Blue-green Spectral Region Research Articles

Лазерная оптико-телевизионная активно-импульсная система подводного видения

The article is devoted to the practical application of the active-pulse observation method to provide underwater vision in conditions of diffusing seawater. The laser optical-television active-pulse underwater vision system (APS UV) developed for the implementation of this method, based on synchronized pulsed laser illumination of objects of observation and video recording by a specially developed optical-television camera based on a highly efficient photodetector module with a sensitive structure «Third+ Generation Image Intensifier Tube with extended blue-green spectral region – Digital CMOS-matrix», provides the formation of video images of underwater objects in seawater with the determination of the range to them. A laser optical-television active-pulse underwater vision system (AIS PV) developed for the implementation of this method, based on synchronized pulsed laser illumination of underwater observation objects and video recording by a specially developed optical-television camera based on a highly efficient photodetector module with a sensitive structure “III+ generation electron-optical converter by – digital CMOS matrix”, which provides the formation of video images of underwater objects in seawater with the determination of the range to them. The article provides information on the physical prerequisites for the technical implementation of underwater vision in scattering seawater, as well as information on technical solutions for creating key elements of APS UV that can increase the range of vision by cutting off back scattering interference when observing in seawater. This advantage distinguishes APS UV from conventional optical television systems, in which back scattering is superimposed on the resulting image of the object, significantly reducing the range of vision and the quality of the resulting image. The results of the work performed are aimed at increasing the contrast of the image of the observed underwater object and, consequently, the range of vision of the APS UV. The article describes the developed model of the APS UV.

Autumn sunlight promotes aboveground carbon loss in a temperate mixed forest

BackgroundPhotodegradation of plant litter plays a pivotal role in the global carbon (C) cycle. In temperate forest ecosystems, the exposure of plant litter to solar radiation can be significantly altered by changes in autumn phenology and snow cover due to climatic change. How this will affect litter decomposition and nutrient dynamic interacting with forest canopy structure (understorey vs. gaps) is uncertain. In the present study, we conducted a field experiment using leaf litter of early-fall deciduous Betula platyphylla (Asian white birch) and late-fall deciduous Quercus mongolica (Mongolian oak) to explore the effect of change in autumn solar radiation on dynamics of litter decomposition in a gap and understorey of a temperate mixed forest.ResultsExposure to the full-spectrum of not only significantly increased the loss of mass, C, and lignin, but also modified N loss through both immobilization and mineralization during the initial decomposition during autumn canopy opening, irrespective of canopy structure and litter species. These effects were mainly driven by the blue-green spectral region of sunlight. Short-term photodegradation by autumn solar radiation had a positive legacy effect on the later decomposition particularly in the forest gap, increasing mass loss by 16% and 19% for Asian white birch and Mongolia oak, respectively.ConclusionsOur results suggest that earlier autumn leaf-fall phenology and/or later snow cover due to land-use or climate change would increase the exposure of plant organic matter to solar radiation, and accelerate ecosystem processes, C and nutrient cycling in temperate forest ecosystems. The study provides a reference for predictive research on carbon cycling under the background of global climate change.

Plasma-deposited reactive species assisted synthesis of colloidal zinc-oxide nanostructures

A surface-wave microwave discharge is applied to deposit reactive oxygen and nitrogen species (RONS) into the liquid subsequently used as a medium for laser ablation of a Zn metallic target. It is shown that during laser ablation in plasma-treated liquids the H2O2 concentration decreases, while in deionized water (DIW) significant H2O2 is produced. Meanwhile, the pH—initially adjusted by applying reductive metals—increases in the acidic liquids and decreases in the alkaline ones. During months of storage the pH of colloids stabilize around pH 6, which insures the long-term stability of RONS. It is demonstrated that in DIW metallic Zn NPs are created, which gradually oxidize during storage, while in the plasma-treated liquids ZnO NPs are produced with the mean size of 18 nm. In the alkaline plasma-treated liquid the NPs form large aggregates, which slows the dissolution of NPs. In the acidic and neutral solutions besides NPs nanosheets are also formed, which during storage evolve into nanosheet networks as a result of the dissolution of NPs. The band gap of the colloidal ZnO is found to decrease with the formation of aggregates and nanosheet networks. The ZnO NPs ablated in plasma-treated liquids exhibit a high-intensity visible emission covering the green-to-red spectral region. The photoluminescence spectra is dominated by the orange-red emission—previously not detected in the case of laser-ablated ZnO NPs and attributed to the interstitial Zn and oxygen sites—and the yellow emission, which can be attributed to the OH groups on the surface. It is shown that during months of storage, due to the dissolution of NPs and formation of nanosheets, the intensity of the visible emission decreases and shifts to the blue-green spectral region.

