A detection system for capillary electroseparation methods based on fluorescence imaging has been developed. In capillary electrophoresis (CE) the detection unit is normally placed near the outlet part of the fused silica column where a window is opened in the coating and the fluorescence is recorded over a short distance to maintain a high resolution. Our method employs fluorescence imaging of the whole column during separation of various samples. The column is positioned in a straight holder and the outer protective coating of the column is removed to get optical access to the sample. An excimer/dye laser is used for excitation of the sample and the fluorescence is recorded with an image-intensified CCD detector and displayed in real-time. The CCD detector is read out with a rate of about 5 frames per second and the corresponding full fluorescence line profiles along the column are displayed. Thus, full electropherogram are displayed showing the propagation and gradual separation of the sample fractions. The main advantage of this method is that parameters such as sample concentrations, diffusion, wall interaction and sample-to-sample interaction can be studied in real-time over the full length of the column, which is crucial for efficient system optimization. Among several applications, isoelectric focusing, isotachophoresis and enzyme-substrate interactions can be mentioned. Methods for increasing the collection efficiency, such as fiber optic arrays, have been investigated as well as different methods for computer-assisted signal integration and filtering. A fiber array consisting of 500 optical quartz fibers has been constructed that gives a substantial improvement of the optical collection efficiency.

The development of three-dimensional automotive devices (micro-robots) for applications in analytical instrumentation, clinical chemical diagnostics and advanced laser optics, depends strongly on the ability of such a device: firstly to be positioned with high accuracy, reliability, and automatically, by means of user friendly interface techniques; secondly to be compact; and thirdly to operate under vacuum conditions, free of most of the problems connected with conventional micropositioners using stepping-motor gear techniques. The objective of this paper is to develop and construct a mechanically compact computer-based micropositioning system for coordinated motion in the X-Y-Z directions with: (1) a positioning accuracy of less than 1 micrometer, (the accuracy of the end-position of the system is controlled by a hard/software assembly using a self-constructed optical encoder); (2) a heat-free propulsion mechanism for vacuum operation; and (3) synchronized X-Y motion.

The potential of optical measurement techniques in the near infrared spectral range becomes increasingly recognized. Continuous wave laser reflectometry is a non-invasive and sensitive method to determine perfusion and oxygenation variations of a specific organ in-vivo. The knowledge of physiological and pathological changes of blood characteristics in body tissues has relevant clinical interest. The improvements of optical and electronic devices offer new possibilities to design reliable and precise instruments to satisfy medical users demand. The results of a collaboration between instrumental designer and physicians are presented. A new method for measuring skeletal muscle oxygenation during exercise and evaluating rehabilitation effects was developed. Two laser diodes generate the wavelengths to select oxygenated and deoxygenated hemoglobin and a fiber optic probe connects the instrument to the patient.

High sensitive CO gas analyzer based on tunable diode laser (TDL) was used as a real time monitor of endogenous carbon monoxide in a set of breath physiology experiments. The measurements of the CO content dynamics in exhaled air with 10 ppb sensitivity were attended with detection of carbon dioxide and O₂ in breath, lung ventilation parameters, heart rate and blood analysis using conventional techniques. Temporal variations of endogenous CO in human breath caused by hyperoxia, hypoxia, hyperventilation and sport loading were first studied in real time. Scattering of the CO variation time constants was observed for different tested persons. Possible reasons for this scattering related with the organisms' physiology peculiarities are discussed.

The current work was undertaken to develop optical methods for the controlled preparation of gold sols and conjugates with biospecific macromolecules. The extinction spectra of sols with the particle size and axial ratio polydispersity were calculated using Mie's theory, the T-matrix method, and various experimental sets of the bulk gold optical constants modified with regard to size-limiting effects. It was shown that the most generalized model including the size dependence of the imaginary part of the dielectric permeability and the size and shape polydispersity gave good agreement with the experimental extinction spectra for 5-, 10-, 24-, and 40-nm sols, as well as with the size dependence of the position and value of the extinction peak. Electron-microscopic and spectral measurements yielded calibration curves for efficient spectrophotometric control over the particle size and for estimation of the amount of restorer essential for the preparation of particles of a given size. The stabilizing concentrations and the extinction spectra of colloidal gold-ovomucoid conjugates were measured. A simplest two- layered spherical model was employed to elucidate basic changes in sol spectra after conjugation with specific biomacromolecules and to draw some conclusions about the conjugate shell structure.

