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We present the generation and 3D manipulation of microbubbles by thermal gradients, induced by low power nanosecond pulsed laser in non-absorbent liquids. Light absorption at photodeposited silver nanoparticles on the optical fiber tip heat up the surrounding liquid, which leads to optothermal effects. With each laser pulse a microbubble is detached from the optical fiber end, creating a microbubbles-stream. The microbubbles move away from the optical fiber end driven by non-spherical cavitation until they coalesce creating a main-bubble which is attracted towards the optical fiber end by Marangoni force. In addition, the main-bubbles are under the influence of buoyancy and gravity forces, which act upwards and downwards, respectively. The balance of these forces allows the 3D manipulation of the main-bubble. The main-bubble position can be controlled by careful control of the pulse energy. To our knowledge this is the first time that 3D manipulation of microbubbles using pulsed lasers is demonstrated.

Several water index-based methods have been proposed in the literature, which, combine satellite multispectral bands in an algebraic expression. The objective of these water index-based methods is to increase the intensity contrast between water-pixels (surface water-body) and non-water pixels (built-up, soil, vegetation, etc.). The present investigation evaluates the Modified Normalized Difference Water Index (MNDWI) and the Automated Water Extraction Index (AWEI) using the Satellite data from Landsat 5 TM, Landsat 8 and Sentinel 2A at different time scenes. Based on visual inspection of the Lake Metztitlan water body mapping results, a high performance of AWEI approached via the OLI and the MSI sensors is observed. In the selected study area of [9210x9380]m, a statistical water pixel percentage of 30.703616% is observed in a flooding season and 9.884537% for a dry season of the year.

Urban growth, deforestation, water resources and thawing of the poles due to globe worming are topics of interest in the research community. Normalize difference indices are utilized in remote sensing to analyzed and classify surface cover types. In this paper research, a multispectral satellite data from Landsat 5 TM is preprocessing, in order to addresses and evaluates accuracy of Normalized difference Built-up Index (NDBI), Normalized Difference Vegetation Index (NDVI), Automated Water Extraction Index (AWEI) and Normalized Difference Snow Index (NDSI) at different time scenes. A quantitative statistical pixel percentages of build-up, vegetation cover, snow/ice and water body is given in this study for different periods of time.

Nowadays, breast lesions are a common health problem among women. Breast thermograms are images recorded by digital-optical systems with high resolution that use infrared technology in order to show vascular and temperature changes. In the present work, we study benign and malignant breast lesions shape by means of fractal analysis. The Fractal Dimension (FD) is calculated with the Box Counting method and the Hurst exponent is obtained using the Wavelet coefficients and the Detrending Moving Average algorithm. These algorithms was applied to synthetic images and breast thermograms. The Fractal Dimension value is used for patient classification with or without breast injury. The proposed methodology was applied to the Database For Mastology Research (DMR) in order to classify thermographic images. The FD of ROIs for breast thermograms was calculated. Results shows that the FD BCM values ranges from [0.45,0.81] in 4 healthy cases and from [0.92,1.33] in 4 unhealthy cases.

Wavefront coding is a hybrid optical-computational technique that makes use of a phase modulating element in conjunction with a deconvolution algorithm to extend the depth of focus of imaging systems. The phase mask codes the wave-front in such a way that the point-spread function do not change appreciably as a function of defocus. In this work, the modulation is introduced by phase masks in the shape of a subset of Jacobi-Fourier polynomials. We will show, by both numerical simulations and experiments that the Jacobi-Fourier polynomial phase masks are good candidates for high-resolution images under noise presence.

A Wavefront Coding microscopy system is implemented in order to extend the depth of field of an optical system. An LC - SLM is used to display the profile of a phase mask. A set of optically coded images is recorded in an axial range [−1, 1.5] mm. To accelerate the deconvolution process, a routine developed directly on a GPU is implemented. Using this GPU based approach, the deconvolution time is reduced by providing an additional speed up to the visualization. Digital images are acquired using an experimental setup and results are presented.

