Nazif Demoli

Institute of Physics

In this study, we present an analysis of deflections in a Morpho butterfly wing using digital holographic interferometry (DHI). Our methodology revolves around an off-axis lensless Fourier holographic setup, using laser excitation to induce deflections in the object. The implementation of a DHI setup, tailored for rapid monitoring of micro-deformat...

The retrieval of the phase with single-photon states is a fundamentally and technically challenging endeavor. Here we report an experimental realization of hologram recordings with heralded single-photon illumination and continuous observation of photon statistics. Thereby, we demonstrate the basic principle of holography with single-photon states...

The retrieval of the phase with single-photon states is a fundamental and technical challenging endeavor. Here we report the first experimental realization of quantum hologram recordings with single-photon illumination and continuous observation of photon statistics before and after a basic interferometer. Thereby, we demonstrate the basic principl...

In the image plane configurations frequently used in digital holographic microscopy (DHM) systems, interference patterns are captured by a photo-sensitive array detector located at the image plane of an input object. The object information in these patterns is localized and thus extremely sensitive to phase errors caused by nonlinear hologram recor...

We introduce holographic concept based on heralded single photons. The developed quantum approach can extract holographic information even in situations when classical approach fails to detect the information.

The aim of this study was to quantify vibrations and their influence on visual acuity. The study consisted of two parts, laboratory and clinical. Time-averaged holographic interferometry (TAHI) method was used in laboratory for measuring the amplitude of tooth vibrations induced by dental handpiece. The amplitudes of tooth vibrations were measured...

Standard utilization of LCOS microdisplays in digital holography has been focused mostly on displaying holograms that are either optically recorded or numerically designed. Here we introduce a new application scope based on mapping of the object height to the phase modulation values of the LCOS. The phase of the incident light planar wave front is...

Objective This study evaluated the effects of curing modes on surface microhardness of visible light-cured resin-modified glass ionomer cements (VLC RMGIC) and a giomer after different storage periods in comparison to auto-cured resin-modified glass ionomer cements (AC RMGIC). Materials and Methods The following materials were used: VLC RMIC: Fuji...

Objectives: The aim of this study was to evaluate dimensional changes of conventional glass ionomer cements, resin-modified glass-ionomer cement, and a giomer during the setting time using digital laser interferometry. Additionally, the influence of different curing modes (“high”, “soft”, and “low”) of a light-emitting diode (LED) curing unit on di...

Vibrating diaphragms have become an important component of acoustics technology, with nearly all commercial microphones and speakers of the past half a century relying on diaphragm vibration. Although few select materials (such as nickel and boPET) are predominantly used because of their favorable properties such as small mass density and large ten...

Foil – like materials became almost unavoidable in industrial technology. Their applications are numerous, starting from protective and adhesive layers, chemical filters to electronic or optoelectronic components. Graphene oxide paper, as one of the most recent foil – like materials is made by assembly of individual graphene – oxide sheets. Its pro...

In time-averaged digital holography (TADH), one records a hologram of a periodically oscillating object by using the exposure time typically much longer than the oscillating period. Problems arise when the total available exposure time is restricted or when the oscillation period is unknown. In this work we investigate effects of short exposure tim...

Aim To determine if the addition of inert fillers to a bioactive dental restorative composite material affects its degree of conversion (DC), polymerization shrinkage (PS), and microhardness (HV). Methods Three amorphous calcium phosphate (ACP)-based composite resins: without added fillers (0-ACP), with 10% of barium-glass fillers (Ba-ACP), and wi...

Digital holography uses electronic sensors for hologram recording and numerical method for hologram reconstruction enabling thus the development of advanced holography applications. However, in some cases, the useful information is concealed in a very wide dynamic range of illumination intensities and successful recording requires an appropriate dy...

Photon-counting can serve as an useful tool in future development of the time-averaged holography technique. This paper describes briefly how several adverse conditions for recording holograms can be successfully overcome by applying advantages of photon-counting detectors.

Time-averaged holography has been using photo-emulsions (early stage) and digital photo-sensitive arrays (later) to record holograms. We extend the recording possibilities by utilizing a photon-counting camera, and we further investigate the possibility of obtaining accurate hologram reconstructions in rather severe experimental conditions. To achi...

