A beam-homogenizing device consisting of a short tip of a silver-halide infrared fiber removes the effect of low-order multimode generated by bending of hollow guides. A series of experiments employing a CO₂ laser shows that the solid fiber functions as a homogenizer with a small insertion loss of 0.2 dB.

The applications of ultraviolet lasers in medicine and surgery are expected to produce new therapies since UV laser is strongly absorbed by lipids, proteins and nucleic acids. The suitable tools for the UV laser power delivery, however, have not been developed yet. In an effort to make efficient delivery of UV laser, we have proposed hollow light guide which consists of an aluminum-phosphor bronze reflector and a teflon E-type rail spacer. The delivery characteristics of the hollow light guide have been investigated using the ArF and KrF excimer lasers. In case of the KrF laser, the transmittance and delivery energy reached 77%/m and 110 mJ/pulse, respectively. In the ArF laser, the transmittance and delivery energy were obtained to be 56%/m and 40 mJ/pulse, respectively. It is known that 193 nm radiation by the ArF laser are absorbed by the air. Thus, the ArF laser beam delivery were examined in the helium gas. The transmittance and the delivery energy were obtained to be 72%/m and 50 mJ/pulse using helium-filled hollow light guide, which were greatly improved for comparison with the case of the air. We have also tried the quartz fiber with OH ion doped core. The effects of a lightly doped core with Cl and a clad with B-F on the laser transmittance have been investigated. In these result, the Cl was not good core dopant. The B and F were useful clad dopants for the excimer laser transmission.

Hollow waveguides for infrared radiation are suitable for high power radiation and large interval of wavelengths. This has enabled to begin its preparation for several practical applications in medicine which are already investigated. One of the types of these waveguides is made from plastic (teflon) tubes and several papers were published in this field. Although the Teflon waveguides have several important advantages (high flexibility and biological suitability) for application in medicine, there are also difficulties in achieving low attenuation (low radiation losses), of the transmitted radiation, which is limiting their applications. One of the main reasons of the large losses of the transmitted radiation through these waveguides is the relative large roughness of the internal wall of the tubes which produce scattering of the incident radiation. Several attempts to reduce the roughness have given only a limited improvement since the internal wall of the Teflon tube is not easy to polish (the needed average roughness is less than 10 nm). In previous papers we have reported first results obtained in developing a new type of hollow waveguide for infrared made from polyimide which is a type of plastic with high melting temperature and which can be prepared with very flat surface roughness, less than 10 nm. In this paper we shall present new results of a study made for developing this type of plastic hollow waveguide. The attenuation was reduced to values less than 1 dB. Data about the process of etching for decreasing the roughness of the internal wall of polyimide tube and new methods of deposition of high adhesive and minimal roughness of the Ag and AgI guiding layers will be presented. Results of measurements of attenuation as a function of bending radius, coupled power and time of transmitted radiation will be shown and discussed. New type of dependence of attenuation on bending due to the mechanical properties of the polyimide tubes will be shown and discussed.

Hollow glass waveguides are an attractive fiber delivery system for both the 3 micrometers Er:YAG and 10.6 micrometers CO₂ lasers. The losses for these waveguides are as low as 0.2 dB/m at CO₂ laser wavelengths for guides with a 700 micrometers bore. At the shorter wavelengths of the Er:YAG laser the losses are higher than those predicted theoretically. This is shown to be a result of surface roughness of the inner coatings. These hollow guides are found to have losses which change little with time or cyclic flexure. A new version of these guides made from polycarbonate tubing is described and the losses for these guides are shown to compare favorably with those for the glass guides.

The luminescence of silver bromide crystals doped with rare earth ions (Nd³⁺, Pr³⁺, and Er³⁺) was investigated in the visible and near infrared spectral ranges. The emission, excitation, and absorption spectra, as well as the kinetic parameter, were measured over a broad temperature range. The Judd-Ofelt analysis was applied to the rare-earth doped crystals, and transition rates, branching ratios, and quantum efficiencies were calculated. Good agreement between theory and experiment was obtained.

