The feasibility of optoacoustic imaging was investigated for ophthalmologic application in the treatment of glaucoma. Difficulties in the treatment with laser cyclophotocoagulation are mainly due to uncertainties in the localization of the ciliary body. With laser optoacoustics it is possible to localize the position of the ciliary body on enucleated porcine and rabbit eyes. Additionally, the changes in the optical properties of the tissue induced by coagulation with a diode laser were observed.

We propose a new method of burn depth estimation based on the measurement of photoacoustic signal from the skin, where the acoustic waves originated from the light absorption by blood are detected with a piezoelectric transducer put on the skin surface. Because vascular occlusion takes place in the thermally-damaged tissue layer, the propagating time of the blood-originated signals would have the depth information of injury. To investigate the validity of the proposed diagnosis, experiment using rat burn model was performed. The results showed that deep burn (DB), deep dermal burn (DDB), and control (healthy skin) can be well differentiated by the photoacoustic signals. Quantitative information relating to the depth of injury can be also obtained from the signals.

Optoacoustic tomography combines advantages of pronounced optical contrast between different tissues and high resolution of ultrawide-band ultrasound imaging. Laser pulses may be effectively used to produce acoustic sources in tissue with enhanced optical absorption. Ultrasonic waves can propagate in biological tissue with minimal distortion and deliver diagnostic information to the surface of tissue, where they may be detected with temporal resolution by piezoelectric transducers. Current status of the optoacoustic tomography applied in early detection of cancerous lesions in the breast (utilizing forward mode) and in oral cavity (utilizing backward mode) is reviewed.

We report high speed (~ 470 frames/s) 3-D imaging using photorefractive holography with sources of diverse temporal and spatial coherence and discuss design considerations for real-world high bit-rate imaging systems. We also propose a new real-time optical sectioning technique based on structured illumination with photorefractive holography to detect fluorescence.

The scattering of polarized light from a multilayered scattering medium is investigated using Monte Carlo simulations. The polarization and spatial properties of the emerging light are used to perform tissue localization in order to extract the physical and optical properties of the layered medium. The polarization technique is enhanced using linearly and circularly polarized illumination to probe different depths. Absorption and layer thickness is varied and it is demonstrated that the determination of these values is aided by the inclusion of polarization information to allow localization of different volumes within the sample. Potential applications of these techniques are burn depth and melanoma thickness measurement.

Volume rendering is a typical technique for visualizing 3D Medical data such as CT data and MRI data. But its use has been limited by its high computational expense in terms of processing time and memory space. In this paper, wavelet compression using embedded quantization structure combined with a scan-converting volume rendering algorithm is utilized to achieve interactive visualization for medical imaging. To compress and decompress the wavelet coefficients efficiently, an improved SPIHT (Set Partitioning in Hierarchical Trees) algorithm is presented.

A novel nondestructive imaging technique, thermosonics, which combines ultrasonic/sonic excitation and advanced infrared imaging, will be described. In this paper, the authors will illuminate the physical principles underlining this technique, and demonstrate its applications to detection of cracks in teeth.

Optoacoustic pressure waves were generated by irradiating blood vessels embedded into calf cartilage with 5 ns long pulses from an optical parametric oscillator (OPO). A two dimensional pressure transducer consisting of a glass prism and a liquid layer was used to measure the laser-induced pressure waves. The pressure dependent changes of reflection at the prism-liquid interface were recorded with a time-gated CCD-camera. On the basis of the 2D pressure measurements the spatial distribution of the blood vessels was reconstructed using two different algorithms, one based on radial back projection and one using Fourier transformation. High lateral (100 micrometers ) and depth resolution (20 micrometers ) was achieved.