This paper presents a characterization of a biocompatible, PEG-DA based photopolymer, using a holographic method. This technique allows quick and simple measurement of polymerization time. A correlation of the optical method with gel fraction is presented. The dependence of polymerization time on irradiation intensity and photosensitizer concentration is discussed. A range of photosensitizer concentration giving fully polymerized hydrogels is demonstrated, and an optimal concentration is found. The use of different photosensitizers is assessed in order to develop new photopolymers for biomedical applications.

Emission from a single mode 100 mW laser diode at 850 nm is used for realizing optical tweezers: the laser beam is introduced into a microscope and focused by the objective into the object plane. Injection of the beam into a 40X microscope objective has been studied and the position and the size of the waist measured. The trap performance was studied as a function of the dimensions of the trapped particles. Trapping of polystyrene latex spheres of different size (from 0.2 micrometer to 6 micrometer) was observed in different conditions of laser power and transverse velocity of the spheres. Biological objects, Tetraselmis, of large dimension (around 10 micrometer) were also studied. We demonstrate the existence of an optimal range of size of the particles to be trapped. Furthermore we measure minimum trapping power required for trapping and the maximum speed of the trapped objects as a function of the dimensions.

While lasers have found a wide field of application in the analysis of cells and biomolecules, their use in manipulation is less common. Now, new applications of lasers are emerging, which aim at cells and even molecules as biotechnological individuals: For example, in single cell gel electrophoresis individual cells are irradiated by UV laser pulses which cause radiation damage to DNA. When the whole cell is positioned in an electric field and the UV induced damages are converted into DNA strand breaks, the resulting DNA fragments are eluted out of the cell nucleus. Small fragments are running further than large ones. After staining of the DNA fragments, the cell has the appearance like a comet (therefore comet assay). The tail moment, a parameter quantifying the shape of the tail, gives information on the degree of DNA damage. The kinetics of DNA damage induction can be described by a type of exponential law with parameters which are related to radiation sensitivity of the DNA. A further emerging technique aims at DNA as a molecular individuum. One pivotal step for single molecule DNA analysis is single molecule handling. For that purpose, a DNA molecule is coupled to a micrometer sized polystyrene bead, either via an avidin-biotin bridge or, more specifically, by strand recognition, and labeled with fluorescence dyes such as DAPI. In order to visualize the dynamics of individual DNA molecules, highly sensitive video processing and single photon counting is required. Moving the polystyrene bead using optical tweezers, the molecule can be deformed, i.e., bent, turned or stretched. Using a laser microbeam, the same individual molecule can be cut into smaller portions.

We report on the development of a flow system integrated with a microscope that facilitates the simultaneous optical trapping and fluorescence excitation/detection of micron-sized samples that have been tagged with fluorescent probes. This system, when used in conjunction with nucleotide fluorescence labeling and DNA fragment cleavage procedures, offers the potential for the rapid sequencing of DNA fragments attached to microsphere 'handles.' Using a Nd:YAG laser (1064 nm) as the trapping beam, latex microspheres were stably trapped in a flow stream, where flow velocities in the range of 1 - 10 mm/s were achieved. Such flow velocities are commensurate with those required to stretch, and measure fluorescence from, DNA strands in high speed sequencing applications. High spatial resolution (approximately 1 micrometer) and high signal-to-noise ratios (greater than 10³) were achieved using a high N.A. objective lens for trapping and fluorescence detection within a confocal microscope geometry. In this system, samples could be displaced with the scanning laser trap by up to plus or minus 25 micrometers off the trapping beam axis in the sample plane while maintaining, at the same time, a large fluorescence detection efficiency. At a trapping depth of 20 micrometer below the chamber surface, a laser power of 100 mW was sufficient to hold a 2 micrometer diameter microsphere in a flow stream having a velocity of 1 mm/s while its fluorescence was measured. The results of a systematic study which investigates the effects of trapping efficiency, trapping depth, flow velocity, and tweezers holding time in a 500 micrometer by 500 micrometer flow microchamber system are reported. The application of this technique to the confinement and detection of fluorescence-labeled DNA nucleotides is also described.