Theoretical modeling of strongly pumped doped silver halide fiber amplifiers is presented. This is an analytic part of an effort to introduce new lasing materials, composed of doped silver halides, in the near or mid IR region. The analysis is based on a rate equation formalism, for which experimental measurements of various optical properties of doped silver halide and crystals were applied as input parameters. The model includes solutions for both three- and four-level systems, such as Er³⁺ and Nd³⁺. Optimal range of fiber dimensions, doping materials and concentrations, and other optical properties are suggested in order to achieve significant amplification.

2 m-long and small-bore fluorocarbon polymer -coated silver hollow glass waveguides have been fabricated by using all liquid phase process and their transmission properties have been experimentally analyzed. The total straight transmission losses for the single-shot Er:YAG laser light were measured as about 0.4 dB and 1.0 dB for 2 m-long hollow waveguides with the inner diameters of 700 micrometers and 540 micrometers , respectively.

Results of the R+D works as well as technological trials aiming at conception and manufacturing of the light guide rods (applicators) for photon coagulators, applied for therapeutical treatment and surgery, have been presented. Such rods, due to their light guiding structure, enable effective guidance of the NIR radiation of a high energy directly to the treatment area. A method was worked out to convert specially matched glasses into the integrated light transmitting structures. The effect of a type and quality of the glass, light guides structure and their aperture onto the effectiveness of radiation power transmission was investigated. The first trials were carried out to apply new type of rods for laparoscope and gynecological treatments.

The preparation pure glasses, fiber's drawing and optical characterization of chalcogenide (As₂S₃, As₂Se₃) and chalcohalide (As-Se-(Br,I), Ge-Se-I, Te-Se-Br etc) are given. Their transfer properties are suitable for a laser delivery of Er:YAG, CO and CO₂ laser energy. For active optical fibers sulfide GeGaS and GeGaAsS glasses doped with Pr³⁺ ions were prepared and their optical and fluorescence properties are studied and offer perspection applications as the spectral fluorescence, the fluorescence lifetimes of ¹G₄ and the temporal fluorescence decay in a biomedical sensors.

The so-called photoacoustic technique combines optical properties, such as absorption and scattering, with acoustic properties, such as sound velocity and absorption, to monitor and measure the physical properties of materials. This paper comprises a theoretical study on the properties of acoustic pulses and a discussion on earlier theories presented in literature. It also describes and analyzes the results of simulation tests based on the Monte-Carlo method, undertaken to examine the effects that absorption and scattering co-efficients of two-layer media have on the shape of the acoustic transmitter. Finally, the theoretical results are corroborated with measurements using a CO₂ laser and a two-wavelength diode laser PA system, developed during the study.

The early evaluation of the visual status of human infants is of a critical importance. It is of utmost importance to the development of the child's visual system that she perceives clear, focused, retinal images. Furthermore if the refractive problems are not corrected in due time amblyopia may occur. Photorefraction is a non-invasive clinical tool rather convenient for application to this kind of population. A qualitative or semi-quantitative information about refractive errors, accommodation, strabismus, amblyogenic factors and some pathologies (cataracts) can the easily obtained. The photorefraction experimental setup we established using new technological breakthroughs on the fields of imaging devices, image processing and fiber optics, allows the implementation of both the isotropic and eccentric photorefraction approaches. Essentially both methods consist on delivering a light beam into the eyes. It is refracted by the ocular media, strikes the retina, focusing or not, reflects off and is collected by a camera. The system is formed by one CCD color camera and a light source. A beam splitter in front of the camera's objective allows coaxial illumination and observation. An optomechanical system also allows eccentric illumination. The light source is a flash type one and is synchronized with the camera's image acquisition. The camera's image is digitized displayed in real time. Image processing routines are applied for image's enhancement and feature extraction.

