National Repository of Grey Literature 26 records found  previous11 - 20next  jump to record: Search took 0.01 seconds. 
COHERENCE-CONTROLLED HOLOGRAPHIC MICROSCOPY IN DIFFUSE MEDIA
Lošťák, Martin ; Komrska, Jiří (referee) ; Šerý, Mojmír (referee) ; Chmelík, Radim (advisor)
This thesis deals with imaging through diffuse media in coherence-controlled holographic microscope (CCHM) developed in IPE FME BUT. The mutual coherence function as well as the signal dependence on the lateral mutual shift between both arms of the CCHM are calculated. Both functions are related to each other. The latter dependence is measured experimentally. A principle of imaging with CCHM through diffuse media with both ballistic and diffuse light is explained by a simple geometrical model. This model is then verified experimentally by imaging a sample through diffuse medium. The point spread function (PSF) of CCHM for imaging through diffuse media is then calculated. Results of PSF calculation are proved experimentally.
Three-dimensional reconstruction of image in digital holographic microscopy
Týč, Matěj ; Chmelík, Radim (advisor)
This thesis deals with the topic of 3D image processing for digital holographic microscopy - numerical refocusing. This method allows to perform mathematically accurate defocus correction on image of a sample captured away from the sample plane and it was applicable only for images that were made made using coherent illumination source. It has been generalized to a form in which it is also applicable to devices that use incoherent (non-monochromatic or extended) illumination sources. Another presented achievement concerns hologram processing. The advanced hologram processing method enables obtaining more data mainly concerning precision of quantities from one hologram — normally, one would have to capture multiple holograms to get those. Both methods have been verified experimentally.
Mathematical Methods for Image Processing in Biological Observations
Zikmund, Tomáš ; doc. RNDr.Petr Matula, Ph.D. (referee) ; Krejčí, František (referee) ; Chmelík, Radim (advisor)
The dissertation deals with the image processing in digital holographic microscopy and X-ray computed tomography. The focus of the work lies in the proposal of data processing techniques to meet the needs of the biological experiments. Transmitted light holographic microscopy is particularly used for quantitative phase imaging of transparent microscopic objects such as living cells. The phase images are affected by the phase aberrations that make the analysis particularly difficult. Here, we present a novel algorithm for dynamical processing of living cells phase images in a time-lapse sequence. The algorithm compensates for the deformation of a phase image using weighted least squares surface fitting. Moreover, it identifies and segments the individual cells in the phase image. This property of the algorithm is important for real-time cell quantitative phase imaging and instantaneous control of the course of the experiment. The efficiency of the propounded algorithm is demonstrated on images of rat fibrosarcoma cells using an off-axis holographic microscope. High resolution X-ray computed tomography is increasingly used technique for the study of the small rodent bones micro-structure. In this part of the work, the trabecular and cortical bone morphology is assessed in the distal half of rat femur. We developed new method for mapping the cortical position and dimensions from a central longitudinal axis with one degree angular resolution. This method was used to examine differences between experimental groups. The bone position in tomographic slices is aligned before the mapping using the propound standardization procedure. The activity of remodelling process of the long bone is studied on the system of cortical canals.
COHERENCE-CONTROLLED HOLOGRAPHIC MICROSCOPE
Kolman, Pavel ; Křupka, Ivan (referee) ; Kozubek, Michal (referee) ; Chmelík, Radim (advisor)
ransmitted-light coherence-controlled holographic microscope (CCHM) based on an off-axis achromatic and space-invariant interferometer with a diffractive beamsplitter has been designed, constructed and tested. It is capable to image objects illuminated by light sources of arbitrary degree of temporal and spatial coherence. Off-axis image-plane hologram is recorded and the image complex amplitude (intensity and phase) is reconstructed numerically using fast Fourier transform algorithms. Phase image represents the optical path difference between the object and the reference arms caused by presence of an object. Therefore, it is a quantitative phase contrast image. Intensity image is confocal-like. Optical sectioning effect induced by an extended, spatial incoherent light source is equivalent to a conventional confocal image. CCHM is therefore capable to image objects under a diffusive layer or immersed in a turbid media. Spatial and temporal incoherence of illumination makes the optical sectioning effect stronger compared to a confocal imaging process. Object wave reconstruction from the only one recorded interference pattern ensures high resistance to vibrations and medium or ambience fluctuations. The frame rate is not limited by any component of the optical setup. Only the detector and computer speeds limit the frame rate. CCHM therefore allows observation of rapidly varying phenomena. CCHM makes the ex-post numerical refocusing possible within the coherence volume. Coherence degree of the light source in CCHM can be adapted to the object and to the required image properties. More coherent illumination provides wider range of numerical refocusing. On the other hand, a lower degree of coherence makes the optical sectioning stronger, i.e. the optical sections are thiner, it reduces coherence-noise and it makes it possible to separate the ballistic light. In addition to the ballistic light separation, CCHM enables us to separate the diffused light. Multi-colour-light
Microscopy of Time Variable Biologic Objects
Uhlířová, Hana ; Kozubek, Michal (referee) ; Peychl,, Jan (referee) ; Chmelík, Radim (advisor)