A drug screening assay based on patterned cells was developed. The patterning was performed by detaching single lymphocytes with laser tweezers from a poly-ethylene oxide (PEO) surface and immobilizing them on a surface coated with Cell-Tak^R, a strong cellular adhesive. The detachment force of the cells from the PEO-surface was determined on a single cell base with the laser tweezers to be between 1.5 and 4.5 pN. Different lymphocyte classes were loaded with the fluorescent calcium indicator Fluo-3 and the pH indicator BCECF. Specific stimulation of the immobilized cells is monitored.

Evanescent wave sensors are an interesting tool for the fast detection of reactions between biomolecules. By using small and inexpensive diode lasers together with fluorescent dyes in the red spectral region, it was possible to construct a highly specific sensor. This was due to the use of the immobilization of receptor molecules via the Langmuir-Blodgett technique which enhances the specificity drastically. As a clinically relevant system an immunoassay of the tumor marker mucine was investigated. Mucine could be detected with a sandwich test using the antibody system BM-2/BM-7. In order to detect several analytes at one time, there are two possible ways: time-resolved detection using multiplex-dyes and the parallelization of the sensor by using several fibers simultaneously. A position-resolved evanescent wave sensor using a CCD camera is described.

For the production of recognition elements for evanescent wave immunosensors optical waveguides have to be coated with ultrathin stable antibody films. In the present work non amphiphilic alkylated cellulose and copolyglutamate films are tested as monolayer matrices for the antibody immobilization using the Langmuir-Blodgett technique. These films are transferred onto optical waveguides and serve as excellent matrices for the immobilization of antibodies in high density and specificity. In addition to the multi-step immobilization of immunoglobulin G(IgG) on photochemically crosslinked and oxidized polymer films, the direct one-step transfer of mixed antibody-polymer films is performed. Both planar waveguides and optical fibers are suitable substrates for the immobilization. The activity and specificity of immobilized antibodies is controlled by the enzyme-linked immunosorbent assay (ELISA) technique. As a result reduced non-specific interactions between antigens and the substrate surface are observed if cinnamoylbutyether-cellulose is used as the film matrix for the antibody immobilization. Using the evanescent wave senor (EWS) technology immunosensor assays are performed in order to determine both the non-specific adsorption of different coated polymethylmethacrylat (PMMA) fibers and the long-term stability of the antibody films. Specificities of one-step transferred IgG-cellulose films are drastically enhanced compared to IgG-copolyglutamate films. Cellulose IgG films are used in enzymatic sandwich assays using mucine as a clinical relevant antigen that is recognized by the antibodies BM2 and BM7. A mucine calibration measurement is recorded. So far the observed detection limit for mucine is about 8 ng/ml.

Information on the pH directly on surfaces of dental enamel is an important aspect in research on tooth decay. As an alternative to pH-electrodes our approach to the problem is the optical determination of pH by pH sensitive fluorescent dyes immobilized to tooth surfaces. In this study a model for measuring pH either on aminated cellulose substrates or on enamel (in vitro) with a fluorescein type dye is presented. The experimental realization is a fiber optic sensor with a nitrogen-pumped dye laser system and photodiode for the detection of the emitted fluorescence light. The surface pH values in the range between 4 and 7 were derived from the ratios of the excitation bands at 490 nm and 460 nm.