A new technique for direct monitoring of biochemical binding events of individual molecules was developed. Artificial gated ion channels in supported membranes of circular bolaamphiphilic lipids mixed with lipid phase modifiers were used to monitor the binding events of analyte molecules to the ion channel inducing a change of the ion concentration in a small sub membrane compartment. Ion flux or the ion concentration within the small compartment was determined electrochemically or by using fluorescent indicator dyes. Binding of the analyte to ligand modified peptide channels resulted in an on/off-response of the channel current due to channel closure or distortion. Trans-membrane permeability changes were quantified by applying a trans-membrane potential or a transient pulse of pH or ion concentration. Doubtless, the need for a direct more specific measurement in complex matrices leads to the increased interest in this form of miniaturized analytical device. Nevertheless most of the biosensors developed up to now use the biochemical processes of correlated bioanalytic assays. In bioanalytical assays where the analyte binds to an artificial membrane ligand a new strategy had to be developed. This paper presents new sensor devices using optical and electrochemical signal transduction. The biorecognitive interaction of an analyte at a ligand modified Bisgramicidin A ion channel results in a nearly digital on/off response of the channel current due to peptide channel closure or distortion. The current response of the sensor induced by analyte binding depends on an accurately positioned small ligand and on the binding of a large analyte molecule as e.g. an antibody. The trans-membrane leakage of membrane through membrane channels. Sodium and potassium ions as well as protons are widely spread in biological fluids. For this reason they are utilized as mobile species which are forced to move through the ion channels by an electric field or a concentration gradient. This gradient was induced either electrochemically or by ion concentration shift. The data presented show the optimization of the setup and first studies with this new device monitoring analyte gated ion channels in supported lipid membranes on sensor chips.

In many applications of Laser Doppler Velocimetry object velocity varies with time within some more or less wide range. Large variations present a problem for signal processing. This difficulty may be reduced in the proposed new Laser Doppler Velocimeter which utilize the periodic polyharmonic spatial probe field. The probe field is formed by the holographic technique employing the periodic wavefront modulator and the field-forming hologram. By proper selection of the parameters of these components, the probe field with pronounced high-order spatial harmonic content is obtained. This results in the presence of several Doppler frequency harmonics in the output signal, for the single value of object velocity. One of these harmonics is used for velocity determination. The choice of a particular harmonic depends on how well it fits into the frequency range of the instrument's electronics. If the object velocity becomes too small or too large, some other Doppler frequency harmonic which now fits better into the instrument frequency range is used for further processing and velocity determination. Experimentally, the multi-harmonic probe field was obtained and the effect of its spatial structure on Doppler signal composition was studied.

Amplitude equations are obtained for the optical fiber cantilever than periodical force acts for excitation of vibrations. Two cases are considered which correspond to one or two clamped cantilever's ends. Fiber optical cantilevers from different fiber's materials are considered to get high sensitivity. Grating's type registration of the fiber cantilever vibrations are discussed.

The optoelectronic biosensor, based on Surface Plasmon Resonance (SPR) for detection of photosynthesis-inhibiting herbicides in aqueous solutions is presented. The pesticide capability to replace plastoquinone from its complex with D1 protein is used for the detection. This replacement reaction results in the changes of the optical characteristics of protein layer, immobilized on the gold surface. Monitoring of these changes with SPR-technique permit to determine 0.1 - 5.0 mkg/ml herbicide in solution within one hour.

NIR spectroscopy allows monitoring of muscle oxygenation and perfusion during contraction. The knowledge of modifications of blood characteristics in body tissues has relevant clinical interest. A compact and reliable device, which makes use of two laser diodes at 750 and 810 nm coupled with the skin surface through optical fibers, was tested. NIR and surface EMG signals during isokinetic contractions were studied. A set of parameters was analyzed in order to obtain information about metabolic modifications during muscle fatigue.

In a first part we report on a Ti:sapphire pumped Er³⁺:YLF laser. The dopant concentration and the polarization of the pump beam is optimized. The highest slope efficiency is obtained with the polarization of the pump beam parallel to the c-axis and a dopant concentration of 20 at. %Erbium. Slope efficiencies up to 50% are achieved. This value clearly exceeds the Stokes limit of 35%. Further, we report on an Er³⁺:BYF laser pumped with two polarization-coupled diode lasers. The dependence of slope efficiency on the reflectance of the resonator mirrors, on the focus of the pump light, and on the resonator length is investigated. The best slope efficiency of (tau) equals 24% is obtained for a nearly hemiconcentric resonator with a reflectance of R_in(DOT)R_out equals 97.6% and a pump beam focused with a lens of f equals 20 mm. To obtain a higher pump power, we investigate the coupling of sixteen diode lasers, each one operated to emit a maximum power of 800 mw. The diode laser emission is collimated and then focused using aspherical lenses. The point spread function of this system is investigated. Laser action in a longitudinally pumped Er³⁺:YLF is already achieved using only one single diode laser.

