bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in absorbance of monolayer of living cells induced by laser radiation at 633, 670, and 820 nm
Authors: Karu Tiina I. , Afanasyeva Natalya I. , Kolyakov Sergei.V. , Pyatibrat Ludmila V. , Weiser Leslie
Published: February 2023

Redox absorbance changes in living cells (monolayer of HeLa) under laser irradiation at 633, 670, and 820 nm have been studied by the method of multichannel registration in spectral range 530–890 nm. It has been found that the irradiation causes changes in the absorption spectrum of the cells in two regions, near 754–795 nm (maxima at 757, 775, and 795 nm) and near 812-873 nm (maxima at 819, 837, 858, and 873 nm). Changes occur in band parameters (peak positions, width, and integral intensity). Virtually no changes occur in the red spectral region and a few changes are recorded in the green region near 556–565 nm. The results obtained evidence that cytochrome c oxidase becomes more oxidized (which means that the oxidative metabolism is increased) due to irradiation at all wavelengths used. The results of present experiment support the suggestion (Karu, Lasers Life Sci., 2:53, 1988) that the mechanism of low-power laser therapy on cellular level is based on the electronic excitation of chromophores in cytochrome c oxidase which modulates redox status of the molecule and enhances its functional activity.
Optical topographic reconstruction using photon measurement density function
Authors: Kashio Yoshihiko , Okada Eiji
Published: February 2023

The multi-channel NIR system can obtain the topographic image of brain function in the cortex. Since the light is strongly scattered in biological tissue, the spatial sensitivity of the source-detector pairs is broadly distributed in the brain cortex. This phenomenon causes poor spatial resolution of topographic imaging. In this study, the spatial sensitivity distribution of the source-detector pairs is incorporated into the reconstruction algorithm of the topographic image to improve the spatial resolution.
Small Volume Approximation in First Order Perturbative Approach to the Diffusion Equation
Authors: Esposito R. , Lepore M. , Indovina P.L.
Published: February 2023

First order perturbation approach to the diffusion provides a more realistic model to describe inhomogeneous structures. To this regard, we obtained a general expression of the time-resolved transmittance relatively to a homogeneous turbid medium with an embedded inclusion. This expression was further approximated in the case of a small volume object. Then, we studied the limit and accuracy of this approach concerning on a cubic absorber placed in the centre of the source-detector line of a turbid slab.
High resolution parallel optical coherence tomography in scattering samples
Authors: Laubscher M. , Ducros M. , Karamata B. , Bourquin S. , Lasser T.
Published: February 2023

Parallel optical coherence tomography in scattering samples is demonstrated using a 58 by 58 smart-pixel detector array. A femtosecond mode-locked Ti:Sapphire laser in combination with a free space Michelson interferometer was employed to achieve 4μm longitudinal resolution and 9μm transverse resolution on a 260×260 μm2 field of view. We imaged a resolution target covered by an intralipid solution with different scattering coefficients as well as onion cells.
Laser tweezing near resonance absorption
Authors: Agayan Rodney R. , Schmidt Christoph F. , Gittes Fred , Kopelman Raoul
Published: February 2023

Expressions for radiation—induced forces are presented for the case of a Rayleigh particle at the focus of a Gaussian laser beam. Classical electromagnetic theory was used to obtain the dependence of the scattering and gradient forces on the incident laser frequency, beam convergence angle, and spatial position of the particle in the focus. Numerical analysis performed for particles with a single resonant absorption peak demonstrates the occurrence of enhanced trapping forces at near-resonant frequencies. An indication of the breakdown of the paraxial Gaussian approximation for large convergence angles is also shown by calculation of the scattering force. Use of this technique of gradient force enhancement may provide optical tweezers with enhanced trapping strengths and a degree of specificity.
Non-invasive characterization of anterior segment structures using real-time optical coherence tomography at 1310nm
Authors: Radhakrishnan Sunita , Reeves Diana , Lass Jonathan H. , Bardenstein David S. , Rollins Andrew M. , Westphal Volker , Roth Jonathan E. , Izatt Joseph A.
Published: February 2023

