Adrian Sima - Academia.edu (original) (raw)

Papers by Adrian Sima

Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 2018

In this paper we apply digital holographic interferometry as a structural diagnosis tool to inves... more In this paper we apply digital holographic interferometry as a structural diagnosis tool to investigate some surface defects in a XIXth century wooden icon. We use a fully digital experimental set-up for real time acquisition and digital optical reconstruction of holographic sequences. The light source is a He-Ne laser, the digital recording component consists of a CCD camera and a spatial light modulator (SLM) works as a digital holographic projector for the optical reconstruction of the interferograms. Both the acquisition set-up and the reconstruction one are functioning simultaneously therefore the changes in the surface structure are visualized in real-time like a digital holographic interferometry “fringe motion picture” with a 20 fps display. Detachment defects of the paint layer are identified using this non-destructive method and the real-time feature has proven to be useful because it gave a very useful dynamicity to the entire investigation process.

Journal of Optoelectronics and Advanced Materials, 2010

In this paper we present some classical holographic experiments only this time performed in vario... more In this paper we present some classical holographic experiments only this time performed in various digital experimental arrangements. The information of the hologram is either calculated using discrete light diffraction formulae or recorded on a CCD, which takes the place of the registration holographic plate. The information of the hologram may be coded on a SLM which when illuminated reproduces the effects of the diffraction through the hologram or the diffraction may be calculated by a computer and so the output may be obtained more or less digitally. The distinction between virtual and actual digital is stressed. Experiments starting from the simple playback of computer generated Fourier holograms, going through basic interference experiments such as obtaining fringes of equal inclination up to more sophisticated configurations such as Fresnel holograms, are presented with a stress on the digital aspects that make these experiments depart from their classic counterpart.

2017 9th International Conference on Electronics, Computers and Artificial Intelligence (ECAI), 2017

Digital holographic interferometry (DHI) increases the advantages of analogical holographic inter... more Digital holographic interferometry (DHI) increases the advantages of analogical holographic interferometry because it eliminates the classical procedures for holographic interferogram acquisition and reconstruction, procedures which involves time and incommodious chemical processing. We propose an optical holographic reconstruction procedure which is faster than a computational one. In this paper we present a full digital experimental set-up used for real-time digital acquisition of a holographic frame sequence and also for real time optical holographic reconstruction using a He-Ne laser, a CCD camera and a phase only spatial light modulator (SLM) HEO1080 from HoloEye having a resolution of 1980×1080 pixels and a 15.36×8.64 mm active area size. Real-time DHI is performed by subtracting consecutive captured frames from a reference frame. A dynamic fringe pattern “motion picture” can be visualized through optical reconstruction. Object lateral displacements are visualized in real-time...

Advanced Topics in Optoelectronics, Microelectronics, and Nanotechnologies VIII, 2016

A fully digital experimental set-up for real-time digital acquisition and digital optical reconst... more A fully digital experimental set-up for real-time digital acquisition and digital optical reconstruction of holographic sequences is presented: a He-Ne laser, a CCD camera and a Phase Only Spatial Light Modulator (SLM) area are part of the set-up. CCD registering and SLM projector are working simultaneously. Using a custom made software of our own, real-time Digital Holographic Interferometry (DHI) “fringe motion pictures” can be performed by subtracting consecutive frames from a reference one and instantly displaying the differences on the SLM illuminated with a playback wave. Phase variations of the objects can be visualized in real-time by observing the interference fringe pattern evolution.

Advanced Topics in Optoelectronics, Microelectronics, and Nanotechnologies IV, 2009

Stationary Fizeau fringes, phase shift interferometric fringes, fringes obtained in Murty lateral... more Stationary Fizeau fringes, phase shift interferometric fringes, fringes obtained in Murty lateral shear interferometry, vibration interference pattern as seen by digital speckle pattern interferometer all are digitally captured in specific interferometer set- ups. IntelliWave software produced by Engineering Synthesis Design, Inc. (ESDI) is used to process the fringe patterns. For all these fringe patterns the physical principle and set up

Advanced Topics in Optoelectronics, Microelectronics, and Nanotechnologies IV, 2009

A spatial light modulator is a matrix-shaped device able to modify the amplitude or the phase of ... more A spatial light modulator is a matrix-shaped device able to modify the amplitude or the phase of the reflected or transmitted light, which can be operated pixel by pixel independently. This opens new possibilities for rapid and efficient manipulation of the light diffraction but also brings us close to the ambiguous boundary between physical and digital optics, or more precisely

This paper is concerned with the determination of in-plane displacements and deformations, by usi... more This paper is concerned with the determination of in-plane displacements and deformations, by using digital speckle correlation. A special algorithm for determining the position of the maximum of the correlation function is presented. An example on how to apply this method is presented.

