Digital Image Plane Holography (DIPH) is a non-invasive optical technique which is able to recover the whole object wave. An object is illuminated and the diffused backscattered light is carried to a digital sensor by using a lens, where it interferes with a divergent reference wave with its origin in the lens aperture plane. Selecting each aperture image in the Fourier plane, the amplitude and the phase of the object beam are obtained. If two holograms are recorded at different times, after a small displacement, the reconstructed intensity distributions can be taken as a speckle field, while the phase difference distribution can be analyzed by an interferometric approach. In this work scattering media are investigated by using digital holography. The aim of this paper is to determine the viability of the technique to characterized optical properties of the sample. Different scattering media are modeled with different scattering properties. Each model generates a speckle pattern with different statistical properties (size, contrast, intensity). Both the visibility of the interferometric fringes and the properties of speckle pattern are related with optical properties of the media such as absorption and scattering coefficient. The ability to measure these properties makes the technique a promising method for biomedical applications.
The applications of nanoparticles in optical techniques of diagnosis and treatment of biological tissues are increasing. Image contrast can be improved in diagnostic approaches such as fluorescence, spectroscopy or optical coherence tomography. The therapeutic effect can be increased if nanoparticles are previously incorporated in the biological tissue. This is the case in thermotherapy, or in Photodynamic Therapy. All these applications take advantage of specific properties of the nanoparticles involved, either optical up- or down-conversion, thermal confinement or the ability to act as a drug-carrier. <p> </p>Although many biomedical applications that involve nanoparticles are being proposed and tested, there is a need to take into account the influence of those nanoparticles on optical radiation propagation. The previously mentioned optical treatment and diagnosis techniques assume a particular optical propagation pattern, which is altered by the addition of nanoparticles. This change depends on the nanoparticle material, shape, size and concentration, among other parameters. In order to try to quantify these changes, in this work several phantoms that include different nanoparticles are analyzed, in order to estimate the influence of nanoparticles in optical propagation. A theoretical model of optical propagation, which takes into account the absorption and scattering changes in the medium, is also considered. Nanoparticles of different sizes from 40 nm to 1 μm are analyzed. Nanoparticle materials of interest in biomedical applications are employed. The results are relevant in diagnosis interpretation of images and treatment outcome evaluation when nanoparticles are present.
The complete measurement of the blood velocity and the vein wall deformation is important in order to obtain the wall
shear stress distribution in blood vessels. This information would facilitate the diagnosis and treatment of some
In this work, endoscopy has been combined with high speed Particle Image Velocimetry (PIV) to obtain the flow
velocity inside a transparent vessel model and with digital holography to measure the vessel wall deformation. The use
of endoscopes presents different advantages: they allow the simultaneous illumination and imaging of the object under
inspection; the endoscopes can be moved as close as required and can be located anywhere to observe different regions.
They can be used for observing inside opaque vessels in an oblique way, where the image perspective distortion can be
High speed PIV and endoscopic PIV have been applied to evaluate the influence of an antithrombotic filter in the
velocity field inside an inferior vena cava (IVC) model. Endoscopic digital holography has been developed to measure
the wall deformation in vessel models with steady and pulsatile flows. The models present different flexibility and
opacity grades. Both the vessel model and the endoscope end are immersed in a refractive index matching liquid in order
to avoid distortions.
Digital Speckle Pattern Interferometry (DSPI) has been applied to measure shape of solid rough objects. A two
wavelength setup with one single recording has been applied. Spatial Phase Shifting techniques, with different carrier
fringes for each wavelength, have been used in order to produce a spatial multiplex. Selecting each aperture image in the
Fourier plane, the amplitude and the phase of the object beam is obtained for each wavelength. The subtraction of those
waves produces a wrapped phase map that can be considered a contour line map for a synthetic wavelength. The
technique has been applied in different material and the visibility of the fringes is observed. The possibilities and limits
of the technique have been analyzed.
In this work endoscopy has been combined with high speed PIV and holographic interferometry for flow velocity and wall deformation measurement of different vessels. Endoscopes have been used for illumination and/or recording of PIV images and digital holograms. High speed PIV has been applied to evaluate the influence of an antithrombotic filter in a vena cava model flow. Qualitative wall deformation has been obtained using digital holography in a vein model and in a real sheep aorta.
In this work a new application of digital holography for the study of cardio vascular diseases is proposed. The
simultaneous measurement of the blood flow velocity and the vein wall deformation can be obtained by combining
digital holography and endoscopy. Endoscopes are used for the illumination and recording of digital holograms inside a
vein model. Two different endoscopes have been used in different vein models in order to test the technique
performance. Preliminary results of flow velocity and wall deformation are presented.