The set of diffractive optical elements for CO₂ and Nd- Yag lasers was theoretically calculated, fabricated by microlithographic technology and experimentally tested. It is shown that the laser systems for therapy, surgery and welding gain from advanced capabilities of the DOEs: uniform focal-spot intensity, simultaneous formation of focal line contours, sharp and multiple-spot focusing, dual-wavelength achromatization, miniaturization. Novel multifocal diffractive contact lenses are elaborated based on diffractive microrelief considerations, nonparaxial variant of diffraction integral on curved surface and computer simulations of intensity distribution on eye retina. Tri- focal diffractive contact lenses that were diamond-turned on rigid and soft materials successfully passed tests.

Thin-film luminescent concentrators were studied as novel position sensitive optoelectronic devices. The concentrators were designed as a 16 X 16 lines grid or as a planar structure of 16 X 16 channels along two coordinates. Minimal distance between two lines in grid concentrators was 5 mm. Each line or channel was coupled to silicone photodiode which was connected via analog board and C/D converter to computer. 100-W halogen lamp was projected into concentrators via optical system. Software was developed to determine the center of the light spot and to show its border. Position of the center of the light source was determined with accuracy 0.5 mm. Processing time for this operation was less than 1 ms. The concentrators were able to detect the position of the light source under conditions which were similar to peripheral human vision. Such position sensitive optoelectronics device are promising to build smaller scale integrated device which could be perform of full detection and preprocessing operation in artificial human retina.

We have studied a prototype of human retina which is based on a round thin-film photoluminescent concentrator coupled at its edge to the circular Si-photodiodes. This passive integrated optoelectronic device can perform most important function of peripheral human vision: determination of position of the light source and motion detection. For 12-mm radius film we have got a spatial resolution 13 micrometers in the linear range +/- 5 mm. By stacking several films each with a different absorption characteristic it is possible to realize color sensitive element and, therefore, to perform full functions of human retina.

A telemeter hold by the hand of a blind person measures the distance to the obstacle encountered by its laser beam (1 mW at 670 nm). A microprocessor realizes a correspondence between the distance and a musical note sent to an auricular. The blind person directs the beam thanks to his proprioception. The most important information is not the absolute distance but the musical melody corresponding to the profile of the environment. Combining musical perception and proprioception the blind acquires the form of the obstacles and his position relative to them. Method of learning is in progress.

Instruments based on photon counting in the visible part of the spectrum with subsequent signal autocorrelation of the light intensity fluctuation are widely used for the characterization of clear media, but are performance limited if multiple scattering samples or particle suspensions with an inherent diffusion limitation are probed. These systems are classified as turbid media. We give advanced approaches as to how multiple scattering systems predominantly existing in industry can be examined, in order to resolve the sizes of suspended scattering centers. Latex particles and emulsions were used as models. Monte Carlo calculations of the light transport mechanisms in turbid media were performed and compared with measurements. A dynamic light scattering instrument was used to perform measurements on highly concentrated and turbid samples. For example, with particle standards of 83 nm, a size of 85 nm +/- 5.8 nm (n equals 10) was obtained and particles with a size of 895 nm were measured to be 895 nm +/- 9.1 nm (n equals 10). The influence of multiple scattering on the autocorrelation function was both measured and calculated. We have shown that our calculations are in good agreement with the test results obtained and it was found that our miniaturized instrument is a valuable tool to measure particle sizes in turbid media.

In this paper a novel low-coherence interferometer using a self-mixing super luminescent diode is described. The optical scheme presented uses the photodiode on the back- face of a commercial super luminescent diode to detect the interference signal. The low-coherence interferometer, here proposed, for the first time sums up a Fizeau interferometer and s

The construction principles of `calibration-free' optoelectronic systems of biomedical diagnostics are considered. This systems eliminate as much as possible methodical errors caused by the changes of instrumental constants of emitting-receiving and recording blocks, by the pollution of optical surfaces, by the state of used cuvettes, etc. The evaluation of accuracy of proposed methods is given.