Slit-scan flow fluorometry is a laser-technological approach for accelerated screening and sorting of fluorescence labelled metaphase chromosomes. Details of the optics of the Heidelberg slit-scan sorter are presented. In a fluid stream the fluorescence labelled chromosomes rapidly pass one at a time by a scanning laser beam. The laser can be focused by a less complex optic consisting of only a few commercially available lenses. The laser intensity distribution around the focus was measured for 488 nm for two lens configurations. Although the light distribution obtained by such an optic is normally not aberration free, the requirements of a 'ribbonlike' shape in the center of the fluid stream can be fulfilled. Since the chromosomes are oriented perpendicularly to the laser beam by hydrodynamic focusing of the fluid stream, the fluorescence intensity along the chromosome axis can be measured time (equals spatially) resolved. According to their intensity profiles the chromosomes can be classified. Signal processing of the profiles can be performed in less than 600 microseconds, so that in the order of hundred chromosomes per second can be sorted out by a computer controlled electro-acoustic sorting unit. The final spatial resolution of a slit-scan flow sorter is not only affected by the focusing optics of the laser but also by the fluid stream, the detection optics and electronics, as well as by the computer analysis algorithm. Calculations often consider only the optics under ideal conditions. Here, a method is shown how to estimate the overall resolution of a slit-scan flow fluorometer experimentally. According to this criterion the resolution of the Heidelberg slit-scan sorter for 488 nm fluorescence excitation was estimated to be 2.4 micrometer in its basic optical configuration and 1.7 micrometer with additional correction of chromatic aberration effects.

We report non-invasive particle size measurements of polystyrene latex colloidal particles and bovine serum albumin (BSA) protein molecules suspended in tiny hanging fluid drops of 30 (mu) L volume using a newly designed fiber optic probe. The probe is based upon the principles of the technique of dynamic light scattering (DLS). The motivation for this work comes from growing protein crystals in outer space. Protein crystals have been grown previously in hanging drops in microgravity experiments on-board the space shuttle orbiter. However, obtaining quantitative information on nucleation and growth of the protein crystals in real time has always been a desired goal, but hitherto not achieved. Several protein researchers have shown interest in using DLS to monitor crystal growth process in a droplet, but elaborate instrumentation and optical alignment problems have made in-situ applications difficult. We demonstrate that such an experiment is now possible. Our system offers fast (5 seconds) determination of particle size, utilizes safe levels of very low laser power (less than or equal to 0.2 mW), a small scattering volume (approximately 2 multiplied by 10^-5 mm³) and high spatial coherence (beta) values. This is a major step forward when compared to currently available DLS systems.

The method of singular value decomposition is applied in the separation of the heart and the brain signals which are assumed linearly superimposed in a magnetoencephalographic recording. The signals have been obtained by a SQUID device operating in a separate epoch mode. Each signal is recorded by 37 channels and at the middle of its duration an auditory stimulus was heard by the subject. At the same time a 38th channel was recording the ECG signal. Averaging over all the epochs of the same channel aligned according to the auditory stimulus, and under the assumption that the brain and the heart signals are linearly superimposed, we eliminate any signal synchronous with the heart and retain any signal from the brain synchronous with the auditory stimulus. Aligning all the signals of each channel according to the heart, as defined by the QRS complex in the ECG, and averaging again, we eliminate any signal synchronous with the auditory signal and thus obtain a signal which consists from components aligned with the heart. We use these two 37 channel signals to define a subspace in the 37-dimensional space spanned by the signals recorded by the 37 channels in which the heart component is minimal and the brain component is maximal. The vector basis which is obtained this way defines the weights by which the single epoch signals that are recorded by the 37 channels can be linearly blended to form the underlying true brain signal.

An ultrasensitive detection method of CCK in aqueous solution was developed. This method utilizes intrinsic native fluorescence properties of CCK-molecules. A new delay-line multichannel plate photomultiplier (MCP PMT) was used to measure both time and wavelength resolved fluorescence properties simultaneously. Both CCK4 and CCK8 showed biexponential fluorescence decay. While the short lived fluorescence decay time components were rather similar, the long-lived components differed by about 1 ns. In the case of CCK8 the long-lived component was red-shifted by 30 nm. Based on these photophysical data an experimental setup for an ultrasensitive detection was developed. The lowest detection limit was achieved by investigating the fluorescence intensity within a time gate (gate duration 2 ns) in the fluorescence maximum. In combination with a confocal setup, using a Cassegrainean configuration, CCK could be detected up to 10^-12 M.