Wavefront coding is an optical-digital technique that consists in introducing a suitable phase mask in the aperture plane able to extent, after image processing, the depth of field of an optical system. The key to wavefront coding lies in the shape of the phase masks to achieve the invariant imaging properties over the range of defocus. Cubic phase mask was the first proposed. Next, trefoil mask avoided periodic artifacts in the images keeping the goal of depth extension. The performance of the masks, resolution and noise of the coded images, depends on their strength, required range of defocus and f-number of the optical system. Here, we will provide the experiments that will support that a member of the Jacobi-Fourier phase masks can be chosen depending on the f-number of the optical system to get the best balance between resolution, noise level and artifact presences while keeping depth of focus.

Wavefront coding refers to the use of a phase modulating element in conjunction with deconvolution to extend the depth of focus of an imaging system. The coding element is an asymmetrical phase plate shape, for most applications in the form of a trefoil or a cubic polynomial. Phase plates with trefoil shape generate not only the desired amount of trefoil aberration but also spherical aberration. It has been recently shown that a wavefront coding based optical system shows high tolerance to spherical aberration for monochromatic images; however, the depth of focus is considerably shortened for color images. In this work, we will show how to modify the shape of a phase plate in order to optimize its performance for color imaging. The design parameters of the phase plate are obtained by minimizing a merit function by means of genetic algorithms developed for this purpose. The evaluation of the optical characteristics of the phase plates for a feedback with the optimization algorithm is obtained by Zemax. Results will be illustrated by numerical simulations of color images.

Breast thermography uses ultrasensitive infrared cameras to produce high resolution images of temperatures and vascular changes. In the present work we propose the development of computational methods that allow the analysis and digital processing of breast thermographic images for the detection of regions related to a probable lesion. A semi-automated segmentation algorithm is presented by means of polynomial curve Otting for the detection a region of breast (ROI). A public database which contains information on volunteers with diagnose made by mammography and biopsy is used.

Wavefront Coding (WFC) technique is typically used to compensate for optical aberrations related to defocus. An advantage of WFC are that the depth of field (DOF) will be increased and the weight and size of an optical system are reduced. In this work a WFC system is analyzed to extend the DOF of the microscope objective. The Point Spread Function (PSF) is used to modify in such a way that it is invariant to defocus in a range of axial distances. A liquid crystal display light modulator (LC − SLM) in a 4f imaging system is used for the implementation of the phase masks (PM). LC− SLM screens modulate both the amplitude and the phase of the input beam. This display allows a flexible implementation of different profiles of phase masks that are generated from different families of functions, this is because the parameters can be dynamically modified. In this document, we propose an experimental setup for extended DOF in optical microscopy. Experimental results are presented using a LC - SLM.

Generation and 3D manipulation of microbubbles by means of temperature gradients induced by low power laser radiation is presented. Photodeposited silver nanoparticles on the distal end of two optical fibers act as thermal sources after light absorption. The temperature rises above liquid evaporation temperature generating a microbubble at the optical fibers end in non-absorbent liquids. Alternatively, switching the thermal gradients between the fibers, it is possible to generate forces in opposite directions, causing the migration of microbubbles from one fiber optic tip to another. Marangoni force induced by surface tension gradients in the bubble wall is the driving force behind the manipulation of microbubbles

The generation and manipulation of microbubbles by means of temperature gradients induced by low power laser radiation is presented. A laser beam (λ = 1064 nm) is divided into two equal parts and coupled to two multimode optical fibers. The opposite ends of each fiber are aligned and separated a distance D within an ethanol solution. Previously, silver nanoparticles were photo deposited on the optical fibers ends. Light absorption at the nanoparticles produces a thermal gradient capable of generating a microbubble at the optical fibers end in non-absorbent liquids. The theoretical and experimental studies carried out showed that by switching the thermal gradients, it is possible to generate forces in opposite directions, causing the migration of microbubbles from one fiber optic tip to another. Marangoni force induced by surface tension gradients in the bubble wall is the driving force behind the manipulation of microbubbles. We estimated a maximum Marangoni force of 400nN for a microbubble with a radius of 110 μm.