A scanning optoacoustic transducer was used to generate images of biological tissue in vivo. The transducer consisted of an optical fiber for delivery of laser pulses and an annular piezoelectric film. Optoacoustic waves were generated by irradiating the tissue with 5 ns long pulses from an optical parametric oscillator (OPO) which was tuned between 500 and 600 nm. The motorized scanner allowed to generate a 200x200 pixel image within 20 seconds. In images of human skin in vivo, certain structures such as the epidermis, blood capillaries and deeper blood vessels could be localized and identified by their spectral characteristics. From the spectral dependence of blood containing structures the oxygenation level of hemoglobin could be estimated.

Acousto-optic imaging in strongly light-scattering tissues seeks to reveal optical contrasts in these turbid media. Nevertheless, this technique happens to be also sensitive to their acoustic contrasts. We have built a new setup combining a dedicated echograph and an acousto-optic imager in a single apparatus. Thanks to this setup, we have studied ultrasound absorbent and light absorbent features embedded in several centimeter thick biological tissues, and we have compared for the first time the acoustic and acousto-optic signals recorded in the same configuration. We show that even though optical contrast is the ultimate goal of this technique, preliminary acoustic investigation of the tissue is necessary to interpret correctly acousto-optical signals.

Photo-acoustics (PA) is a technique, which can be used as the basis for non-invasive medical tomography. It is based on the absorption contrast between the biological target and the surrounding tissue and as a result of that does not suffer from strong light scattering. This fact makes PA suitable for imaging of the microvasculature in skin (532nm) or of deeper structures by using infrared light. In this paper, we present images of a vasculature cast, which was obtained by a Wistar rat and measurements on the absorption coefficient of Evans Blue.

We describe the development of a modular, multiwavelength, wideband intensity-modulated near infrared spectrometer (100MHz -1GHz) capable of simultaneous measurement of three parameters - the dc intensity, the ac intensity and the phase shift of light transmitted through tissue at a high sampling rate. The intended purpose of this instrument is the detection of fast dynamic changes in the reduced scattering coefficient of tissue due to cellular depolarization. The instrument requires sensitivity to small changes in optical pathlength and absorption in small volumes of tissue.

In this paper, an innovative ellipsometer is developed and applied to metrology of the biomolecular interaction on a protein biochip. Both the theory, optical and opto-mechanical configurations of this newly developed ellipsometer and methodologies adopted in system design to improve the system performance are presented. It will be shown that by measuring the ellipsometric parameters, the corresponding concentration variation in biochemical reaction can be calculated according to stoichiometry analysis. By applying the variable angle ellipsometry to analysis of a multi-layered sample, the thickness and concentration are resolved. It is believed that the newly developed ellipsometer biosensor is able to undertake an accurate measurement on biomedical interaction.

The photoplethysmographic signal (PPG) includes respiratory components seen as frequency modulation of the heart rate (respiratory sinus arrhythmia, RSA), amplitude modulation of the cardiac pulse, and respiratory induced intensity variations (RIIV) in the PPG baseline. The aim of this study was to evaluate the accuracy of these components in determining respiratory rate, and to combine the components in a neural network for improved accuracy. The primary goal is to design a PPG ventilation monitoring system. PPG signals were recorded from 15 healthy subjects. From these signals, the systolic waveform, diastolic waveform, respiratory sinus arrhythmia, pulse amplitude and RIIV were extracted. By using simple algorithms, the rates of false positive and false negative detection of breaths were calculated for each of the five components in a separate analysis. Furthermore, a simple neural network (NN) was tried out in a combined pattern recognition approach. In the separate analysis, the error rates (sum of false positives and false negatives) ranged from 9.7% (pulse amplitude) to 14.5% (systolic waveform). The corresponding value of the NN analysis was 9.5-9.6%.

Wavefront analysis as tool for quality control of optical systems is known for more than 100 years. With the availability of high quality Shack-Hartmann-Sensors at moderate cost, aberrometers became of interest for ophthalmic diagnostics. Customized corneal ablation guided by wavefront analysis of visual performance opens the opportunity for further improvement of the refractive surgical outcome.