The subject of the PhD thesis is the application of a transmission digital holographic microscope (DHM) which was designed and constructed in the Laboratory of optical microscopy at the IPE BUT for the research of live cells dynamics. First part of the work is concerned with theoretical description of the microscope imaging properties dependent on the coherence of illumination. It is supplemented with experiments of imaging of a model and a real biological specimen. The following part describes construction modifications and innovations of the microscope and its equipment that enabled the utilization of the microscope for live cells observations. In the experimental part the methodology of live cells preparation and DHM imaging was worked out. The methodology was verified by the observation of cell dynamics during an apoptosis induced by the cytostaticum cis-platinum. Further experiments examined the dynamics of live cells in standard conditions and during a deprivation stimulus. A novel method of holographically reconstructed phase, named \uva{dynamic phase differences}, was set up to evaluate quantitative changes of cell mass distribution during the experiments. Depending on the degree of malignancy and density of cell outgrowth, various schemes of cancer cells behaviour during a specific reaction were revealed using this method. For the quantitative analysis of the DHM phase imaging, a suitable statistical characteristic and an interpretation of the measured data were proposed. Both of them were successfully applied for the comparison of cell motility of two cell types: parental and progeny cell lines. On the basis of the proposed processing, hypotheses describing the reaction mechanism of tumour cells to stress life conditions were established. In the conclusions we summarize our findings and suggestions for the construction and the applications of a new generation of the transmission DHM.
Fresnel Incoherent Correlation Holography (FINCH)
Bouchal, Petr ; Zemánek, Pavel (referee) ; Chmelík, Radim (advisor)
This master’s thesis develops a novel method of digital holography, from recent studies known as Fresnel Incoherent Correlation Holography (FINCH). The method enables the reconstruction of the correlation records of three-dimensional objects, captured under quasi-monochromatic, incoherent illumination. The experimental system is based on an action of a Spatial Light Modulator, driven by computer generated holograms to create mutually correlated beams. Both optical and digital parts of the experiment can be carried out using procedures of classical holography, diffractive optics and digital holography. As an important theoretical result of the master’s thesis, a new computational model was proposed, which allows to describe the experiment completely with respect to its two basic phases. The proposed model allows to understood the method intuitively and can be used additionally for analysis and interpretation of the imaging parameters and the system optimalization. The theoretical part of the master’s thesis also presents a detailed description of the correlation imaging based on an appropriate reconstruction process. Computational models were developed for both monochromatic and quasi-monochromatic illumination. In experimental part, all theoretical results were verified. The imaging parameters were examined using standard resolution target tests and appropriate biological samples. As an original experimental result, spiral modification of the system resulting in a vortex imaging was proposed and realized. Here, a selective edge enhancement of three-dimensional objects is possible, resulting in a significant extension of possible applications of the method.
Theoretical description of imaging by a digital holographic microscope
Slabá, Michala ; Komrska, Jiří (referee) ; Chmelík, Radim (advisor)
The diploma thesis deals with theory of imaging in a transmitted-light digital holographic microscope using partially coherent illumination. The influence of spatial and temporal coherence state on optical sectioning property is solved. The coherent transfer function is calculated. From this function imaging characteristics for a two-dimensional scattering object are derived depending on its defocus. Two different designs of microscopes developed in the Laboratory of optical microscopy in IPE FME BUT are considered.
Illuminating system for a tandem-scanning confocal microscope
Slabý, Tomáš ; Kršek, Jiří (referee) ; Chmelík, Radim (advisor)
The diploma thesis deals with a design of illuminating system for tandem-scanning confocal microscope using a high-power LEDs.
Programmable illuminating system for an optical microscope
Lošťák, Martin ; Křupka, Ivan (referee) ; Chmelík, Radim (advisor)
A programmable illuminating system (PIS) uses a commercial multimedia projector together with a suitable optical relay system in order to illuminate specimens under microscope with transmitted light. The theoretical part of the diploma thesis describes some methods used in the optical transmission microscopy. All of these methods employ physical masks placed in the condenser front focal plane. In the case of the traditional methods the masks are used to enhance contrast (e.g. dark-field illumination) and resolution (oblique illumination). One of the methods (a condenser with rotating aperture) provides the information about the three-dimensionality of the specimen. The next part of the thesis contains the theory and the basic classification of the illuminating systems used in the optical transmission microscopy. An optical and mechanical design of the optical relay system used for PIS is introduced. The experimental part shows the results made with two different PIS arrangements. It was shown on two different specimens that the PIS provides the same illumination as the classical methods. It was also proved that the PIS can simulate the rotating aperture in the condenser front focal plane and thus to give the information about the three-dimensionality of the specimen. Some new static and dynamic illuminating methods were introduced.

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