Real-time optical coherence tomography (OCT) was used to visualize and quantify structures in the anterior segment of the eye. Current results of ongoing clinical trials are presented. Preliminary data indicates strong potential for the use of real time OCT as a tool for noninvasive characterization of the anterior chamber angle and for anterior segment biometry.
Photonic Force Microscopy: Simulation of principles and applications
Authors: Rohrbach Alexander , Florin Ernst-Ludwig , Stelzer Ernst H.K.
Published: February 2023

The Photonic Force Microscope is a novel scanning probe microscope based on optical tweezers to hold a probe, which fluctuates in its position due to thermal noise. The three-dimensional position of the probe is detected with high temporal resolution and spatial precision by analyzing the interference of unscattered and forward scattered light. We present the theoretical framework of the optical forces acting on the probe, as well as of the detection signal due to coherent scattering and describe thermal noise position fluctuations by a Brownian dynamics simulation. As an application we simulate the temporal and spatial behavior of a probe tethered to the coverslip (according to the molecular kinesin/microtubule system) at different laser powers and different anchor positions.
Tri-modal spectroscopy as a tool for detecting cervical squamous intraeptihelial lesions in vivo
Authors: Georgakoudi Irene , Sheets Ellen E. , Crum Christopher P. , Mueller Markus G. , Backman Vadim , Feld Michael S.
Published: February 2023

Using intrinsic fluorescence, diffuse reflectance and light scattering spectroscopy we extracted quantitative biochemical and morphological information in vivo about the bulk tissue and the epithelial cell nuclei of ectocervical sites from 44 patients. Significant changes were observed in tissue morphology and biochemistry between normal, squamous metaplastic and squamous intraepithelial lesion (SIL) sites. The combined use of all three spectroscopic techniques (tri-modal spectroscopy) yielded superior results for detecting SILs than any one of the techniques alone.
Determination of the optical parameters of dentin from spatially resolved reflectance and transmittance measurements
Authors: Forster Florian K , Kienle Alwin , Hibst Raimund
Published: February 2023

Measurements of the absolute spatially resolved reflectance and transmittance from dentin slabs were performed using a HeNe laser at λ = 633 mm as source and a CCD camera as detector. Solid phantom slabs were used to test the experimental setup and to enable absolute measurements. The reduced scattering and absorption coefficients were derived by applying a solution of the diffusion theory for a slab geometry as theoretical model. Monte Carlo simulations were used to investigate the validity of the diffusion solution. Compared to other biological tissues large values were found for the reduced scattering coefficient of dry dentin slabs, in which the tubuli were parallel to the slab extension. In addition, we measured a strong dependence of the optical properties on the water content of the dentin slabs. We also found that the anisotropic structure of dentin strongly influences the light propagation and, thus, the derived optical properties.
Study of Serum Fluorescence and Raman Spectra for Diagnosis of Cancer
Authors: Li Xiaozhou , Bai Jing , Lin Junxiu , Liu Huasheng , Ding Jianhua
Published: February 2023

Optical spectroscopy for tumor demarcation was investigated in this study. Laser-induced fluorescence and Raman spectra were measured from normal and tumorous human blood serum in an attempt to discover some values useful in discrimination between normal and tumorous cases. Three Raman peaks were consistently observed from normal blood serum emission using 488.0nm and 514.5nm excitation of an Ar-ion laser, whereas no peak or only slight Raman peaks were detected from tumorous cases. In addition, red shift of fluorescence peak and decrease of fluorescence intensity were observed after samples radiated by laser. According to one thousand twenty-two samples’ spectra, three parameters α, β and Δλ are introduced to distinguish normal, benign and malignant from one another. The application of such parameters in clinical diagnosis was researched. Four hundred and fifty-nine samples were investigated before knowing the result of clinical diagnosis in order to estimate the availability of our criteria.
Detection of Early Bronchial Carcinoma by Imaging of the Tissue Autofluorescence
Authors: Goujon Didier , Glanzmann Thomas , Gabrecht Tanja , Zellweger Matthieu , Radu Alexandre , van den Bergh Hubert , Monnier Philippe , Wagnières Georges
Published: February 2023