For investigation of influence of pulsatile blood volume fluctuations on the saturation measurements more than 10 thousand pulse wave signals for 5 subjects in 20 experiments were measured and the modulation (M), modulation ratio (MR) of the red and infrared light signals, cardiocycle duration (T), correlation (C) between the red and infrared light were determined. There were C > 0.97, for all pulse wave signals, C > 0.995 for 90% of them. Changes of the M within an experiment were from 10 to 100 percents while the MR changed from 1 to 20 percents. The periodical changes of the M, MR, and T which one can associate with a breath rhythm were registered. The M and T changed synchronously. Obtained high C between red and infrared signals, when M spontaneously changed significantly, gives basis to suppose that pulsatile blood volume fluctuation does not effect on MR and arterial blood saturation (SaO₂) measured. One could suppose that the periodical changes of MR might be caused by variation of the blood saturation on different phase of breathing process.

The full polarization elements parameter optimization is conducted to minimize the determination error of Mueller matrix elements and to accelerate the measurement. The optimal retarders rotating frequency ratio is found. Expressions for the Mueller matrix elements is given in terms of components of the signal Fourier decomposition for the dynamic Muller-polarimeter (which scheme was proposed by R. Azzam in 1978) with arbitrary parameters. Muller- polarimeter with optimal parameters is shown to have the measurement error in 1.7 times less than Mueller-polarimeter with parameter chosen in traditional manner. The correspondent computer simulation is conducted to confirm theoretical study.

Flexible fluorocarbon polymer-coated silver hollow glass waveguides, devised for the delivery of 3.0 micrometers radiation, were evaluated sing a plasma cathode HF laser emitting at 2.78 micrometers , in a 180 ns duration, at a 1 Hz repetition rate. A multimode beam of 10 mrad divergence at FWHM, was focused into the 700 micrometers diameter, 986 mm long waveguide and was transmitted through it under straight and various bent conditions. The straight transmission loss was found to be 0.9 dB/m, while the bent transmission losses varied from 2.0 dB/m (90 degree(s) bent -35 cm bending radius) to 2.4 dB/m (180 degree(s) bent -10 cm bending radius), for the range of measurements attempted. Transmission as a function of the laser energy input was also measured. Losses increased from 1.5 dB/m at 3 mJoules to 7.0 dB/m at 20 mJoules laser input. These attenuation characteristics at the wavelength of 2.78 micrometers make these waveguides very promising for pulsed radiation and tissue interactions in in vitro and in vivo trials.

Dynamic light scattering (DLS), video microscopic and ultra- microscopic observation were simultaneously employed for screening of protein crystal growth in the vapor diffusion regime. The setup, consisting of a modified microscope equipped with a laser sheet (darkfield) illumination for ultra-microscopy, allows the visualization of clusters in the nanometer range as well as of macroscopic crystals parallel with the DLS measurements. The results of microscopic and ultra-microscopic observations, the DLS autocorrelation functions and the resulting relaxation time distributions for the standard protein lysozyme are presented. The special conditions for dynamic light scattering measurements in the pre and post crystallization phase with samples situated in small droplets and covered by a standard crystallization plate are discussed.

The main applications of laser to different fields of medicine and biology are reviewed and compared by a biologist. The good output of high quality papers in the biomedical field effectively contrasts with a scarce popularity of lasers in biological laboratory. In fact, a search in the Medlars database, confirmed that the use of lasers in a strict biological context is very limited or confined to few oriented laboratories. The `common' biologist does not have a precise point of view. In this perspective, the biologist would propose the following approach: (1) promote training programs to create new professional figures; (2) encourage the formation of scientific and technological research networks between biologists and laser specialists.

In order to perform long-term studies up to one week on a preselected single cell after micromanipulation (e.g. UVA and NIR microbeam exposure) in comparison with non-treated neighbor cells (control cells) we applied a variety of single cell diagnostic techniques and developed a special comet assay for single preselected cells. For that purpose adherent cells were grown in low concentrations and maintained in special sterile centimeter-sized glass cell chambers. After preselection, a single cell was marked by means of diamond-produced circles on the outer cell chamber window. During exposure to microbeams, NADH-attributed autofluorescence of the chosen cell was detected by fluorescence imaging and spectroscopy. In addition, cell morphology was video-monitored (formation of pseudopodia, membrane blebbing,...). Maintaining the microchamber in the incubator, the irradiated cell was examined 24 h later for cell division (clone formation) and modifications in autofluorescence and morphology (including daughter cells). In the case that no division occurred the vitality of the light-exposed cell and of the control cells were probed by intranuclear propidium iodide accumulation. After fixation, either electron microscopy or single cell gel electrophoresis (comet assay) was performed. To monitor comet formation indicating photoinduced DNA damage in the preselected single cell in comparison with the non-exposed neighbor cells the chamber was filled with low-melting gel and lysis solution and exposed to an electric field. In contrast to the conventional comet assay, where only randomly chosen cells of a suspension are investigated, the novel optimized electrophoresis technique should enhance the possibilities of DNA damage detection to a true single (preselected) cell level. The single cell techniques applied to UVA microexposed Chinese hamster ovary cells (364 nm, 1 mW, 3.5 W/cm²) revealed significant cell damage for J/cm² fluences such as modifications of intracellular redox state, impaired cell division, formation of giant cells and cell shrinking, swelling of mitochondria and loss of cristae as well as DNA damage.