Molecular interaction especially biorecognitive binding can be visualized by metal cluster enhanced fluorescence. Fluorescent molecules that are bound within the electromagnetic field of a layer of metal clusters exhibit a strong boost in excitation as well as emission. We present a study, using novel surface enhanced chips in glass-slide-format, their set up, the micro arraying onto the surface, and the hybridization of oligonucleotides on these chips. Compared to standard (glass slide) DNA chips, performance, fluorescent signals as well as signal to noise ratio were considerably higher.

We describe a new approach for the parallel reading of the dynamical response of micromechanical oscillators in array using an interferential imaging method coupled to a multichannel lock-in detection. The mechanical responses and the resonance frequencies of each oscillator are deduced from the images of their oscillation amplitude and phase versus the excitation frequency. The goal is the detection of femtogram mass changes through the measurement of induced resonance frequency changes between loaded oscillators and reference oscillators. A measurement of the phase change for a frequency close to the resonance frequency f is a sensitive and reliable method to determine the frequency shift (Delta) f. In this study bare and gold-covered SiO₂ cantilevers have been used as oscillators and a phase measurement sensitivity of 10^-3 rd has been achieved. Such a value is equivalent to a sensor mass change sensitivity better than 100 femtograms. The fields of application extend from DNA microchips to environmental sensors.

The reaction of bone cells after mechanical stimulation is a key issue in understanding the origins of osteoporosis. We investigate mechanical stimulation of osteoblasts and their reaction with a new combination of an atomic force apparatus with a fluorescence microscope. First measurements on the mechanically induced calcium response of osteoblasts are presented. The average threshold force for stimulation is 300nN and the dynamics of the calcium response is in the several tens of seconds range.

We report an experimental study of the trapping efficiency of an optical tweezers system acting on spherical polystyrene particles in water solution. As force calibration method we used the viscous drag exerted by fluid flow. A parametric study of the efficiency of the trap was made as a function of bead diameter and objective NA. Optical tweezers were also characterized in terms of the optical potential well by measuring the displacement of trapped particles undergone to a viscous drag for fluid flow below the critical velocity. Trap stiffness was determined for particle size of 14.9 micrometers at different laser power.

A mathematical model for understanding near-field Mie scattering, as used in optical trap nanomery for single molecule detection, is developed. Both perpendicular and parallel polarization states of incident electromagnetic waves have been considered. Simulations under different incident angles, and refractive indices of trapped particle have been investigated. Half-space signal strength is studied on the base of the calculated three-dimensional scattered electromagnetic field.

The advantages of measuring both the excitation spectrum and emission spectrum of living cells' fluorescence are reviewed together with interferometric methods. Mitochondria in yeast cells are described as examples of Biomedical methods, also including mammalian cells. Mitochondria in human hepatic cells, murine mast cells and human keratinocytes are shown using the vital stains DASPMI, Mitotracker Green and TMRE. An example in Biotechnology is the study of photosynthetic algae, used in the production of hydrogen.

Infrared thermography is used to reveal the establishment of Erwinia amylovora harpin-induced hypersensitive response (HR) in Nicotiana sylvestris leaves. We observed a decrease in temperature (1-2 degree(s)C) in the harpin infiltrated zone, correlated with an increase in stomatal opening, strongly suggesting that the temperature decrease is due to higher transpiration rate. IRT experiments were conducted in a laboratory environment and could be widely applied for genotype screening and monitoring drug effects.

Red blood cell damage (hemolysis) and thromboemblism are the main complications associated to the implantation of mechanical artificial heart valves. In the last decades a great number of in vitro studies have been conducted to improve the design and to understand the transvalvular flow patterns under steady state and pulsatile conditions. Steady state tests are useful to study the flow established upstream and downstream the valve prosthesis in the moment of the peak flow rate. In the present study, Particle Image Velocimetry (PIV) technique was employed to visualise the flow patterns in a pre-commercial model of bi-leaflet mechanical heart valve prosthesis in a steady state flow. PIV technique and a convenient test rig have provided good conditions to investigate the whole flowfield upstream and downstream the valve.