Early detection and localisation of bronchial cancer remains a challenging task. One approach is to exploit the changes in the autofluorescence characteristics of the bronchial tissue as a diagnostic tool with improved sensitivity. Evidence exists that this native fluorescence or autofluorescence of bronchial tissues changes when they turn dysplastic and to carcinoma in situ. There is agreement in the literature that the lesions display a decrease in autofluorescence in the green region of the spectrum under illumination with violet light and a relative increase in the red region of the spectrum is often reported. Imaging devices rely on this principle to detect early cancerous lesions in the bronchi. Based on a previous spectroscopic study, an industrial imaging prototype has been developed to detect early cancerous lesions in collaboration with the firm ‘Richard Wolf Endoskope GmbH’. A preliminary clinical trial, involving 20 patients, with this spectrally optimised system proved that autofluorescence can detect lesions that would otherwise have remained invisible even to an experienced endoscopist under white light illumination. A systematic analysis of the autofluorescence images indicated that real-time decisional functions can be defined in order to reduce the number of false positive results. Using this method, a Positive Predictive Value (PPV) of 75% was achieved using autofluorescence only. A PPV of even 100% was obtained when white light mode and auto fluorescence mode were combined under the applied conditions. Furthermore, the sensitivity was estimated to be twice as high in AF mode than in WL mode.
Fluorescence imaging in the upper gastrointestinal tract for detection of dysplastic changes
Authors: Sukowski U. , Ebert B. , Ortner M. , Mülle K. , Voderholzer W. , Weber-Eibelb J. , Dietel M. , Lochs H. , Rinneberg H.
Published: February 2023

During endoscopy of the esophagus fluorescence images were recorded at a delay of 20 ns after pulsed laser excitation simultaneously with conventional reflected white light images. To label malignant cells (dysplasia, tumor) 5-aminolaevulinic acid was applied prior to fluorescence guided biopsy. In this way premalignant and malignant lesions were detected not seen previously during routine endoscopy.
Optical detection of (pre-)malignant lesions of the oral mucosa: autofluorescence characteristics of healthy mucosa
Authors: de Veld D. C. G. , Witjes M. J. H. , Roodenburg J. L. N. , Star W. M. , Sterenborg H. J. C. M.
Published: February 2023

Previous clinical results demonstrate the potential of in vivo autofluorescence spectroscopy for early detection of (pre-)malignant lesions of the oral mucosa. For reliable diagnosis, it is necessary to study autofluorescence spectra of healthy mucosa first. We measured excitation-emission maps in healthy subjects and subjects with a history of cancer in the head -neck region. Our results show that different anatomical locations produce distinct autofluorescence spectra. Influences of, among others, smoking and drinking habits require further investigation.
Clinical NIR spectroscopy and optical tomography of the testis
Authors: Hampel U. , Schleicher E. , Zepnick H. , Freyer R.
Published: February 2023

Optical tomography and NIR spectroscopy are potential methods to improve the diagnosis of testicular pathologies. To evaluate the methods clinically we developed a special measurement device with the capability of spatially resolved laser spectroscopy and optical tomography of the testis. Simple spectroscopy is primarily used to obtain global tissue optical properties of the testis and to find correlations of optical parameters with type and stage of certain pathologies. Optical tomography is applied to visualize spectral contrasts in limited tissue volumes, such as tumors. In the course of the study we will determine whether NIR techniques posses the required specifity and sensitivity to give additional quantitative information about tissue perfusion parameters and to serve for a tumor differentiation.
Non invasive optical monitoring of rat brain and effects of the injection of tracers for blood flow measurements
Authors: Sablong R. , Grillon E. , Hugon O. , Derouard J.
Published: February 2023

Near infrared spectroscopy using either broad band reflectance spectrophotometry or monochromatic illumination has been carried out to monitor non invasively the changes of the concentrations of chromophores in rat brain induced by the intravenous injection of various contrast agents (indocyamne green, ultrasmall magnetic particles suspension, albumine, dextran, or saline solution alone). Depending of the wavelength and of the absorption spectrum of the injected compound the bolus can be seen either by a decrease or an increase of the transmitted light, this latter due to induced dilution of the blood by the bolus. We suggest that this could be used to determine the arterial input function the contrast agent needed to perform absolute cerebral blood flow imaging by nuclear magnetic resonance.
Monte-Carlo simulation of light propagation in multi-layered tissue with cleared inclusions
Authors: Savchenko Eugeny P. , Tuchin Valery V.
Published: February 2023