Objective: The aim of this study was to evaluate the impact of different polymerization programs on surface microhardness of two resin-modified glass ionomer cements after different storage periods Method: Microhardness measurements were performed using a Vickers test. 5g and 10g loads were applied for 10s in Leitz Miniload2 Microhardness Tester...

Recording of digital holograms of a weak signal [0.44 counts per second (cps)] hidden below the detector’s noise (21 cps) is investigated by employing the high dynamic range of a photon-counting detector. Recording conditions are discussed in terms of the most important holographic measures, namely, the fringe visibility (or contrast) and signal-to...

The aim of this study was to (i) obtain the force-related interferometric patterns of loaded dental implant-abutment assemblies differing in diameter and brand using digital holographic interferometry (DHI) and (ii) determine the influence of implant diameter on the extent of load-induced implant deformation by quantifying and comparing the obtaine...

Objective: One of the most challenging problems regarding composite resins (CR) is their polymerization shrinkage (PS) induced by photo-polymerization. The aim of the study was to develop a new method for a more reliable and accurate measurement of PS of flowable CR (FCR). We implemented the novel sample holder into the interferometry setup, to ena...

Use of optical fiber bundles (OFBs) in digital image plane holography systems is limited due to, first, poor quality of transmitted images through the OFB and, second, further image degradation caused by overlappings in the image (also hologram) plane. Existing systems are aimed at near-distant (order of a centimeter) objects and use demanding proc...

Dental composite resins (CRs) are commonly used materials for the replacement of hard dental tissues. Degree of conversion (DC) of CR measures the amount of the un-polymerized monomers in CR, which can cause adverse biological reactions and weakening of the mechanical properties. In the past, studies have determined the positive correlation of DC v...

In relatively recent paleographic studies, a new type of the Glagolitic script, namely triangular type, was introduced as being older than the rounded type (commonly considered as the oldest known type) with possible mixing of letter types in the early period of Glagolitic writing. That hypothesis, drawn from the so-called generative model, has bee...

The purpose of this paper is to present the current activities of a research collaborative program between three institutions from Zagreb (School of Dental Medicine, Institute of Physics, and Institute Ruđer Bošković). Within the scope of this program, it is planned to investigate and find guidelines for the refinement of the properties of dental b...

Objectives: Since root canal represents a worst scenario for cementation, evaluation of stress in the root canal after adhesive cementation of different size composite posts is of great interest. Methods: In this study 35 teeth were used. FRC Postec Plus posts (Ivoclar Vivadent, Schaan, Liechtenstein) sizes 1 and 3 were cemented with Multilin...

Objectives: Evaluation of microhardness is usually related to filler content of composite-resin materials (CRM) and indicates wear resistance. The aim was to determine the difference of microhardnes between several CRM. Methods: The Vickers test was performed to measure hardness of CRM: Tetric EvoCeram (TEC), Filtek Supreme Enamel (FSE), Gradia D...

Objectives: The aim of this study was to evaluate the linear dimensional changes of conventional glass ionomer cements during setting time period. Methods: Digital laser interferometry method was used to measure linear changes during setting of Ketac Molar Aplicap (KM) (Espe), Ketac Molar Quick Aplicap (KMQ) (Espe), Fuji IX Extra (FIXE) (GC) and...

Objectives: Polymerization shrinkage and its accompanying polymerization stress maintain continuous interest in resin composite science mainly due to emerging new dental materials. The purpose of this study was to evaluate dimensional changes of 13 methacrylate/silorane–based composite materials. Methods: Linear polymerization shrinkage of 12 dif...

A real-time system is developed that employs a CCD sensor for recording and a reflective high-resolution liquid crystal display for reconstructing of image plane digital holograms. Two types of light sources, namely, the coherent (laser) and white light (LED) are used for optical reconstructions of static and dynamic object wave fronts. As expected...

Composite resin materials shrink during polymerization regardless of curing unit or polymerization program used. However, different polymerization programs lead to different shrinkage percentages. The aim of this study was to evaluate linear polymerization shrinkage for five composite materials polymerized with curing modes of two LED curing units....