In this paper we describe a traceable to the meter standard method to measure the height of an ar... more In this paper we describe a traceable to the meter standard method to measure the height of an artifact used as a calibrator for observation instruments in nanotechnologies and nanosciences. The artifact is a grating specially manufactured so that its features (height, pitch, width, wall angles) are highly uniform across its area. A Linnik microscope designed for longitudinal (vertical) measurements

In this paper we investigate the vibrations of a square aluminium plate by speckle interferometry... more In this paper we investigate the vibrations of a square aluminium plate by speckle interferometry means. Modes of vibration of this plate are shown as speckle interferograms. As usually is the case with such interferograms, enhancement and filtering of these images is needed after recording. The speckle index and the signal-to-noise ratio (SNR) of the preprocessed interferograms before and after

In this paper a Fourier transform digital holography experimental arrangement is presented. It is... more In this paper a Fourier transform digital holography experimental arrangement is presented. It is actually a hybrid arrangement, half digital half analog. The Fourier hologram was constructed using the analogous means of the so called lensless configuration. The hologram was recorded digitally by a camera with a large CCD array in stead of the recording medium. The recording of the

SPIE Proceedings, 2007

In this paper a simple method for determining the wavelength of an unknown source, (a problem of ... more In this paper a simple method for determining the wavelength of an unknown source, (a problem of great theoretical and practical importance), based on the Moire fringes phenomenon and Fourier analysis is presented and put into practice. The accuracy and the simplicity of the problem makes it attractive and competitive.

Applied Optics, 2017

Hadamard spectroscopy is a method of taking spectroscopic measurements suited to domains such as ... more Hadamard spectroscopy is a method of taking spectroscopic measurements suited to domains such as far infrared, where the sensor noise is dominant. Unfortunately, the signal-to-noise ratio of such a system scales poorly with the resolution. In this paper, we analyze a technique called microscanning that attempts to solve this problem by combining several lower resolution "preview" spectra to form a higher resolution spectrum. We provide a theoretical analysis of the method concerning the noise reduction and blurring. We conduct simulations based on the measured far infrared spectra of minerals in order to determine if the noise reduction can outweigh the loss in accuracy caused by the blurring effect, and we demonstrate the microscanning method in experimental conditions. We conclude that the microscanning method provides a noise reduction by a factor proportional to the number of previews and that it can be useful in far infrared spectroscopy.

Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 2018

In this paper we apply digital holographic interferometry as a structural diagnosis tool to inves... more In this paper we apply digital holographic interferometry as a structural diagnosis tool to investigate some surface defects in a XIXth century wooden icon. We use a fully digital experimental set-up for real time acquisition and digital optical reconstruction of holographic sequences. The light source is a He-Ne laser, the digital recording component consists of a CCD camera and a spatial light modulator (SLM) works as a digital holographic projector for the optical reconstruction of the interferograms. Both the acquisition set-up and the reconstruction one are functioning simultaneously therefore the changes in the surface structure are visualized in real-time like a digital holographic interferometry “fringe motion picture” with a 20 fps display. Detachment defects of the paint layer are identified using this non-destructive method and the real-time feature has proven to be useful because it gave a very useful dynamicity to the entire investigation process.

Journal of Optoelectronics and Advanced Materials, 2010

In this paper we present some classical holographic experiments only this time performed in vario... more In this paper we present some classical holographic experiments only this time performed in various digital experimental arrangements. The information of the hologram is either calculated using discrete light diffraction formulae or recorded on a CCD, which takes the place of the registration holographic plate. The information of the hologram may be coded on a SLM which when illuminated reproduces the effects of the diffraction through the hologram or the diffraction may be calculated by a computer and so the output may be obtained more or less digitally. The distinction between virtual and actual digital is stressed. Experiments starting from the simple playback of computer generated Fourier holograms, going through basic interference experiments such as obtaining fringes of equal inclination up to more sophisticated configurations such as Fresnel holograms, are presented with a stress on the digital aspects that make these experiments depart from their classic counterpart.

2017 9th International Conference on Electronics, Computers and Artificial Intelligence (ECAI), 2017

Digital holographic interferometry (DHI) increases the advantages of analogical holographic inter... more Digital holographic interferometry (DHI) increases the advantages of analogical holographic interferometry because it eliminates the classical procedures for holographic interferogram acquisition and reconstruction, procedures which involves time and incommodious chemical processing. We propose an optical holographic reconstruction procedure which is faster than a computational one. In this paper we present a full digital experimental set-up used for real-time digital acquisition of a holographic frame sequence and also for real time optical holographic reconstruction using a He-Ne laser, a CCD camera and a phase only spatial light modulator (SLM) HEO1080 from HoloEye having a resolution of 1980×1080 pixels and a 15.36×8.64 mm active area size. Real-time DHI is performed by subtracting consecutive captured frames from a reference frame. A dynamic fringe pattern “motion picture” can be visualized through optical reconstruction. Object lateral displacements are visualized in real-time...