In this paper, we described our results of Monte-Carlo simulation of light propagation in a multi-layered biological tissue, such as the human brain and the skin with optical clearing. The main goal of our simulation was a study of a time delay of the detected signal and the signal form. This report includes optical clearing simulation with some variants of clearing tissue structure. As well as we described general principles of our algorithms construction.
Microspectral investigation of hair of one girl during 6 years by laser emission analysis
Authors: Surmenko Elena L. , Sokolova Tatiana N. , Tuchin Valery V.
Published: February 2023

Multiple chemical elements of clinical and nutritional interest were measured in the hair of a girl – cerebral palsy patient. Sixteen samples of hair were cut and investigated to determine time and nutrition trends by using laser and arc emission spectroscopy.
HIV Detection by optical spectroscopy
Authors: Joshi N.V. , Doria M. , Medina H.
Published: February 2023

Reliable and economical Human Immnodeficiency Virus (HIV) testing was achieved by optical absorption spectroscopy of the core of the hair in the range of 400 nm to 800 nm. In HIV + patients, extra optical active material is deposited in the core and optical absorption spectra, recorded in polarized radiation reveal special features, which can be used for guidance, detection, monitoring and control.
Preliminary results from multi-center clinical trials for detection of cervical squamous intraepithelial lesions using a novel full-field evoked tissue fluorescence based imaging instrument
Authors: Dattamajumdar A.K. , Wells D. , Parnell J. , Ganguly D. , Wright T.C.
Published: February 2023

We report preliminary results from a multi-center trial of evaluating the performance of a novel, full-field multispectral tissue fluorescence imaging system (Cerviscan™) designed to detect cervical squamous intraepithelial lesions. Spectral data from multiple regions of 48 patients enrolled from clinical performance sites in the US and Canada are included in this preliminary analysis. This includes 30 women used for the training set and 18 use for the testing set. In the testing set, 37/43 SIL and 70/80 NonSIL regions were correctly identified for a sensitivity of 86% and specificity of 87.5%. Cerviscan™ locates cervical precancerous lesions with high sensitivity and specificity and has the potential to permit ‘see and treat’ patient management.
In vivo absorption spectroscopy in brain using small optical fiber probes: effect of blood confinement
Authors: Bradu A. , Sablong R. , Julien C. , Troprès I. , Payen J.F. , Derouard J.
Published: February 2023

Broad band light absorption spectroscopy in the visible range (520-590nm) has been carried out using implanted small optical fibers to probe the hemodynamics of deep tissues (striatum) in rat brain subjected to hypoxia. We observe a decrease of the cerebral blood oxygenation by a factor of up to two, while the cerebral blood volume (CBV) does not seem to increase significantly. However, nuclear magnetic resonance measurements of CBV in the same conditions using a magnetic contrast agent show that CBV increases by about 50%. This shows that absorption spectroscopy in the visible range strongly underestimates the CBV, probably due to the confinement of blood in vessels. This effect is confirmed by absorption spectroscopy measurements performed in phantoms with similar geometry.
Optical Diffusion Imaging Data from Speckle Pattern Frequency Correlations
Authors: Webster M. A. , Webb K. J. , Weiner A. M.
Published: February 2023

We demonstrate a convenient technique for determining the temporal response and scattering parameters of a diffusive medium using laser speckle pattern frequency correlations. Experimental results using an external-cavity tunable laser diode are presented. This approach can be extended to provide data for image reconstruction based on a diffusion model.
In vivo and in vitro study of immersion clearing dynamics of the skin
Authors: Genina Elina A. , Bashkatov Alexey N. , Sinichkin Yuri P. , Lakodina Nina A. , Korovina Irina V. , Simonenko Georgy V. , Tuchin Valery V.
Published: February 2023