A new optical method based on measurements of kinetics of the oxygenation and deoxygenation of erythrocytes in various functional states is developed. The new optic device, modeling the conditions of the system of circulation of the blood in organisms and allowing us to measure continuously the absolute values of degree of blood saturation by oxygen in the process of oxygenation (deoxygenation) and change of the mean erythrocyte volume, was elaborated. The analysis of obtained kinetic curves allowed us to determine the amount of hemoglobin capable to reverse association with oxygen (the active hemoglobin) in investigated sample and discover the pathology forms of hemoglobin. The new method allows us to investigate nonspecific erythrocyte membrane permeability. The rates of oxygen and glucose penetration to erythrocytes in various functional states was measured. It was discovered that erythrocyte membrane permeability for oxygen periodically considerably changes in the process of oxygenation and deoxygenation of the blood. It was found that the functional state of erythrocyte depends on the functional and structure state of erythrocyte membrane. The rate of glucose penetration to erythrocytes in various functional states was measured. The influence of external affects (physical and chemical, for example used in medicine surface-active substances) on function of the erythrocyte membrane was studied. Obtained results allow us to offer the elaborated device and methods of measurement as for scientific so for clinical investigations.

Thin films of hydroxylapatite were created on Ti and Ti6A14V flat substrates by excimer laser ablation. Wide scale of deposition conditions were varied as deposition atmosphere (vacuum, pure water vapors, mixture of Ar and water vapors), substrate temperature, target-substrate distance and energy density. Results of physical, mechanical and biological analysis are summarized. No clear correlation between physical and mechanical properties and results of biological tests (activity of T-lymphocytes) were found.

The detection of several substances in a mixture can be realized by using luminescent markers and discriminating them by their luminescence lifetimes. The number of simultaneously detectable analytes can be increased by extending the time region of the lifetimes of the dyes. The fluorescence lifetimes of commercial available organic dyes do not exceed 100 ns. Longer decays are found among the complexes of transition metals. Therefore the photophysical properties of a number of luminescent ruthenium(II) tris(alpha-diimine) complexes in air equilibrated aqueous buffer solution were measured at room temperature. Their application as luminescence markers in diagnostics and analytics is discussed. The possibility of emission enhancement by addition of detergents to reduce water quenching and by addition of sodiumsulfite to reduce oxygen quenching was investigated. Some of the ruthenium compounds were encapsulated in carboxylated polystyrol beads. Resulting changes of the luminescence decays are presented. The possibility of increasing sensitivity by multilabeling with dyed beads in analytical applications is discussed.

The limit of the slope efficiency with respect to absorbed pump power is investigated in erbium-doped 3-micrometer crystal lasers. It depends on the major population mechanisms of the system. Fluoride hosts are favorable due to the long lifetime of the upper laser level. The calculated slope efficiency in Er:YLF approaches 56% when pumping at 970 nm. This value clearly exceeds the Stokes limit of 35% because of energy recycling via interionic upconversion. A laser slope efficiency of 40% in Er(15%):YLF is experimentally obtained under Ti:sapphire pumping.

Temperature variations of an Er:YAG laser crystal during optical pumping with varying flashlamp pulse duration and spectral composition have been determined by utilizing temperature dependence of a cw argon laser line absorption. Time-resolved measurements of crystal gain at 2.94 micrometer have also been performed for the same set of pumping conditions. Additionally, temperature and gain profiles inside the laser rod have been determined owing to good spatial resolution of the implemented temperature measurement method.

One of the most promising applications of the laser is its use as an optical knife for surgery, especially for microsurgery. Efficient cutting with a minimum of undesired damage can be achieved if the laser energy is absorbed within a very thin layer and if a pulse duration is chosen that prevents diffusion of the heat by thermal conduction. Absorption of the laser energy can occur either in specific absorbers such as blood or melanin or unspecifically in water. According to the absorption properties of water, a good laser for cutting should emit radiation with about 3 micrometer wavelength.

Theoretical modeling of high-power thulium-sensitized holmium fluorozirconate glass (Tm:Ho:ZBLAN) fiber lasers operating on the 2 micrometer transition in holmium is presented. High output power in single-mode is achieved by pumping the inner cladding of double clad fiber with single-mode core with high-power multimode cw diode lasers. The higher output powers possible with the double-cladded fiber laser (or DCFL) over the core- pumped fiber laser means that these particular lasers are suited to a number of medical applications which require output of high power and low divergence. In a preliminary step to optimize these devices, a computer model has been developed to analyze the performance of the device when the length of the fiber configuration and doping are varied. It is shown that the form of the coupling coefficient which relates the transfer of power from nonabsorbing modes to absorbing modes which propagate within the inner cladding and core of the fiber is paramount to the operation of the DCFL.