A method of flow direction and velocity determination using statistical properties of dynamic speckles is proposed. Two point detection of scattered light intensity fluctuations allows for slow flows velocity measuring and flow direction determination without incident beam frequency shifting and with using one focused incident beam. The space-time correlation functions estimated for two position of the incident beam waist allows for the flow space localization and the absolute flow velocity measuring. The described method has the principal advantages for the bioflow investigations in comparison of the traditional laser Doppler velocimetry.

The lymph flow diagnostics in microvessels of rat mesentery were performed using light biomicroscopy, speckle- interferometry and spectroscopy. By light microscopy method we have got the dynamic of microvessels images in real time and registered phasic contractions and valve function of lymphatics, lymph and blood flow. The mean velocity of lymph flow was the highest at the moderate number of lymphocytes in flow. We had found the close links between phasic contractions, valve activity and lymph flow intensity. The high-resolution speckle-microscopy quickly gives much information about average lymph flow velocity, but only the relative value of velocity can be estimated. The phasic contractions cause the changes of the speckle signals and led to the modification of lymph flow in microvessels. The reflectance spectra characterize functional state of lymphatics and lymph flow in microvessels.

Measurements have been carried out using a pulsed laser-Doppler setup. The main advantage of pulsing a laser-diode is that much higher peak powers can be used, allowing a larger source-detector separation, resulting in a larger penetration depth. The method enables e.g. monitoring of cerebral perfusion as well as monitoring perfusion through organs (e.g. kidney).

An automatic device for high-temporal resolution of the process of erythrocytes sedimentation in blood was designed. The position of the boundary between red blood and plasma is registered each 30 sec in several pipettes simultaneously with +/- 10 mkm precision. Data are processed by a PC and presented as velocity-time curves (ESR-grams) and the curves describing time evolution of the boundary position. ESR-grams demonstrate non-monotonous character of erythrocytes sedimentation in blood. Blood of particular donor being in a stable physiological state taken on different days is characterized by similar ESR-grams. Pathological deviations from a normal physiological state are reflected in the shortening of duration of each process stage and increasing of average sedimentation rate. Intravenous infusion of some medical preparations may lead either to improving (prolonging of macrokinetic stages, decreasing of sedimentation rate), or to worsening of studied parameters depending on an individual. The low extent of blood dilution with saline in vitro lead as a rule to decreasing of sedimentation rate and improving of microkinetic parameters of the process. Adding of highly diluted hydrogen peroxide to blood samples of patients resulted in the improving of sedimentation kinetics. ESR-graphy may widen opportunities of practical medicine in diagnostics, prognostics and drug therapy.

We report a technique to estimate eye aberrations, based mainly on the subjective crossed-cylinder method. In order to obtain accurate coordinates of cross sections of the aberration distorted grid image on the retinal plane, needed in subjective methods, fusion of two images is used. The image seen by the eye under investigation is fused by the patient with a similar grid generated and reshaped in the appropriate way on the computer screen. The computer simulated image is viewed either by the second eye (in order to avoid eye rivalry and suppression processes, that are typical for such conditions, stimuli for both eyes are discontinuous and are displayed sequentially with a frequency of 50 Hz) or by the eye under investigation using an optical prism bypass.

In the present study the characteristics of lymph microcirculation are investigated. The lymph microcirculation was studied on small intestine mesentery during N^G=nitro=L-arginine (L-NNA) application on intact microvessels and after stress. The direct measurement of lymph flow velocity (parameter V) in individual microvessels was based on the technique of light intravital videomicroscopy. The first spectral moments of Doppler signal characterizing the mean velocities of lymph flow in microvessels (parameters M₁) were measured by the laser- speckle method. Simultaneously, diameters of lymph microvessels as well as parameters of phasic contractions and valve functioning were registered.

