We report coherent anti-Stokes Raman scattering (CARS) microscopy with ns-pulses. The chosen wide-field geometry allows imaging of the whole field of view at once, without scanning of the sample. Tuning the difference of the two incident laser frequencies overlapping at the sample to a specific vibrational level, one can map the spatial distribution of selected Raman active molecules. Both the CARS signal of the surrounding solvent can be excited (negative contrast) as well as the signal of the structure embedded by the solvent (positive contrast). As a biological sample we used slices of a sunflower seed and tuned to the vibrational transition of its ingredient - linoleic acid - at 2870 cm^-1 which corresponds to the strongest C-H stretching vibration. Even with a single pair of laser pulses of 3 ns duration it was possible to acquire a rough, but still meaningful image.

In this work we propose a new low-cost and compact optoelectronic system for optical mammography trials based on the use of low-cost semiconductor lasers and Si photodetectors. This system is completed using a versatile electronic architecture based on COTS (Cost-Off-The-Shelf) telecom components and techniques. The system is also designed for experimental studies on the dependence of the modulation frequency and the optimum signal to noise ratio (SNR). Results presented in this paper show the effect the modulation frequency and index has on the phase of the signal when passing through a commonly used scattering medium.

In this work the statistical pattern recognition methods were applied for evaluation of transillumination images of interphalangeal joints of patients suffering from rheumatoid arthritis. Special portable apparatus was constructed for performing the transillumination examination. It consisted of He-Ne laser with optics for collimated illumination, special holder for placing the finger (perpendicular to optical axis, dorsal site towards camera), and CCD camera with memory stick. 20 ill patients and 20 healthy volunteers were examined. The captured images with 1152x864 resolution were converted into the gray level pictures and analyzed by means of statistical pattern recognition method. Principal Component Analysis (PCA) and cluster analysis by use of 1-NN method (1 Nearest Neighbour) were applied for classification. The recognition system was able to differentiate correctly between healthy and ill subjects with 72.35% accuracy in case the data base composed of 40 persons.

According to the necessity of supporting vestibular schwannoma surgery, there is a demand to develop a convenient method of medical data visualization. The process of making choice of optimal operating access way has been uncomfortable for a surgeon so far, because there has been a necessity of analyzing two independent 3D images series (CT -bone tissues visible, MRI - soft tissues visible) in the region of ponto-cerebellar angle tumors. The authors propose a solution that will improve this process. The system used is equipped with stereoscopic helmet mounted display. It allows merged CT and MRI data representing tissues in the region of of ponto-cerebellar angle to be visualized in stereoscopic way. The process of data preparation for visualization includes: -automated segmentation algorithms, -different types of 3D images (CT, MRI) fusion. The authors focused on the development of novel algorithms for segmentation of vestibular schwannoma. It is important and difficult task due to different types of tumors and their inhomogeneous character dependent on growth models. The authors propose algorithms based on histogram spectrum and multimodal character of MRI imaging (T1 and T2 modes). However due to a variety of objects the library of algorithms with specific modifications matching to selected types of images is proposed. The applicability and functionality of the algorithms and library was proved on the series of data delivered by Warsaw Central Medical University Hospital.

We use a high resolution liquid crystal spatial light modulator (SLM) as phase modulator to generate different kinds of filters for light microscopy, placing it in a Fourier plane of the optical pathway. Manipulating light with a so called phase vortex filter can lead to an interesting kind of phase contrast imaging with remarkable properties. Using spatial coherent illumination from a laser diode, we observe strong edge enhancement within both phase and amplitude objects. The amplification is comparable to the Nomarski method, but with a higher degree of isotropy. The assembly can also provide an informative "shadow effect" (known as pseudo-relief) for shallow structures whose variations in thickness are smaller than the light wavelength. Furthermore, the method may be useful for an alternative kind of interferometric measurements, which solves an existing problem in conventional interferometry.

