructed images. For the coherent mode of OSH when the size of the pixel is vanishingly small, the bright spots disappear. However, the speckle remains and the signal-to-noise ratio is low.

Paper No P4: The Development of the Integrated Holographic Recording Head for Synthesized 3D Hologram Recording

AbstractAn integration of several total internal reflection (TIR) holographic optical elements (HOEs) for the design of compact holographic recording system is discussed. Methods of waveguide holography (WGH) permits to realize the concept of pure HOE recording setup for synthesizing three‐dimensional (3D) holograms. So the idea of homogeneous technology for “HOLOGRAMS BREEDING” was approved. The several schemes for light guiding HOE recording was proposed to obtain integrated TIR illumination and reference beam forming units. In this paper, it is shown that the specific light transformation waveguide holograms permit to construct efficient recording setup for 3D synthesized micro‐hogel recording. It is also shown several experimental schemes of reflection/transmition variants of 3D synthesized hologram recording. The schemes of HOE operation improvement are discussed and some experimental results are shown.

A hogel-based holographic recording system and its hologram reconstruction improvement

This paper presents a holographic pixel (hogel)-based recording system and its hologram reconstruction improvement for three-dimensional (3D) displays. In this system, both a ground glass and a beam expander are utilized to expand an object beam in order to reduce the discontinuities in the reconstructed images. Moreover, a digital mirror device (DMD) instead of a liquid crystal display (LCD) is used as a space light modulator (SLM) to display the encoding images with information about hogels. The pixel period and resolution of the DMD panel are 12μm and 1024ÿ768 grids, respectively. With computer controlled movement of a holographic plate, a synthetic hologram constituted of thousands of hogels with a sub-millimeter resolution (0.8mm) is recorded hogel by hogel on the holographic plate of 200mmÿ140mm in size. Experimental holographic reconstructions of synthetic holograms prove the feasibility of the proposed method by using a self-generated plane model with a resolution of 225ÿ150 pixels.

Characterization of SnSePb0.1 Thin Films Deposited by Flash Evaporation Technique

Tin Selenide compounds have attracted considerable attention because of their important properties useful for optoelectronics, holographic recording systems, electronic switching and infrared production and detection. Moreover, SnSe is a semiconductor with a band gap of about 1 eV that makes it potential candidate for solar cell material. Further, the optoelectronic properties of SnSe can be modified using doping of lead, copper etc. In this context, we report here results of the preparation and characterization of flash evaporated lead doped SnSe thin films. Thin films of SnSePb0.1having thickness of 100nm and 500nm were deposited on to chemically cleaned glass substrates. The chemical composition of the deposited SnSePb0.1thin films has been evaluated using EDAX technique. The structure of SnSePb0.1was studied using low angle XRD and it shows that the deposited films are polycrystalline in nature having orthorhombic structure. Various lattice parameters along with micro strain for both 100nm and 500nm thin films have been evaluated. Electrical transport properties have been also investigated using high temperature Hall Effect measurement in the temperature range 300 400K. The decrease in the resistivity of deposited films with increasing temperature confirms the semiconducting behavior of SnSePb0.1thin films.

Simplified sampling models for digital hologram

There are two sampling models of digital hologram in digital holographic research. The complex mathematical operation is involved in these two models, thereby leading to different results frequently and inconvenient theoretical analysis and practical application. Based on the analysis of physical processes in recording digital hologram and the study on geometry structure of CCD detector, the two sampling models are simplified into the same mathematical expression in this paper. Through studying the simplified model with cosine series expansion of digital hologram and sampling theorem, it is shown that the model has clear physical meanings and can be used for application study conveniently. Using the simplified model, we study digital holographic recording system with optical system and exact wavefront reconstruction expression verified in experiment.

High-quality digital image-plane micro-holographic system with the same wavefront curvature of reference and object wave

The digital image-plane holographic microscopy which has the same curvature radius in the object light path and the reference light path is studied for the first time to our knowledge. The configuration of this setup is analyzed and built. The point spread function of this system is derived. The factors corresponding to the imaging resolution and the imaging characteristics of this system are analyzed. The method to correct the linear phase distortion in the reconstructed optical field is discussed. The results show that this system has the largest information content, and the imaging resolution of the system is dependent on the numerical aperture of the microscope objective (MO) and on the CCD pixel size, but independent of the photosensitive surface size of the CCD. All frequency components of each point in the object wave which has passed through the MO can completely be recorded and reconstructed. And the size of illuminated region of object has no influence on the recording condition and the quality of the reconstructed image. The digital image-plane holographic microscopy with the same curvature radius in the object light path and the reference light path is an optimized holographic recording system, which can achieve high-quality imaging. The experimental results demonstrate the correctness of the theoretical analysis.