The saturation of the 2.71 micrometer laser in a 5000 ppm erbium doped ZBLAN single-mode fiber pumped at 791 nm was spectroscopically analyzed. The bleaching of the ground state, the absorption coefficient at the pump wavelength and the fluorescence intensities over a wide wavelength range have been measured simultaneously during laser emission. The saturation of the 2.71 micrometer emission is explained by co-lasing at 850 nm.

The erbium 2.7-micrometer fluorozirconate fiber laser is investigated in computer simulations and experiments. An output power of 158 mW at 2.7 micrometer is achieved from an erbium- doped single-mode fiber cascade laser. The output power is limited only by the pump power available from the Ti:sapphire laser. The slope efficiency of 23.3% in the cascade-lasing regime is close to the calculated limit of 27%. It is shown that this cascade regime represents the most efficient system for the operation of an erbium 2.7-micrometer fluorozirconate fiber laser.

Since 1851, the image quality of ophthalmoscopes has improved dramatically. Moreover, during this period the intensity of light used in ophthalmoscopy also has increased, but the exact limits of transient light damage at high light levels are unknown. Therefore, we have developed an instrument which functions as a low light level ophthalmoscope and ocular fundus camera. The basic structure is similar to the von Helmholtz ophthalmoscope. The beamsplitter is built of a thin glasplate. The fundus is illuminated through the outer part of the pupil. The cornea reflection is suppressed by ring-shaped illumination and orthogonal polarizers in the illumination and observation beam path. The microchannel image intensifier tube has a luminous gain of between 30,000 and 70,000 lm/lm. The image of the fundus can be observed at the fluorescent screen of the tube. The images presented by the new type ophthalmoscope allow an oriented examination of the fundus. In particular, the optic nerve and adjacent retinal vessels can be viewed with drastically reduced illumination levels compared to conventional ophthalmoscopes. During examination no mydriasis is required and the patient does not experience dazzle. The main range of applications are patients with light sensitive fundi or dazzle-sensitive eyes.

Laser Doppler flowmetry (LDF) is a method that can be used for measuring blood flow changes in the microcirculation. We have contributed to the development of a new device for LDF, based on digital signal processing. A method for correcting the disregarding of frequency components was developed, by approximating the noise-free Doppler spectrum with an exponential shape. The frequency components from 40 kHz to 50 kHz can be used to correct for white noise. We introduced variable resistors for the case common mode components from both detectors have different magnitudes. However, after adjustment we found that noise may still be present. We have observed, that cutting off at 150 Hz suppresses many noise contributions and still provides sufficient Doppler information. For the transfer of a moment calculated from 150 Hz - 20 kHz into 0 - infinity Hz, the correction method mentioned above can be applied.

The method and design of a system for the laser treatment of ischemic heart disease is presented. Our conceptual approach to the development of the system is based on the theoretical and experimental works of the east and west scientists about positive influence of low intensity laser irradiation in the near infrared range by treatment of cardiovascular diseases. The method and system allow active influence on the subepicardial collateral blood circulation with near infrared (NIR) laser irradiation in wavelength ranges of 0.86-1.06 mkm. The presented technique makes it possible to achieve a higher effectiveness of treatment due to individual choice of radiation parameters on the basis of analysis of the patient conditions before and after laser therapy and due to simultaneous affection at several points of the human body. Finally, results of the tests are presented, which prove given methods.

A dual-channel imaging system for endoscopic observations of photosensitizer's exogeneous fluorescence has been designed, manufactured and clinically tested. The system is computer- controlled and serves for imaging of malignant tumors.

Optical parametric oscillators offer extremely large tuning ranges from the ultra violet to the mid-infrared with high pump to output conversion efficiencies and providing continuous or pulsed operation from nanosecond to femtosecond domains. These sources have many potential applications in medicine in diagnostic techniques, selective laser induced fluorescence and tunable source therapeutics. We present various cavity architectures from narrow bandwidth, low power devices to high power extraction and amplification with a view to assessing the potential of the OPO in medicine.