This paper summarizes the accomplishments to date in the development of the "artificial eye" - a fully functional eye prosthesis - which we hope to use in the future as an implant in people who have lost their vision due to eye damage. The future work necessary to bring the eye project to fruition is explained, and two important tasks, which we do not yet know how to solve, are described in the hope of stimulating a broad discussion within the scientific community. The summary of the historical developments in this field is followed by our accomplishment. The components of the eye that have been developed and tested to date are color processing receptive fields, variable-focus lenses, and local and global brightness adaptation systems. A constraint imposed on the components of the artificial eye is the requirement of minimal or no power draw. Following this condition, the components were developed using mainly passive, photonic properties of nonlinear optical materials. Color receptive fields are fabricated of photo-luminescent concentrators and photovoltaic detectors set in a multilayer stacked system allowing for color processing. Local and global adaptation is accommodated using the photochromic properties of some nonlinear optical materials. A variable focus lens is made of transparent elastic membranes filled with a refractive liquid, and focal length is changed by radial stretching. This modification to the lens was made to accommodate cataract patients. Two important aspects of the research, which are yet unsolved, include proper encoding of visual signals before transmission to the brain and methods for physical transmission of the encoded signals to the visual cortex.

The pre-ocular tear film is the most anterior refractive surface of the eye. Its stability plays an important role in the condition of vision from the optical and physiological point of view. If the eye is opened for a significantly long time or suffers from an anormalities in tear production, there appear isolated dry islands - break-ups - with a random distribution in the continuous lacrimal film. We applied an interferometric method - Lateral Shearing Technique for investigating the tear film stability and the smoothness of the tear film surface. This method is non-invasive and it is characterised by the high accuracy and sensitivity. Interferometry allows dynamic measurements of the tear film stability in real time by observation of interference fringes. The evaporation of tears and appearance of the breakups causes changes in the fringe geometry. Fast Fourier Transform has been used for quantitative assessment of the fringe smoothness and as a consequence of the tear film surface geometry. This paper presents the method used for quantitative evaluation of the tear film distribution on the cornea. Examples of interferograms recorded on eyes of patients with healthy eyes, suffering from dry eye syndrome and wearing contact lenses are also given. With our technique we were able to observe distinct differences in stability of the tear film between healthy and dry eyes, and the tear film on contact lenses.

We started our study with a group of Mexican Males with an Uncorrected Visual Acuity (UCVA) of 20/20, 20/30, and 20/40. The data was obtained using a Nidek OPD Scan ARK 10000 with the Version 1.11b of the working software. With the resulting Zernike coefficients, we calculated the average of the total Wavefront map, the Point Spread Function (PSF), the Optical Transfer Function, (OTF) and the corresponding Modulation Transfer Function (MTF). The purpose of these calculations was to obtain a pattern to be used as a reference to compare with the performance of human eyes after a laser surgery procedure and virgin eyes. In our case, the surgery was performed with an excimer laser Nidek EC-5000 Ver.1.26 W. When the OPD Scan software was upgraded, we realized that the Zernike coefficients for a given eye were different, for each version. Therefore, the aim of this work is to compare our reference pattern of the Zernike coefficients obtained with two different version of the working software.

Spectral Optical Coherence Tomography is a new modality to be introduced in ophthalmology. It introduces several improvements such as real-time and 3-dimensional imaging, and possibility of tomographic films, due to high speed of imaging offered by the method. For the same reason -- 2-dimensional cross-sectional images now can be performed with higher sampling density, which increase the signal-to-noise ratio. We analyze advantages and possible problems which may arise with the high speed imaging.

The blood vessels under skin layers are imaged on the basis of diffuse reflection measurement. The diffuse reflectance is defined by a probability density function of optical path-lengths when an absorber is embedded in a medium. Theoretical prediction of the dependence of the diffuse reflection on the depth of the absorber is confirmed by experiments. The possibility of the real-time imaging of blood vessels under skin layers is examined by using a 2D resonant mirror scanner. The potential of the new diffusing light topographic method is shown by experiments.