Acceptable signal recovery of the band-pass signals typically used in the off-axis digital holography systems is possible in the undersampling conditions. A typical system is considered in which the angle between two beams represents a variable parameter. For the given signal bandwidth and experimental conditions the hologram reconstruction is cons...

When using the interferometric techniques, the optical path changes induce the wavefront deformations that in turn cause the appearance of fringes. One general characteristic of such an approach is the measurement sensitivity. The actual sensitivity of a holographic interferometer is a function of, on one hand, the parameters of the measuring syste...

In digital holography, primary holographic fringes are recorded using a matricial CCD sensor. Because of the low spatial resolution of currently available CCD arrays, the angle between the reference and object beams must be limited to a few degrees. Namely, due to the digitization involved, the Shannon's criterion imposes that the Nyquist sampling...

Image moments analysis is a very useful tool which allows image description invariant to translation and rotation, scale change and some types of image distortions. The aim of this work was development of simple method for fast and reliable classification of characters by using Hu's and affine moment invariants. Measure of Eucleidean distance was u...

Corona discharges are generally characterized by a low optical density whose detection is often near or under the limits of interferometric techniques. In this paper, we propose a method of digital holographic interferometry that enables detection with enhanced sensitivity. This sensitivity increase is obtained by post-processing the digital hologr...

Clinical Relevance Holographic interferometry offers precise insight into both the frequency and location of cohesive fractures through its fringe information. If flowable composites are not used as a first layer, fringe distribution indicates cohesive fractures as a consequence of composite polymerization.

Clinical Relevance Many curing lights that are present in clinical practice today cause the clinician to wonder which curing unit is best for the photopolymerization of dental light curing materials. This study introduces the blue diode laser photopolymerization of composite materials, which, if acceptable for clinical use, offers the best polymeri...

A new technique capable of monitoring two-dimensional vibration fringe patterns in real-time is presented. It is based on optical reconstructing of time-averaged digital holograms. Recording of the holograms is realized in a quasi-Fourier off-axis setup whilst reconstructing in an extended Fourier transform setup capable of spatial filtering of the...

Clinical Relevance The use of a low intensity light source for photopolymerization based on LED technology provides equivalent final degree conversion with possible flow of the resin composite, similar to when QTH technology is used. At the same time, the lower temperature rise in the sample and the more favorable development of shrinkage kinetics...

This work reports on recent results in the area of the time-averaged digital holographic interferometry. Two techniques are described, one that removes the zero-order reconstruction term thus allowing recording of large objects, and the other by which the hidden stationary deformations can be detected. Quantifying hidden deformations is important b...

Composite materials shrink during the polymerization process which lessens their clinical value. Modifications of composition of the composite material and application technique proved inadequate for compensation of polymerization shrinkage, and therefore modification of polymerization modes was attempted. The polymerization modes of lower intensit...

A new device for measuring surface vibrations of musical instruments is presented. The architecture of the device is based on a quasi-Fourier digital holography setup with inexpensive commercial elements capable of recording large digital holograms. Experimental results showing vibration modes for several musical instruments are given. The results...

This study shows that a dynamic modal characterization of musical instruments with membrane can be carried out using a low-cost device and that the obtained very informative results can be presented as a movie. The proposed device is based on a digital holography technique using the quasi-Fourier configuration and time-average principle. Its practi...

Polymerization shrinkage is an unavoidable consequence of resin composite photopolymerization and is one of the most important factors in determining the clinical quality and durability of composite filling. Many different methods of measuring polymerization shrinkage are described in the literature. Digital laser interferometry is a method that en...

Polymerization of composite filling is considered to be an important factor in achieving longevity of the restorative treatment. Quality of the polymerization influences physico-mechanical characteristics, color stability, volumetric changes of restoration and biocompatibility of the material itself. Polymerization shrinkage is an unavoidable conse...

Digitalna holografska interferometrija nova je metoda za detekciju i mjerenje naprezanja nastalog zbog polimerizacijskog skupljanja prilikom cementiranja estetskih intrakanalnih kolčića adhezijskim dvostruko stvrdnjavajućim cementom. Holografska interferometrija omogućava određivanje točne veličine, gustoće i položaja deformacije kao i daljnju kval...