Recognition molecules play important regulatory roles during pattern formation of the nervous system. We here show that optical tweezers can successfully be used to functionally and quantitatively compare neuron interactions with glycoproteins of the extracellular matrix. We measured the forces of interactions between tenascin-C, laminin-1 and fibronectin coated polystyrol beads and the cell membranes of different nervous cell-types. This was achieved by applying the optical tweezers as picotensometer to pull the adhering beads with varying axial forces. To this aim, the minimal laser powers for capturing polystyrene beads in different solutions were measured. With the corresponding Archimedes Forces the acting forces in the range of pN were calculated. The glycoproteins showed significantly different behavior. Specific binding was shown by antibody experiments, in which the binding forces were significantly reduced for the corresponding antigens but not for the other glycoproteins. Together with experiments concerning the moving within the plane of the membrane and the cleavage with glycosyl-phosphatidyl-inositol-anchors specific phospholipase-C we suggest that these glycoproteins interact with neurons by different mechanisms.

The fluorescence-based detection of single dye labeled protein molecules at interfaces is presented. Glass substrates with covalent immobilized antibodies serve for capturing matching antigens from volume concentrations between 10^-12 and 10^-17 mol/l. The unspecific binding at the interface has been reduced to a level down to 0.1% of the maximum signal level. At concentrations lower than 10^-13 mol/l we observe single antibody-antigen complexes at the surface. We developed a scanning method for counting single antibody- antigen complexes. The counting results are used for calibrating the volume concentration dependency. AT the present stage, the detection limit of this molecule counting process is of the order of 10^-17 mol/l, and the dynamic range detectable antigen concentration is more than 8 orders of magnitude, without reaching a limiting value. The instrumental set-up is similar to that of a confocal microscope. A diode laser is used as an excitation source. As an first application in early-stage-diagnostics, we investigated the detection of a single cardiac-actin molecule in human plasma.

In cell and molecular biology, single-beam gradient force optical traps (`laser tweezers') are mainly used as 3D micromanipulation tools, e.g. in controlled cell transport. Otherwise, near infrared (NIR) laser tweezers may act as useful diagnostic tools. They can be used (1) for sensitive measurements on highly-motile cells or organelles by sample confinement within the focal volume, (2) as force transducer, and (3) as linear and nonlinear excitation source. In the case of cells with one-photon NIR absorbers, such as erythrocytes, linear NIR excitation of hemoglobin can result in photothermal hemolysis. In addition, two- photon excitation of a variety of endogenous cellular absorbers, such as NAD(P)H, flavin and porphyrins, occurs de to the high photon flux densities in optical traps. Two- photon NIR excited visible fluorescence of endogenous as well as within a sub-femtoliter focal volume allows a novel nonlinear fluorescence diagnostics of cells and biomolecules.

In biological dosimetry after radiation or chemical exposure, it has been well established to estimate exposure doses from the relative rate of aberrant chromosomes, especially dicentric chromosomes in a given number of cells. For this purpose, dose-efficiency curves depending on laboratory parameters (e.g. preparation technique, analysis procedure etc.) have to be measured under standard conditions. For statistical reasons, a high number of chromosomes or cells, respectively, has to be evaluated. For a Chinese hamster cell line (CO60) as a typical model system in mutation research, a dose efficiency relation after H₂O₂/L-histidine treatment of the cells was determined using the Heidelberg slit-scan flow fluorometer. This technique has the advantage that several thousand chromosomes can be automatically analyzed in a very short time. As expected, for low doses of H₂O₂/L-histidine exposure, a nearly linear dependence of the relative number of dicentric chromosomes to the concentration of H₂O₂ was obtained. In order to correlate the relative number of dicentric chromosomes to the relative number of double strand breaks, the cells were analyzed by the technique of the neutral comet assay. The dose dependent `tail moment' obtained from the comet assay also showed a linear behavior. This confirmed the results obtained by slit-scan flow fluorometry. Furthermore, the linear dependence of the dose efficiency curve was well compatible to results obtained by visual counting by means of a fluorescence microscope. In this case chromosome 1 of the Chinese hamster cell line DON was specifically labelled by fluorescence in situ hybridization.