New image processing methods and active photonics apparatus have made possible the development of relatively inexpensive optical systems for complex shape and object measurements. We present dynamic 360° scanning method for analysis of human lower body biomechanics, with an emphasis on the analysis of the knee joint. The anatomical structure (of high medical interest) that is possible to scan and analyze, is patella. Tracking of patella position and orientation under dynamic conditions may lead to detect pathological patella movements and help in knee joint disease diagnosis. The processed data is obtained from a dynamic laser triangulation surface measurement system, able to capture slow to normal movements with a scan frequency between 15 and 30 Hz. These frequency rates are enough to capture controlled movements used e.g. for medical examination purposes. The purpose of the work presented is to develop surface analysis methods that may be used as support of diagnosis of motoric abilities of lower limbs. The paper presents algorithms used to process acquired lower limbs surface data in order to find the position and orientation of patella. The algorithms implemented include input data preparation, curvature description methods, knee region discrimination and patella assumed position/orientation calculation. Additionally, a method of 4D (3D + time) medical data visualization is proposed. Also some exemplary results are presented.

The paper presents a digital analysis of autofluorescence endoscope images in real time. The numerical analysis allows us to define with close approximation the area of cancerously changed tissue in real time.

The reflection of light by a semi-infinite biological medium is modeled by using a combination of finite multiplicity scattering and the diffusion approximation employing the Monte Carlo simulation. The solution to the radiative transfer equation (RTE) is represented as a sum of two terms. The first one is backscattered radiation with a scattering order of no greater than N. The second term represents a convolution of the RTE Green function and an effective source function of an order of (N + 1). The first term and the effective source are calculated using the Monte Carlo method, and the RTE Green function is obtained in the diffusion approximation. The solution to the problem of light reflection obtained by using the hybrid approach is compared to the results of the Monte Carlo simulation. The finite scattering order N , which provides a relatively high accuracy of the above hybrid method in the optical study of biological media, is estimated with respect to anisotropy factor and albedo of a single scattering event.

Optical imaging is a non invasive way to characterise turbid media, which is of real interest for investigating biological tissues for diagnosis purposes. A method called Integral Reflectance (IR) has already been developed [1]. The media being illuminated by a laser beam (670 nm, <1 mW), the backscattered light is captured by a 2D CCD camera. The reduced scattering coefficient μ's and the absorption coefficient μ_a are determined from the image. Having μ's and μ_a, the objective is to improve the characterization by estimating the anisotropy factor g, using polarized light. Different patterns depending on g are produced in these images, presenting some lobes, centred in the entry point of the laser beam, whose number and shape vary with g. To assess a simple description of these patterns, a circular outline of the image, at a given radius, is studied by Fourier series decomposition, namely Fourier descriptors, whose indices, modulus and phase provide the number, the size and the orientation of the lobes, respectively. Backscattered images of turbid media with g in the range [0.006 ; 0.93] (μ's = 10, 20, 40 cm^-1 ; μ_a = 0.01, 1, 5 cm^-1), were simulated using a Monte Carlo code for polarized light. Tables of Fourier descriptors were obtained as function of g, μ's and μ_a. Five reference solutions made of polystyrene spheres in liquid, with g varying from 0.71 to 0.919 (tissue phantoms) were tested. The Fourier descriptors were compared to simulations, and g could be retrieved with a maximum error of 10%.

The opportunities and features of applying multi-focused antennae based on Fresnel lens to the problems of acoustical brightness thermometry have been studied. The technical feasibility of the device equipped with these antennae has been analyzed. The method has been suggested for the optimization of choosing radii of Fresnel lens rings providing acceptable focusing quality at various distances taking into account the peculiarities of acoustical brightness thermometry -- wide-band signal receiving in millimeter range and frequency-dependent acoustical absorption.

In this study we evaluate the performance of several lossless grayscale image compression algorithms: algorithms that are standards in medical image transmitting and archiving systems, other algorithms used for compressing medical images in practice and in image compression research, and of a couple of universal algorithms applied to raw and preprocessed image data. In the experiments we use a new, publicly available, test image set, which is described in detail in the paper. The set contains about one hundred images, mainly medical images of various modalities (CR, CT, MR, and US) and natural continuous tone grayscale images of various sizes and various bit depths (up to 16 bits per pixel). We analyze algorithm performance with respect to image modality, depth, and size. Our results generally adhere to results reported in other studies, however, we find that some common opinions on performance of popular algorithms are imprecise, or even false. Most interesting observation concerning the compression speed is that the speed of many algorithms is relatively low, e.g., JPEG2000 obtains speed close to CALIC algorithm, which is considered to be slow. On the other hand there exist algorithms much faster than the JPEG-LS (i.e., SZIP and SFALIC). Considering the compression ratio, the most interesting results were obtained for high bit depth medical CT and MR images, which are of sparse histograms. For better compression ratios of those images, instead of standard image compression algorithms, we should either use universal algorithms or employ the histogram packing technique prior to actual image compression.