Experimental results on in vivo and in vitro immersion clearing dynamics of the skin under action of the osmotic agent are presented. The significant decrease of the human skin reflectance in vivo under action of glucose solution is demonstrated. In vitro experiments with dyed immersion agents have shown that the immersion mostly penetrates into skin tissue through the dermal layer. Diffusion of the immersion agent through the stratum corneum barrier was insignificant. It was shown that hypodermic injection of the immersion agent is an effective way for the agent administration. The time-dependent contrast of the blood perfused areas in the cleared skin was estimated. The diffusion coefficient of 40%-glucose solution in skin in vivo was estimated as D = (2.56 ± 0.13)·10-6 cm2/sec.
Application of phosphorescence quenching by O2 to the investigation of O2 delivery to ocular tissues
Authors: Chamot Stéphane R. , Petrig Benno L. , Pournaras Constantin J. , Percicot Christine L. , Lambrou George N. , Riva Charles E.
Published: February 2023

The technique of phosphorescence quenching by O2 (PQ) allows the non-invasive measurement of the partial pressure of oxygen in blood (

pO

2

blood

). This technique and its application to the investigation of the

pO

2

blood

in the microvasculature of the retina and optic nerve head (ONH) of two animal species is described. Using the imaging mode of PQ, 2-dimensional

pO

2

blood

maps were obtained to investigate the response of the

pO

2

blood

to various physiological stimuli in miniature pigs and the effect of experimental glaucoma in monkeys. Applied in its focal mode, PQ allows measurements of the

pO

2

blood

with a time resolution of 1 second and is adequate to investigate the

pO

2

blood

time course during light stimulation.
Laser induced temperature distribution in cell layers
Authors: Edelmann Martin , Meier Thomas , Rupp Markus , Vilpoux Kathia
Published: February 2023

Thermal stimulation of single cells and cell layers is used for investigations of temperature associated processes like necrosis or apoptosis. Simulations of temperature distributions in layered structures on various substrates are presented. In order to verify the simulations a diode pumped IR-cw laser system was developed. The TEM00 output beam at a wavelength of 2.8 µm was focused on biological material to compare visible effects with the calculations.
A novel diagnostic method, for the detection of far-red fluorescence emission from several tumor-seeking photosensitisers
Authors: Theodossiou T. , Hovhannysian V. , Kastaniotis P. , Politopoulos K. , Yova D.
Published: February 2023

A novel detection method for malignant tumour detection through specific accumulation of far-red emitting photosensitisers, has been developed. The set-up, based on He-Ne (633 nm) excitation was tested with phantom malignancies models using photosensitisers on chicken tissue. Intensity vs. depth of tissue measurements as well as photobleaching measurements were performed. Point by point fluorescence imaging indicated that the formation size is not significantly distorted with respect to depth of location.
A novel diode laser system for photodynamic therapy
Authors: Samsøe Eva , Petersen Paul M. , Andersen Peter E. , Andersson-Engels Stefan , Svanberg Katarina
Published: February 2023

In this paper a novel diode laser system for photodynamic therapy is demonstrated. The system is based on linear spatial filtering and optical phase conjugate feedback from a photorefractive BaTiO3 crystal. The spatial coherence properties of the diode laser are significantly improved. The system provides an almost diffraction limited output which is efficiently coupled into a 50 µm core diameter fiber. The optical power transmitted through the fiber is increased by a factor of six when the feedback is applied to the diode laser. 85 percent of the power from the freely running laser diode is extracted in a high-quality beam and 80 percent of the output power is extracted through the fiber. The power transmitted through the fiber scales linearly with the power of the laser diode, which means that a laser diode emitting 1.7 W multi-mode radiation would provide 1 W of optical power through a 50 µm core diameter fiber. The system is compact, portable, stable, and easy to operate.
Laser-induced interstitial thermotherapy in treatment of recurrent nodular goiter and thyroid cancer
Authors: Seliverstov O.V. , Privalov V.A. , Lappa A.V. , Demidov A.K. , Faizrakhmanov A.B. , Yarovoy N.N.
Published: February 2023

Laser-induced interstitial thermotherapy was performed in 29 patients with recurrent nodular and multinodular goiter, and in 3 patients with recurrent inoperable thyroid cancer. There were used transcutaneous puncture under ultrasonic control, diode lasers with wavelength 805, 980, and 1060 nm, quartz monofibers, special computerized thermometer with microthermocouples. Disappearance or significant reduction of nodes in the most goiter cases, and regress of tumor in the cancer cases were marked during observation period (0.5 - 2.5 years).
Myocardial Expression of the Vascular Endothelial Growth Factor (VEGF) after Endocardial Laser Revascularization (ELR)
Authors: Rommerscheid J. , Theisen D. , Schmücker G. , Brinkmann R. , Broll R.
Published: February 2023