Advances in short arc technology and improvements in optical filters have led to the construction and biomedical testing of a portable non-laser light source with the optobiological props of a laser. The low-cost device delivers 1.5 W directly or 1 W via a 4 mm flexible light guide within a rectangular 30 nm bandwidth. Its output can be rapidly centered on any wavelength from 300 nm to 1200 nm. Beam uniformity is plus or minus 2% for tested diameters of 50 mm. The relative biological effectiveness (RBE) of this prototype was very similar to a photodynamic therapy (PDT) laser system (87 plus or minus 3%, p less than 0.05 in vitro and with minor modifications no significant difference in vivo p equals 0.62) and dermatological trials show it to be an advance over current clinical treatment for Bowen's disease. The prototype is being further developed with monofilament fiber delivery for interstitial biomedical applications. Its portability and spectral versatility make the device more suitable than a laser for a range of phototherapy treatments. These include the IR for photocoagulation and hyperthermia, the visible region for PDT and fluorescence diagnostics, and UV for dermal photosensitivity tests.

Preclinical studies of a new light emitting diode light source suitable for photodynamic therapy at 650 nm are described. The light source is found to produce effective cell kill using the colo26 cell line and the photosensitizer m-THPC. The performance of the LED source for PDT in tissue is evaluated in comparison with a copper vapor pumped dye laser by measuring depth of necrosis obtained in normal rat liver. Similar depths of necrosis are obtained. It is concluded that the device shows promise as an alternative light source for photodynamic therapy with m-THPC.

Pain is a serious medical problem; it inflicts huge economic loss and personal suffering. Pain signals are conducted via small, non- and partially myelinated A-delta and C nerve fibers and lasers are particularly well suited to stimulating these fibers. Large myelinated fibers convey touch and vibration information and these fibers are also discharged when contact thermodes and other touch pain stimuli are used and this would give a more muddled signal for functional imaging experiments. The advantages of lasers over conventional methods of pain stimulation are good temporal resolution, no variable parameters are involved such as contact area and they give very reproducible results. Accurate inter-stimulus changes can be achieved by computer control of the laser pulse duration, pulse height and repetition rate and this flexibility enables complex stimulation paradigms to be realized. We present a flexible carbon dioxide laser system designed to generate these stimuli for the study of human cerebral pain responses. We discuss the advantages within research of this system over other methods of pain stimulation such as thermal, electrical and magnetic. The stimulator is used in conjunction with functional magnetic resonance imaging, positron emission tomography and electrophysiological methods of imaging the brain's activity. This combination is a powerful tool for the study of pain-induced activity in different areas of the brain. An accurate understanding of the brain's response to pain will help in research into the areas of rheumatoid arthritis and chronic back pain.

The strong angular and base dependence of the Fabry-Perot interferometer reflectivity is used for the increase of beam quality and power of medical lasers. The smaller divergency makes the use of thinner (more bendable) optical fiber possible.

There exists two main directions of the electro-optical analysis of suspended cells. In each of these directions electrophysical properties of the cell are used. Cells in the first direction of research are considered as a whole object. Cells are influenced by electrical field, which permits us to reveal their electrophysical properties. The results of electro-optical cell suspension sample measurements are thus: (1) Determination of heterogeneity of cell population on electrophysical properties and morphometrical characteristics; (2) Determination of absolute total concentration of cells and concentration of cells in each faction with distinguished electrophysical properties. The second direction of research provides determination of electrophysical parameters of cell structures on designed homogeneous fraction. The mutual relation of a structure and physiological function of cells permits us to use the value and kinetic of electrophysical cell structure parameters change for determination of their physiological characteristics. In the manuscript the theoretical bases of each direction of the analysis and the results of their use for monitoring of biotechnological processes are considered.

THe use of a photothermal detection system for the study of interacting biomolecules is described. Two different setups are presented to demonstrate the performance of the system by measurements of DNA/intercalator-samples immobilized on membrane supports used in molecular biological techniques.