The forensic problem of identifying toolmarks is analysed and a method based on utilizing an optoelectronic correlator device as a possible solution is proposed. The method includes: acquiring striation patterns as digital files by using an environmental scanning electron microscope (SEM), selecting and extracting features from the striation patter...

A method of detecting displacements of a surface from its steady-state position to its equilibrium position while it is vibrating has been developed by use of time-average digital holographic interferometry. This method permits extraction of such a hidden deformation by creating two separated systems of interferogram fringes: one corresponding to a...

Time-averaged holographic interferometry is a known technique frequently used for analyzing vibration properties of objects. The development of array photo-detectors allowing long integration times enabled the capture of time-averaged holograms. A new technique called 'subtraction digital holography' has been recently developed for suppressing the...

Time-averaged holographic interferometry is a known technique frequently used for analyzing vibration properties of objects. The development of array photo-detectors allowing long integration times enabled the capture of time-averaged holograms. A new technique called `subtraction digital holography" has been recently developed for suppressing the...

The importance of spatial light modulators (SLMs) in optical systems is increasing. This paper presents our work on an SLM system based on Sony LCD. We show the optimisation of the LCD modulation behavior concerning the application as dynamical diffractive element, and the implementation of images and filter functions in optical correlators and pat...

Digital interferometry device is described for measuring the thickness variations of the resin composite samples during blue light polymerization. The proposed device enables two types of quantitative measurements providing data for: (i) the thickness variations of samples continuously during cure and (ii) the total linear shrinkage of samples. The...

Digital interferometry based device for measuring the thickness variations of the resin composite materials during blue light polymerization is described. The proposed device enables two types of quantitative measurements providing data for the total displacement and the dynamic behavior of displacement. The effect of the thermal expansion as well...

A color digital holographic interferometry movie was produced by applying the subtraction digital holography method in a quasi-Fourier off-axis experimental setup. The movie was numerically recorded and replayed from three sets of digital holograms obtained with three different laser lines (476 nm, 532 nm, and 647 nm). The movie shows convective fl...

A refined Fourier-transform method of analysis of interference patterns is presented. The refinements include a method of automatic background subtraction and a way of treating the problem of heterodyning. The method proves particularly useful for analysis of long sequences of interferograms.

Overlapping of the desired (first-order) and undesired (zero-order) terms originating from the recorded primary-fringe patterns in digital holography is a problem without a real-time solution. We propose a procedure for suppressing the zero-order disturbance that is realizable in real time. The procedure is based on the stochastic change of the spe...

A hybrid-optoelectronic correlator device and an algorithm are proposed for recognizing cuneiform inscription signs. The device is based on the extended correlator architecture with three liquid-crystal display(s) (LCD)s and three light detectors: one CCD camera for capturing the input image, one LCD for displaying the input image, two LCDs for the...

The detection and classification of faults is a major task for optical nondestructive testing in industrial quality control. Interferometric fringes, obtained by real-time optical measurement methods, contain a large amount of image data with information about possible defect features. This mass of data must be reduced for further evaluation. One p...

A 2D dynamic phase-modulating system (DPS) addressed by a digital signal at video frame rate can realize several optical transmission functions in the field of refractive as well as diffractive optics. Critical parameters are the space-bandwidth product, the phase shift and the light efficiency of the system. We demonstrate result of our current re...

The application of two dimensional addressable high resolution displays as spatial light modulators for the reconstruction of coherent masks is investigated. Based on their amplitude and/or phase modulating properties they are implementable as dynamic diffractive element and thus they are qualified for the efficient reconstruction of digital hologr...

Die Wavelet-Transformation hat sich als leistungsfähiges Werkzeug bei der Erkennung von Strukturen mit definierter räumlicher Auflösung erwiesen. Im vorliegenden Aufsatz wird die Filter-Prozedur in der komplexen Ebene nicht nur auf numerische Simulationen erweitert, sondern auch in optischen Experimenten durch einen zweifachen Frequenzebenen-Korrel...

The detection and classification of faults is a major task for optical non-destructive testing in industrial quality control. Interferometric fringes contain a large amount of image data with information about possible defect structures. This mass of data must be reduced for further evaluation. One possible way is the filtering of these images appl...

The wavelet transform has been proven to be a capable tool for the detection of structures with definite spatial resolution. In this work we extended the filtering procedure to the full complex plane not only in simulation but also in the optical verification by a double frequency plane correlator which is based on three twisted nematic liquid crys...