Background. Endocardial laser revascularization (ELR) is a new technique to treat patients with severe coronary artery disease (CAD) in a percutaneous approach. The results show a significant improvement of symptoms, but the mechanism of action is still unknown. One main theory is the angiogenesis for which Vascular Endothelial Growth Factor (VEGF) is the keypromotor. We investigated immunohistochemically the VEGF-expression after ELR in porcine hearts over a timeperiod of four weeks. Methods. ELR was performed with a single-pulse Thulium:YAG laser. 15 pigs were treated with ELR and the hearts were harvested at five timeperiods: directly (group I), 3 days (group II), 1 week (group III), 2 weeks (group IV) and 4 weeks (group V) after ELR. Each group consisted of three pigs. Immunohistochemically the VEGF-expression was assessed by staining with a polyclonal antibody against VEGF and cellcounting using an expression index (VEGF-EI) Results. A maximum of VEGF-expression was found three days (group II) after ELR with a VEGF-EI of 97%. At 1 week (group III) the VEGF-EI was similar high with 93%. Along the timecourse the index decreased to 22% at 4 weeks (groupV). Conclusions. Our findings show that ELR leads to an local upregulation of VEGF around the channels. The resulting angiogenesis could be the mechanism for the relief of angina.
Depth of dentin modification induced by Nd:YAG laser irradiation
Authors: Maciel Alessandro S. , Redígolo Marcela L. , Munin Egberto , de Mello Guilherme P. S. , Pacheco Marcos T. T.
Published: February 2023

Ten human third molars were used in this in vitro study to analyze the depth of dentin modification induced by a Nd:YAG laser. This technique has been used as a procedure to treat dentin hypersensitivity to air and to mechanics stimulation. Five techniques of sample preparation were used in this work but just one of them preserves the area under study for observation. The samples were irradiated with 170 mJ of energy per pulse and an average depth of 100 µm of modification of the dentin was observed under scanning electron microscopy (SEM).
Optoacoustic detection of selective RPE cell damage during µs-laser irradiation
Authors: Schüle Georg , Joachimmeyer Elke , Framme Carsten , Roider Johann , Birngruber Reginald , Brinkmann Ralf
Published: February 2023

Objective: The selective damage of the retinal pigment epithelium (RPE) with repetitive µs laser pulses is a new technique for the treatment of several retinal diseases. RPE can selectively be damaged by simultaneously sparing off the adjacent photoreceptor tissue. Objective of this study is to investigate whether optoacoustic (OA) transients occurring during irradiation might be used to control the invisible treatment effect.

Setup: A train of frequency doubled Nd:YLF laser pulses (527 nm, 1.7µs pulse length, 500Hz rep. rate) were applied via a laser slit lamp on porcine RPE samples. The acoustic transients were recorded with a broadband transducer.

Results: At low radiant exposures (< 100 mJ/cm2) we found a bipolar pressure transient due to thermoelastic expansion of the RPE. The pressure waves from the individual pulses of one pulse train show nearly identical transients. The transients differ slightly from different sites on the sample. At higher radiant exposures (> 150 mJ/cm2), the OA transients differ from pulse to pulse within a pulse train, which can be attributed to microbubble formation around the strong absorbing melanosomes inside the RPE cells. FFT spectra of the OA transients show slight differences in the frequency spectrum with the different radiant exposures.
Optoacoustic Imaging for Ophthalmology
Authors: Oberheide Uwe , Jansen Birte , Bruder Ingo , Lubatschowski Holger , Welling Herbert , Ertmer Wolfgang
Published: February 2023

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.
Analyzing biomolecular interactions by variable angle ellipsometry
Authors: Wu J.Y. , Lee C.K. , Lee J.H. , Shiue S.C. , Lee S.S. , Lin Shiming
Published: February 2023