We present a useful tool for manipulating biological samples in microscopy. Cells and cell organelles can be trapped, moved and stretched with a combination of optical tweezers and an optical trap consisting of two opposing single mode optical fibers. Experiments demonstrate trapping and manipulation of micro-beads, and even mechanical deformation of blood cells with the system.

A model of human eye for experiments in vision research has been developed using PLZT ceramics. This artificial eye allows to simulate light scattering caused by cataract in the eye lens. Light scattering of a composite eye lens of the model depends on the electric field applied to a transparent electrooptic PLZT ceramics plate that is attached directly to the lens. The image degradation in such a model eye at various degrees of scattering is studied observing and recording the contrast of images on the retinal plane created by standard test objects with different spatial frequency or by a He-Ne laser source passing a diffractive transparent placed before the eye.

We investigate the potential of THz imaging for the examination of histo-pathological samples. Data obtained on a pig larynx and on a human liver containing cancerous tissue are presented. Different types of tissue are clearly resolved due to their distinct spectral absorption characteristics or due to a density dependent THz transmission.

This paper describes the optical system Svision including the attachment to PC's monitor and software for preparation and demonstration of stereoscopic images. This software-hardware complex provides possibility to demonstrate 3D stereoscopic objects on the kinescope screen of usual PC's monitor, such objects are interactively controlled by user. Advantages of system Svision over analogues are the following: spectators do not need individual hardware for viewing, there are no need in rework of computer, production of attachments is simple and does not require unique techniques. The complex is used for processing and display of data measured by means of scanning-probe microscope for analysis of complicated 3D objects and also for precision measurement schemes.

The vast majority information about cells and cell organellae structure were obtained by means of transmission electron microscopy investigation of cells serial thin sections. However often it is very difficult to derive information about 3-D structure of specimen from such electron micrographs. A new program restoring 3-D image of cells from the serial thin sections micrographs have been developed in our lab. The program makes it possible to visualize a 3-D image of cell and obtain image of inner cell structure in arbitrary plane. The plague bacteria and anthrax cells with spore were visualized with resolution about 70 nm by means of the program.

Transmission electron microscopy investigation of thin sections remains the major method of cells inner structure study with high resolution. However, the present-day technique of cells preparation make it impossible to study a number of biological samples, such as very small quantity of lymph cells of little insects (spiders, fleas, etc.). A new technique of cells preparation has been developed in our lab, which allow to obtain a thin sections of ultra small quantity of cells (less then 100). Structure of lymph cells of flea was investigated by the technique.

Optical methods represent the most promising techniques to perform non-invasive glucose detection. Glucose concentration in the aqueous humor closely mimics glucose levels in the blood and therefore non-invasive optical measurement of glucose can be performed by an optical beam crossing the eye anterior chamber. We propose a polarimetric method that exploits the Brewster-reflection of circularly polarized light on the lens of the eye. After reflection, the resulting linearly polarized light is subject to rotation by the glucose in the aqueous humor and thus carries the concentration information. A preliminary experimental setup, using glucose samples in a beaker, was realized and investigated.

Dynamic light scattering (DLS) and autofluorescence (AF) are non-invasive diagnostic techniques that can monitor changes at the molecular level in ocular tissues. In the present study, we demonstrate as simultaneous measurements of autofluorescence and dynamic light scattering on the corneal tissues can be performed using a novel specifically designed instrument. The integrated instrument takes advantage of the singular techniques by improving the measurement quality and the reliability of the diagnosis. Preliminary tests on volunteers show promise in relation to possible use in the clinical practice.

Laser induced phase transition in the water surrounding absorbing nanoparticle results in dramatic enhancement of the thermoacoustic efficiency and excitation of high- amplitude pressure waves. Feasibility study was performed in tissue phantoms. Experiments supported with theoretical model demonstrated possibility to increase the efficiency of optoacoustic generation in tissue up to two orders of magnitude by application of absorbing carbon and gold nanoparticles.