Holographic microscopy with conjugate reconstruction for the interferometric determination of three-dimensional displacement was used for the investigation of the mechanical behaviour of micromechanic and microelectronic components. An experimental set-up for the exposure of the holographic interferograms is described for the application of the spa...

Liquid crystal displays, originally designed and fabricated for projection systems, are often used as spatial light modulators in optical correlators or in fringe projection systems. Operating in a linearized phase mode, they can achieve a performance to be applicable as diffractive elements. An adapted driver electronics and adapting measurements...

Cuneiform inscriptions has been studied recently using holographically based methods. The goal was to preserve the written information by using the high-resolution and 3D possibilities of holographic recording as well as to investigate the cuneiform inscription signs in the sense of characterizing different types of writing. Here we present the exp...

Liquid crystal panels, originally designed and fabricated for projection systems, are used as spatial light modulator in optical correlators or in fringe projection systems. An adapted driver electronics and measurements of the phase modulation behavior can lead to a dynamic phase modulating system with an almost linear modulation and a maximum pha...

The detection and classification of faults is a major task for optical nondestructive testing in industrial quality control. Interferometric fringes, obtained by real-time optical measurement methods, contain a large amount of image data with information about possible defect features. This mass of data must be reduced for further evaluation. One p...

The importance of spatial light modulators (SLMs) in optical systems is increasing. This paper presents our work on an SLM system based on Sony LCD. We show the optimization of the LCD modulation behavior concerning the application as dynamical diffractive element, and the implementation of images and filter functions in optical correlators and pat...

Pattern recognition with coherent optical correlators was applied to different objects, among them handwritten documents [1,2]. A lot of investigations deal with character recognition, but only a few papers have analysed the relation between manuscript and writer. We used this method to analyse the origin of unknown manuscripts, which are of intere...

Compared to the classical VanderLugt correlator, optical- hybrid frequency plane correlator systems are more flexible, but also more complicated. Implementation of the hybrid systems requires the use of addressable spatial light modulators to display contents of the input and filter planes and the use of the additional lenses to match the scalings...

An optimization procedure for the optical implementation of correlation filters (CFs) in an optical-hybrid frequency plane correlator is presented. Our approach is based on mapping of the given calculated CF values to the values constrained by the available spatial light modulator device to achieve the maximum intensity of the output correlation pe...

Optical-hybrid correlator systems use electronically addressed spatial light modulators (SLMs) to improve the flexibility in data manipulation. By using the SLMs we must add to the optical setup such elements like polarizers and retarders, or enlarging lenses to match the scales in the system. These optical elements as well as the SLMs themselves c...

Holographic interferometry with three illumination directions can be applied to determine all components of a displacement vector without previous knowledge of the main deformation direction. Combined with a microscopic arrangement this method is utilized for the investigation of the operating parameters of sensor micro-components. The interferomet...

New holographic materials with high resolution broaden the possibilities of applications of color holography. The color rendering of two of these materials, the Russian silver halide material PFG 03 and DuPonts photopolymer, was investigated and compared. This was done by using the CIELAB color system, taken into account luminance, hue, and chromat...

Correlation filters (CFs) are designed for pattern recognition tasks, taking into account the implementation of possibilities of available spatial light modulators (SLMs). Commercially available SLMs have the amplitude and phase responses that cannot be independently controlled. Furthermore, the phase modulation curves of such SLMs generally cannot...

Holographic interferometry with three illumination directions can be applied to determine all components of a displacement vector without previous knowledge of the main deformation direction. Combined with a microscopic arrangement this method is utilized for the investigation of the operating parameters of sensor micro-components. The interferomet...

The use of liquid-crystal panels from a commercially available Sanyo video projector as spatial light modulators in a standard joint transform correlator system is investigated. It is found that the flatness distortion of the panels disturbs the output correlation signal in general. Since the reported solutions for the flatness corrections are eith...

Holographic microscopy for the simultaneous interferometric determination of all displacement components is described. The recording and the evaluation procedures are optimized by three illumination directions and conjugate reconstruction, respectively. Microscopic observation is completely separated from holographic recording. The holographic micr...