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 ellips ometer biosensor is able to undertake an accurate measurement on biomedical interaction.
DNA Biochips based on Surface-enhanced fluorescence (SEF) for high-throughput interaction studies
Authors: Stich Norbert , Mayer Christian , Bauer Georg , Schalkhammer Thomas
Published: February 2023

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.
Optoacoustic images of early cancer in forward and backward modes
Authors: Karabutov A.A. , Andreev V.G. , Bell B. , Fleming R.D. , Gatalica Z. , Motamedi M. , Savateeva E.V. , Singh H. , Solomatin S.V. , Thomsen S.L. , Henrichs P.M. , Oraevsky A.A.
Published: February 2023

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.
Parallel optical reading of micromechanical sensors arrays for biology and environmental studies
Authors: Roger Jean Paul , Boccara A. Claude , Potier Marie-Claude , Guirardel Matthieu , Bergaud Christian
Published: February 2023

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 Δf. 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.
Measurements of optical tweezers stiffness
Authors: Malagnino N. , Pesce G. , Sasso A. , Arimondo E.
Published: February 2023

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 μm at different laser powers.
The optical properties of lymph flow in single microvessels: biomicroscopic, speckle-interferometric and spectroscopic measurements
Authors: Galanzha Ekateryna I. , Tuchin Valery V. , Ulyanov Sergey S. , Solovèva Anastasiya V. , Luo Qingming , Cheng Haiying
Published: February 2023

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.
Pulsed laser-Doppler flowmetry for monitoring deep perfusion
Authors: Kolkman Roy G.M. , Hondebrink Erwin , Bolt René A. , Steenbergen Wiendelt , de Mul Frits F.M.
Published: February 2023

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).
Modified crossed-cylinder aberroscope
Authors: Ozolinsh Maris , Racene Diana , Cikmacs Peteris
Published: February 2023

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.
Combined optical tweezers and optical stretcher in microscopy
Authors: Singer W. , Frick M. , Haller T. , Dietl P. , Bernet S. , Ritsch-Marte M.
Published: February 2023

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.
Eye model with controllable lens scattering
Authors: Paeglis Roberts , Ozolinsh Maris , Cikmacs Peteris , Andersson-Engels Stefan
Published: February 2023

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.
THz imaging of histo-pathological samples
Authors: Knobloch P. , Schmalstieg K. , Koch M. , Rehberg E. , Vauti F. , Donhuijsen K.
Published: February 2023

We investigate the potential of THz imaging for the examination of histo-pathological samples. Data obtained on a pig larynx and on a human Ever 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.
Application of computer stereo vision systems to biological researches
Authors: Buyburin V.B. , Nikonov A.V. , Volkov Y.P. , Dolgov V.M. , Dolgov Y.M. , Naymova E.V.
Published: February 2023

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.
Transmission electron microscopy study of thin sections of ultrasmall quantity of cells
Authors: Volkov Uryi P. , Konnov Nikolai P. , Novikova Olga V.
Published: February 2023

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.
Development of a novel non-invasive sensor for the determination of the blood glucose concentration
Authors: Böckle Stefan , Rovati Luigi , Ansar Rafat R.
Published: February 2023

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.
A Progressive Wavelet Volume Rendering System
Authors: Yang Xue Dong , Liu Yang
Published: February 2023

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
Thermosonic imaging of cracks: Applications to teeth
Authors: Han Xiaoyan , Favro L.D. , Thomas R.L.
Published: February 2023

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.
Spectral optoacoustic imaging using a scanning transducer
Authors: Paltauf G. , Köstli K.P. , Frauchiger D. , Frenz M.
Published: February 2023

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.
Photoacoustic imaging in phantom materials and in vivo
Authors: Pilatou Magdalena C. , Voogd N. , de Mul F. F.M. , Marani E. , van Adrichem L.N.A.
Published: February 2023

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 stuctures by using infrared light1,2. 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.
Evaluation of Mo-Based Multilayer EUV Mirrors
Authors: Takenaka Hisataka , Kawamura Tomoaki , Ishii Yoshikazu , Haga Tsuneyuki , Kinoshita Hiroo
Published: February 2023