The subject of this paper concerns advanced techniques of procedures and imaging used in minimally invasive surgery and in non-operable cases of the alimentary tract tumor therapy. Examples of videoendoscopy and X-ray imaging used for the application of stents (prostheses) and catheters allowing for the performance of diagnostic and endo-therapeutic procedures are described. The possibility was indicated to elaborate a new method of proceeding in tumor therapy in the patients for whom the methods used so far were ineffective. In the paper examples of combined imaging the application of metallic stents and plastic catheters allowing for the performance of diagnostic and therapeutic procedures are presented. The cases shown refer to tumor located in the esophagus and in the bile and pancreatic ducts.

The multi-modal miniature microscope (4M) device to image morphology and cytochemistry in vivo is a microscope on a chip including optical, micro-mechanical, and electronic components. This paper describes all major system components: optical system, custom high speed CMOS detector and comb drive actuator. The hybrid sol-gel lenses, their fabrication and assembling technology, optical system parameters, and various operation modes (fluorescence, reflectance, structured illumination) are also discussed. A particularly interesting method is a structured illumination technique that delivers confocal-imaging capabilities and may be used for optical sectioning. For reconstruction of the sectioned layer a sine approximation algorithm is applied. Structured illumination is produced with LIGA fabricated actuator scanning in resonance. The spatial resolution of the system is 1 μm, and was magnified by 4x matching the CMOS pixel size of 4 μm (a lateral magnification is 4:1), and the extent of field of the system is 250μm. An overview of the 4M device is combined with the presentation of imaging results for epithelial cell phantoms with optical properties characteristic of normal and cancerous tissue labeled with nanoparticles.

The features of the application of the thermal imaging for examination of the oncological patients are considered. The capability of the fractal encoding for processing of the medical thermograms are analyzed. The main goal of this paper is characterization for fractal image encoding with quadtree partitioning and with self-organizing network. The using of these parameters must make sure the optimum relationship between the visual quality of the decoding thermograms and size of the files where these thermograms are saved. The algorithm for increasing of the linear size for fragments of the traced thermal medical images is developed. This method is based on combination of the tradition approach to interpolation (image resampling by bicubic, bilinear and nearest neighbour interpolation) and "fractal zoom". The integral quality coefficient, which is included, the evaluations of the level for adaptation of the human visual system, reliance of the available luminance range and combined thermal photo's contrast is used as evaluation of the visual quality for processed images.

Ultrasounds have been used widely in medicine and devices which using acoustic waves have been giving more and more information in medicine. We propose the solution that based on phase analysis of acoustic wave packet in medicine diagnosis of soft tissue tumor. The aim of these investigations has been a construction of such a device and algorithm that would enable to find new diagnostic applications. Experimental results of 2D visualization of phase relations between acoustics fields are presented. For ~1.5MHz frequency ultrasound signal, the proposed method could measure phase relations with resolution ~0.05 rad.

Wavelet transformation localizes all irregularities in the scene. It is most effective in the case when intensities in the scene have no sharp details. It is the case often present in a medical imaging. To identify the shape one has to extract it from the scene as typical irregularity. When the scene does not contain sharp changes then common differential filters are not efficient tool for a shape extraction. The new 2-D wavelet for such task has been proposed. Described wavelet transform is axially symmetric and has varied scale in dependence on the distance from the centre of the wavelet symmetry. The analytical form of the wavelet has been presented as well as its application for details extraction in the scene. Most important feature of the wavelet transform is that it gives a multi-scale transformation, and if zoom is on the wavelet selectivity varies proportionally to the zoom step. As a result, the extracted shape does not change during zoom operation. What is more the wavelet selectivity can be fit to the local intensity gradient properly to obtain best extraction of the irregularities.