Wavefront Coding (WFC) is a technique which makes use of generalized aspheric optics and digital signal processing to greatly increase the depth of focus and/or reduce the cost of imaging systems. Usually, cubic phase elements are employed to obtain images that are insensitive to defocus and some aberrations. In this work we will show how to optimize the design of a trefoil phase plate in order to optimize its performance for large amounts of defocus.

The detection of a temperature increase or hot spots in breast thermograms can be related with high metabolic activity of disease cells. Image processing algorithms to seek mainly temperature increases above 3°C which have a high probability of being a malignancy are proposed. Also a derivative operator is used to highlights breast regions of interest (ROI). In order to determinate a medical alert, a feature descriptor of the ROI is constructed using its maximum temperature, maximum increase of temperature, sector/quadrant position in the breast, and area. The proposed algorithms are tested in a home database and a public database for mastology research.

Wavefront Coding (WFC) systems make use of an aspheric Phase-Mask (PM) and digital image processing to extend the Depth of Field (EDoF) of computational imaging systems. For years, several kinds of PM have been designed to produce a point spread function (PSF) near defocus-invariant. In this paper, the optimization of the phase deviation parameter is done by means of genetic algorithms (GAs). In this, the merit function minimizes the mean square error (MSE) between the diffraction limited Modulated Transfer Function (MTF) and the MTF of the system that is wavefront coded with different misfocus. WFC systems were simulated using the cubic, trefoil, and 4 Zernike polynomials phase-masks. Numerical results show defocus invariance aberration in all cases. Nevertheless, the best results are obtained by using the trefoil phase-mask, because the decoded image is almost free of artifacts.

We propose an invariant description method based on Zernike moments to classify hand vein patterns from raw infrared (IR) images. Orthogonal moments provide linearly independent descriptors and are invariant to affine transformations, such as translation, rotation, and scaling. A mathematical expression is given to derive a set of moment invariants. The obtained features have all the properties of moment invariants with the additional feature of image contrast invariance. For dorsal hand vein pattern acquisition, an IR imaging system is implemented. Also, a public database is used for a palm vein recognition task. A correct rate classification (CRC) above 99.9% is achieved using a set of rotation, scale, and intensity Zernike moment invariants. Additionally, multilayer perceptron and K-nearest neighbors are used as classifiers having as input data the Zernike normalized moments. A discriminative feature evaluation of the image moments allows the reduction of the number of descriptors while maintaining a high classification rate of 99%. The efficiency of the moment descriptors is evaluated in terms of accuracy and reduced computational cost by (a) avoiding the necessity of a preprocessing stage and (b) reducing the feature vector dimension. Experimental results show that Zernike moment invariants are able to achieve hand vein recognition without image preprocessing or image normalization with respect to change of size, rotation, and intensity.

The physical shape of the hand vascular distribution contains useful information that can be used for identifying and authenticating purposes; which provide a high level of security as a biometric. Furthermore, this pattern can be used widely in health field such as venography and venipuncture. In this paper, we analyze different IR imaging systems in order to obtain high visibility images of the hand vein pattern. The images are acquired in the range of 400 nm to 1300 nm, using infrared and thermal cameras. For the first image acquisition system, we use a CCD camera and a light source with peak emission in the 880 nm obtaining the images by reflection. A second system consists only of a ThermaCAM P65 camera acquiring the naturally emanating infrared light from the hand. A method of digital image analysis is implemented using Contrast Limited Adaptive Histogram Equalization (CLAHE) to remove noise. Subsequently, adaptive thresholding and mathematical morphology operations are implemented to get the vein pattern distribution.

Wavefront coding is a technique that makes use of aspheric phase masks and image processing to greatly increase the depth of focus and/or reduce the cost of imaging systems. The phase mask adds a controlled amount of aberrations to the optical system in such a way that invariant imaging properties are achieved over a wide range of defocus. When aspheric phase plates are fabricated, their shape has to be carefully designed to avoid introducing other aberrations into the optical system, which could reduce its performance. In this work, we will show how inherent spherical aberration for trefoil-shaped phase plates reduces the quality of color images. Results will be illustrated with numerical simulations. We will show that a fourth-order polynomial added to a trefoil shaped phase mask can avoid the plate generating undesired spherical aberration that will affect the final quality of the decoded color images.