Advanced Topics in Optoelectronics, Microelectronics, and Nanotechnologies VIII, 2016

A fully digital experimental set-up for real-time digital acquisition and digital optical reconst... more A fully digital experimental set-up for real-time digital acquisition and digital optical reconstruction of holographic sequences is presented: a He-Ne laser, a CCD camera and a Phase Only Spatial Light Modulator (SLM) area are part of the set-up. CCD registering and SLM projector are working simultaneously. Using a custom made software of our own, real-time Digital Holographic Interferometry (DHI) “fringe motion pictures” can be performed by subtracting consecutive frames from a reference one and instantly displaying the differences on the SLM illuminated with a playback wave. Phase variations of the objects can be visualized in real-time by observing the interference fringe pattern evolution.

Advanced Topics in Optoelectronics, Microelectronics, and Nanotechnologies IV, 2009

Stationary Fizeau fringes, phase shift interferometric fringes, fringes obtained in Murty lateral... more Stationary Fizeau fringes, phase shift interferometric fringes, fringes obtained in Murty lateral shear interferometry, vibration interference pattern as seen by digital speckle pattern interferometer all are digitally captured in specific interferometer set- ups. IntelliWave software produced by Engineering Synthesis Design, Inc. (ESDI) is used to process the fringe patterns. For all these fringe patterns the physical principle and set up

Advanced Topics in Optoelectronics, Microelectronics, and Nanotechnologies IV, 2009

A spatial light modulator is a matrix-shaped device able to modify the amplitude or the phase of ... more A spatial light modulator is a matrix-shaped device able to modify the amplitude or the phase of the reflected or transmitted light, which can be operated pixel by pixel independently. This opens new possibilities for rapid and efficient manipulation of the light diffraction but also brings us close to the ambiguous boundary between physical and digital optics, or more precisely

This paper is concerned with the determination of in-plane displacements and deformations, by usi... more This paper is concerned with the determination of in-plane displacements and deformations, by using digital speckle correlation. A special algorithm for determining the position of the maximum of the correlation function is presented. An example on how to apply this method is presented.

In this paper we describe a traceable to the meter standard method to measure the height of an ar... more In this paper we describe a traceable to the meter standard method to measure the height of an artifact used as a calibrator for observation instruments in nanotechnologies and nanosciences. The artifact is a grating specially manufactured so that its features (height, pitch, width, wall angles) are highly uniform across its area. A Linnik microscope designed for longitudinal (vertical) measurements

In this paper we investigate the vibrations of a square aluminium plate by speckle interferometry... more In this paper we investigate the vibrations of a square aluminium plate by speckle interferometry means. Modes of vibration of this plate are shown as speckle interferograms. As usually is the case with such interferograms, enhancement and filtering of these images is needed after recording. The speckle index and the signal-to-noise ratio (SNR) of the preprocessed interferograms before and after

In this paper a Fourier transform digital holography experimental arrangement is presented. It is... more In this paper a Fourier transform digital holography experimental arrangement is presented. It is actually a hybrid arrangement, half digital half analog. The Fourier hologram was constructed using the analogous means of the so called lensless configuration. The hologram was recorded digitally by a camera with a large CCD array in stead of the recording medium. The recording of the

SPIE Proceedings, 2007

In this paper a simple method for determining the wavelength of an unknown source, (a problem of ... more In this paper a simple method for determining the wavelength of an unknown source, (a problem of great theoretical and practical importance), based on the Moire fringes phenomenon and Fourier analysis is presented and put into practice. The accuracy and the simplicity of the problem makes it attractive and competitive.

Applied Optics, 2017

Hadamard spectroscopy is a method of taking spectroscopic measurements suited to domains such as ... more Hadamard spectroscopy is a method of taking spectroscopic measurements suited to domains such as far infrared, where the sensor noise is dominant. Unfortunately, the signal-to-noise ratio of such a system scales poorly with the resolution. In this paper, we analyze a technique called microscanning that attempts to solve this problem by combining several lower resolution "preview" spectra to form a higher resolution spectrum. We provide a theoretical analysis of the method concerning the noise reduction and blurring. We conduct simulations based on the measured far infrared spectra of minerals in order to determine if the noise reduction can outweigh the loss in accuracy caused by the blurring effect, and we demonstrate the microscanning method in experimental conditions. We conclude that the microscanning method provides a noise reduction by a factor proportional to the number of previews and that it can be useful in far infrared spectroscopy.