The examination of quality of the sperm ejaculate is one of the most important steps in artificial fertilization procedure. The main aim of semen storage centres is to characterise the best semen quality for fertilization. Reliable information about sperm motility is also one the most important parameters for in vitro laboratory procedures. There exist very expensive automated methods for semen analysis but they are unachievable for most of laboratories and semen storage centres. Motivation for this study is to elaborate a simple, cheap, objective and repeatable method for semen motility assessment. The method enables to detect even small changes in motility introduced by medical, physical or chemical factors. To test the reliability of the method we used cryopreserved bull semen from Lowicz Semen Storage Centre. The examined sperm specimen was warmed in water bath and then centrifuged. The best semen was collected by the swim-up technique and diluted to a proper concentration. Several semen concentrations and dilutions were tested in order to find the best probe parameters giving repeatable results. For semen visualization we used the phase-contrast microscope with a CCD camera. A PC computer was used to acquire and to analyse the data. The microscope table equipped with a microscope glass pool 0.7mm deep instead of some conventional plane microscope slides was stabilised at the temperature of 37°C. The main idea of our method is based on a numerical processing of the optical contrast of the sperm images which illustrates the dynamics of the sperm cells movement and on appropriate analysis of a grey scale level of the superimposed images. An elaborated numerical algorithm allows us to find the relative amount of motile sperm cells. The proposed method of sperm motility assessment seems to be objective and repeatable.

The molecular complementarity of two strands of the DNA double helix makes it possible to model changes in DNA sequences basing on their optical properties. The paper is devoted to problems with reliability of fluorescence analysis in investigating DNA chains. A given oligonucleotide library makes a matrix of integrated short sequences which all have their own location and base sequence. The fluorescence effects may be acquired using a CCD camera, converted to digital microimages and stored. In the paper the physical aspects of fluorescence phenomena have been described. The mathematical model for tests tending to determine optimum algorithms of oligonucleotide library detection are proposed. Application of selected algorithms of image processing has been analyzed for conditioning microimages. The results obtained of binarization using digital filtration are presented. The optimal algorithm of image binarization has been shown.

The experimental system was constructed for development and evaluation of visual brain potentials detection algorithm. Our experimental system consists of the developed, spherical, LED based perimeter head, a portable EEG recorder and a PC as a multitask unit. The computer enables full control of perimeter stimulation as well as acquisition and analysis of recorded EEG signals, using for visual response detection the newly developed VEPDA algorithm. Application of the VEPDA algorithm, based on Independent Component Analysis, allows much faster detection of visual evoked potentials comparing to traditional trial averaging routines. Main outcomes of this new approach are high reliability, considerable shortening of the examination time as well as possibility of objective examination - even patients not able to respond consciously, as very young children or elderly and intellectually handicapped patients.

In this communication, the authors have determined the longitudinal chromatic aberrations in real eyes. The method that has been used combines real data of corneal morphology, central thickness of crystalline lens and biometric measures of axial length together with numerical calculation of the propagation process. The curvature of the crystalline lens has been adjusted to different curvature models and refractive index distributions. The wavelength dependence of all ocular media has been modelled through the Cauchy formula. Propagation through anterior and posterior chambers has been accomplished through numerical calculation of diffraction integral instead of classical ray-tracing approach. This imposes serous restrictions on the number of samples that are needed for a full propagation process. If we are only interested in amplitude calculations the method consists of evaluating propagation from cornea to crystalline lens with a spectrum propagation method. Propagation from the lens to the best image plane is accomplished by a direct calculation of Fresnel integral. With this model, we have obtained the refraction chromatic difference in diopters for several eyes. Results are compared with real measures of the chromatic aberration, showing a good agreement with numerical calculations. The capabilities of the technique have been demonstrated by applying the method to the study of the chromatic aberration of a keratoconus.