The precise magnetophoretic measurements of magnetic susceptibility of red blood cells and sorbent microparticles fulfilled with the video-camera observation and light scattering detection were applied for the identification of the cellular free radical excess under oxidative stress, paramagnetic ions changes and the immunospecific binding detection. The fast and sensitive assay allows to determine weak paramagnetic or diamagnetic shifts relatively surrounding solution connected with hematological and metabolic cellular disorders, external chemical influences by ions and organic molecules additions in range 10^-4 - 10^-6 M. The autoregistration of magnetophoresis facilitated the analysis of the functional states of cells and the macromolecular binding detection.

The kinetics of albumin absorption onto various solid surfaces was studied with the surface plasmon resonance technique. The following types of the samples were used in the absorption experiments: as-deposited gold layers, gold layers after oxidative washing, hydrophobic and hydrophilic plasma polymers. Absorption of the protein onto each of these surfaces was found to have some distinguishing features. The fastest kinetics and the maximum protein coverage were observed in the case of the gold layers without any pretreatment. By contrast, the absorption was almost completely suppressed in the case of the hydrophilic polymer overlayer. In addition, the effects and poly(ethylene glycol) or toluene added to the solutions were investigated. The presence of the toluene caused negligible changes in the absorption kinetics while the absorption was substantially suppressed in presence of poly(ethylene glycol). Possible mechanisms of nonspecific protein-surface interactions are analyzed in order to explain the observed differences in sorption behavior.

New laser crystals have been developed to convert near infrared laser light into a 3 micrometers laser beam. With this concept the 3 micrometers laser light is created directly at the position where the application occur, either inside the body or on the tissue surface. The problem of transmitting the 3 micrometers laser light through fibers consequently no longer exists. The laser emission is a transition of ⁵I₆ - ⁵I₇ of holmium ions in a BaYb₂F₈ crystal. Pumping with the Nd:YAG laser line of 1.12 micrometers leads to direct excitation of holmium ions from the ⁵I₈ niveau to the upper laser level. This direct pumping is more efficient than pumping of the Yb ion by 1.047 micrometers . With this converter crystal very small systems can be realized for endoscopic applications or for handheld lasers. The advantages of this converter crystal are high conversion efficiency of 25%, low dependence of conversion efficiency versus Ho and Yb concentrations, pump density and pump geometry. Pulsed systems for laser ablation of soft and hard tissue and also cw-applications of the 3 micrometers radiation are possible.

At present wide-spread of cancer and high mortality caused by the disease (350000 people per year in Russia) make scientists search for new laboratory tests to diagnose malignant tumors. Thus, diagnostics of pre-tumor states when effective therapy is still possible is considered to be the most important problem. Diagnostics of stomach, lung and breast cancer is a particularly burning issue because of the difficulties of their early identification. In these cases precise monitoring seems possible only by using of complicated instrumental testing methods. All up—to—date paraclinic diagnostic methods (except the histologic one) may give considerable percentage of errors [1 , 2, 3]. Even the histologic method does not ensure full accuracy [4] due to a number ofsubjective and objective reasons. So, the need to develop a new methodology of pre—morphological diagnostics allowing to solve such an important problem as the character ofpathologic process identification is obvious. Thus, constantly increasing interest in optic methods of cancer diagnostics is understandable. First of all, it is caused by high sensitivity of these methods, possibility to examine tissue with minimal invasion through fiber-optic probes and harmlessness of probing radiation for human organism. One of the most precise researching methods in the given field is spectral analysis, in particular optical spectroscopy which allows to obtain considerable volume of significant information at investigation of biological object including human malignant tissue.