The soft x-ray reflectivities and the effects of thermal annealing on both reflectivity and on the layered structures of Mo-based multilayers, such as Mo/Si, Mo/SiC, Mo/C, Mo/B, Mo/BN, Mo/B4C, MoSi2/Si and Mo5Si3/Si were evaluated. The Cu-Kα x-ray and soft x-ray reflectivities of the Mo/Si and Mo/B multilayers markedly decrease after annealing above 400°C. On the other hand, the reflectivities of the other Mo-based multilayers decrease only slightly for annealing temperatures up to 700°C. TEM observation reveals markedly less thermally induced deterioration in Mo/SiC, Mo/C, Mo/BN, M0/B4C, MoSi2/Si and Mo5Si3/Si multilayers than in Mo/Si multilayers. These results suggests that Mo/SiC, Mo/C, Mo/BN, Mo/B4C, MoSi2/Si and Mo5Si3/Si multilayers are superior to Mo/Si multilayers in terms of thermal stability.
Multilayer Coatings for the EUV Lithography Front-End Test Bed
Authors: Vernon S. P. , Carey M. J. , Gaines D. P. , Weber F. J.
Published: February 2023

Good illumination uniformity at the mask and wafer planes, and high
wafer throughput in the EUVL front-end test bed facility at LLNL
require graded period multilayer (ML) coatings on several of the
optics. The ML deposition was accomplished using a newly developed
deposition technique which avoids the use of "uniformity masks" to
define the spatial dependence of the ML period variation. The
capabilities of the process in providing the specified ML coatings are
discussed for both EUVL condenser and imaging systems.
Multilayer Facilities for EUV Lithography
Authors: Windt D. L. , Waskiewicz W. K.
Published: February 2023

We describe the multilayer deposition system we have developed for coating large-area, figured optics, as required for a practical extreme-ultraviolet (EUV) lithography tool. In this system, multilayers are deposited by magnetron sputtering, and coating uniformity on figured optics is adjusted by implementing contoured, shaped baffles during deposition. We also describe the EUV reflectometer we have developed, which is capable of measuring the reflectance versus wavelength across the surface of these optics, so that the coating uniformity can be determined with the required precision. Finally, we present some recent results wherein these facilities and techniques have been used to deposit high-reflectance coatings onto a variety of spherical and aspherical substrates.
Beryllium Based Multilayers for Normal Incidence EUV Reflectance
Authors: Skulina Ken , Alford Craig , Bionta Richard , Makowiecki Dan , Gullikson E. M. , Soufli Regina , Kortright J. B. , Underwood J. H.
Published: February 2023

We report the experimental results of beryllium based multilayer mirrors for use in the 11.4 nm region. Mirrors using molybdenum as the high-Z material have demonstrated 68.7% peak reflectance at 11.3 nm.
Achievement of Low Stress in Mo/Si Multilayer Mirrors
Authors: Nguyen Tai D. , Khan-Malek Chantal , Underwood James H.
Published: February 2023

The feasibility of low stress Mo/Si multilayers was studied in an attempt to fabricate flat semi-transparent multilayer mirrors as beam splitters near 13 nm wavelength. Stress in periodic multilayer structures is independent of the number of bilayer pairs, and depends strongly on the multilayer period, and the ratio of the layer thicknesses. Transition of stress from compressive to tensile state is observed in Mo/Si multilayers as Γ, the ratio of the Mo layer thickness to the multilayer period, increases. Low stress Mo/Si multilayers have been achieved, and achievement of Mo/Si beam splitters is demonstrated.
Effect of Contamination and Oxide Layers on Scattering and Reflectivity of Multilayer Mirrors
Authors: Underwood J. H. , Gullikson E. M. , Ng Waiman , Ray-Chaudhuri Avijit , Cerrina Franco
Published: February 2023

Previously we reported that when molybdenum is deposited as the top layer of a molybdenum-silicon multilayer mirror, the reflectivity for normal incidence reflection at 130 Å or longer wavelengths decreases with time if the mirror is exposed to air. This effect results from progressive oxidation of the top Mo layer. We have additionally found that the decreased reflectivity is accompanied by strong scattering from the oxide layer, which expands and buckles during the oxidation process. The strong scattering reduces the image contrast and signal/background in imaging experiments using Mo/Si coated optics. However, both the reflectivity degradation and the increased scattering can be reversed by a boiling water etch of the the top surface.