Most single-frame single-band medical images, like CR, CT, and MR, are of a high nominal bit depth, which usually varies from 12 to 16 bits per pixel. The actual number of pixels' intensity levels found in those images may be smaller, than implied by the nominal bit depth, by an order of magnitude or even more. Furthermore, levels are distributed throughout almost all the entire nominal intensity range, i.e., the images have sparse histograms of intensity levels. Image compression algorithms are based on sophisticated assumptions as to characteristics of the images they process. Sparse histogram is clearly different from what is expected by lossless image compression algorithm, both in case of predictive and of transform coding. To improve the compression ratios of such images, a method of histogram packing was recently introduced. The method is found to be effective, however, the research was done for low bit depth images. In this paper, we investigate effects of packing histograms of high bit depth medical images. We analyze an off-line packing method and find it to be highly effective. The off-line packing requires the information, describing how to expand the histogram after decompressing an image, to be encoded along with the compressed image. We present an efficient method of encoding this information. Experiments are performed for CALIC, JPEG2000, and JPEG-LS. The effects of packing histograms on the compression ratios of tested algorithms are, for all the tested algorithms, very similar. The average compression ratio improvement obtained for the CR, CT, and MR images is about 15%, 42%, and 52% respectively.

In the paper we present a method of optical tomography imaging based on the polarization analysis of the scattered photons. By using the Mueller - Stokes formalism we calculated Mueller matrix elements from measurements of the Stokes vector parameters of the light scattered during the angular scanning procedure. Analysis of the changes in the Mueller matrix elements allows recognizing a position of the objects in high scattering medium. Tests of the polarization optical tomography method were carried out with a narrow laser beam (λ=660nm, Ρ=35mW) illuminating a plastic container with Intralipid - a liquid simulating living tissue. The objects to be recognized were made in form of cylindrical probes introduced into a container filled with a solution of the same Intralipid with different optical density in comparison to a liquid inside the container.

Investigation of physical-mechanical characteristics of stomatologic materials (ceramics for crowns, silver amalgam, cements and materials on a polymeric basis) properties by the modern methods and correspondence their physical-mechanical properties to the physical-mechanical properties of native teeth is represented. The universal device "Micron-Gamma" is built for this purpose. This device allows investigate the physical-mechanical characteristics of stomatologic materials (an elastic modulus, micro-hardness, destruction energy, resistance to scratching) by the methods of continuous indentation, scanning and pricking. A new effective method as well as its device application for the investigation of surface layers of materials and their physical-mechanical properties by means of the constant indenting of an indenter is realized. This method is based on the automatic registration of loading (P) on the indenter with the simultaneous measurement of its indentation depth (h). The results of investigations are presented on a loading diagram P=f(h) and as a digital imaging on the PC. This diagram allows get not only more diverse characteristics in the real time regime but also gives new information about the stomatologic material properties. Therefore, we can to investigate the wide range of the physical-mechanical properties of stomatologic materials. "Micron-alpha" is digital detection device for light imaging applications. It enables to detect the very low material surface relief heights and restoration of surface micro topography by a sequence data processing of interferential data of partially coherent light also. "Micron-alpha" allows: to build 2D and 3D imaging of a material surface; to estimate the quantitatively characteristics of a material surface; to observe the imaging interferential pictures both in the white and in the monochromatic light; to carry out the investigation of blood cells, microbes and biological macromolecules profiles. The method allows restore 3D topography of a material surface in a real time regime. The information about the material surface at partially coherent light is contained in the visibility of interferential strips. The distinctive features of device are: the non-contact electromagnetic loader; the differential size of depth of indenter introduction into the sample, that has allowed considerably reduce a rigidity of construction; a small weight and dimensions; job in a real time regime; low cost.

The paper presents an approach for measurements of corneal topography by use of a patent pending double path shearing interferometer (DPSI). Laser light reflected from the surface of the cornea is divided and directed to the inputs of two interferometers. The interferometers use lateral shearing of wavefronts in two orthogonal directions. A tilt of one of the mirrors in each interferometric setup perpendicularly to the lateral shear introduces parallel carrier frequency fringes at the output of each interferometer. There is orthogonal linear polarization of the laser light used in two DPSI. Two images of fringe patters are recorded by a high resolution digital camera. The obtained fringe patterns are used for phase difference reconstruction. The phase of the wavefront was reconstructed by use of algorithms for a large grid based on discrete integration. The in vivo method can also be used for tear film stability measurement, artificial tears and contact lens tests.