Photoluminescence and cathodoluminescence of CaCu(Si[formula omitted]O[formula omitted])[formula omitted

Photoluminescence, cathodoluminescence and light absorption spectra of CaCu(Si2O5)2 have been explored in the spectral range from ultraviolet to near infrared. The luminescence and light absorption spectral bands have been analyzed to determine their constituent peaks. In photoluminescence spectra, the main very intense luminescence band reaching maximum around the quantum energy of 1.42 eV has been found to be composed of six spectral components with the strongest one peaked near 1.41 eV. In cathodoluminescence, only three of six lines have been found to constitute this band, with the strongest one peaking also at 1.41 eV. Besides, two much weaker bands of cathodoluminescence—a narrower one peaked at about 2.2 eV and a broad one spreading from the blue–green spectral region to the near UV range—have been detected in the visible and UV spectral ranges at T=300 and 80 K and the e-beam energies of 10, 15 and 30 keV. The shape and peak composition of the latter band depend on the e-beam energy and sample temperature. The origin of the derived spectral peaks is discussed.

Effect of the Synthesis Conditions on the Morphology, Luminescence and Scintillation Properties of a New Light Scintillation Material Li2CaSiO4:Eu2+ for Neutron and Charged Particle Detection

In the present article, the influence of the activator concentration and impurity content of raw materials on the luminescence and scintillation properties of Li2CaSiO4 was studied. Polycrystalline powder material was obtained by the sol–gel method. It was shown that europium had limited solubility in the host lattice with a limiting concentration proximate to 0.014 formula units. The maximum intensity of photoluminescence was observed with a divalent europium concentration of 0.002 formula units; the light yield under alpha-particle excitation was measured to be 21,600 photons/MeV for ~200 μm of coating, and under neutron excitation, it was calculated to be 103,800 photons/n, the scintillation kinetics was characterized by an effective decay time of 157 ns. These properties and the transparency in the visible spectrum make it possible to produce scintillation screens with a coating of Li2CaSiO4 for detecting neutrons, alpha particles and low-energy beta radiation. The low Zeff (~15) of this compound makes it less sensitive to gamma rays. The 480 nm blue emission peak makes this material compatible with most commercial PMT photocathodes, CCD cameras and silicon photomultipliers, which have a maximum quantum efficiency in the blue–green spectral region.

Spectral Dependence of the Energy Transfer from Photosynthetic Complexes to Monolayer Graphene.

Fluorescence excitation spectroscopy at cryogenic temperatures carried out on hybrid assemblies composed of photosynthetic complexes deposited on a monolayer graphene revealed that the efficiency of energy transfer to graphene strongly depended on the excitation wavelength. The efficiency of this energy transfer was greatly enhanced in the blue-green spectral region. We observed clear resonance-like behavior for both a simple light-harvesting antenna containing only two chlorophyll molecules (PCP) and a large photochemically active reaction center associated with the light-harvesting antenna (PSI–LHCI), which pointed towards the general character of this effect.

Ocean color algorithms to estimate the concentration of particulate organic carbon in surface waters of the global ocean in support of a long-term data record from multiple satellite missions

As the concentration of particulate organic carbon (POC) in the surface ocean plays a key role in marine biogeochemical cycles and ecosystems, its assessment from satellite observations of the global ocean is of significant interest. To achieve a global multi-decadal data record of POC by merging observations from multiple satellite ocean color missions, we formulated a new suite of empirical POC algorithms for several satellite sensors. For the algorithm development we assembled a field dataset of concurrent POC and remote-sensing reflectance, Rrs(λ), measurements collected in all major ocean basins encompassing tropical, subtropical, and temperate latitudes as well as the northern and southern polar latitudes. This dataset is characterized by a globally-representative probability distribution of POC with a broad range of values between about 10 and 1000 mg m−3. This development dataset was created with the use of additional inclusion and exclusion criteria based on well-assured and documented consistency of measurement protocols as well as specific bio-optical and particle characteristics of seawater which are consistent with vast areas of open-ocean pelagic environments.To formulate the algorithms the development dataset was subject to parametric regression analysis. Overall we evaluated over seventy formulas for estimating POC from Rrs(λ) using seven distinctly different algorithmic categories, each with a fundamentally different definition of independent variable involving Rrs(λ). Through the goodness-of-fit analysis, we selected the best candidate POC algorithms, referred to as the hybrid algorithms, which are tuned specifically for the spectral bands of SeaWiFS, MODIS, VIIRS, MERIS, and OLCI satellite sensors. These hybrid algorithms consist of two components, the MBR (Maximum Band Ratio)-OC4 cubic polynomial function and BRDI (Band Ratio Difference Index) quintic polynomial function. The MBR-OC4 uses four spectral bands and the BRDI three spectral bands from the blue-green spectral region. The MBR-OC4 algorithm is used for POC > 25 mg m−3 and the BRDI for POC < 15 mg m−3. In the transition region the weighting approach is applied to POC derived from the two algorithmic formulas. While the main role of the BRDI is to improve POC estimates in ultraoligotrophic waters where POC is very low, the MBR-OC4 provides improvements, compared with the predecessor algorithms, over a broader range of POC but especially for relatively high POC values. A preliminary analysis of field-satellite matchup datasets based on SeaWiFS and MODIS-Aqua observations shows improved performance of hybrid algorithms compared with current standard algorithms for both SeaWiFS and MODIS. In addition, a reasonable consistency is demonstrated between POC derived from hybrid algorithms applied to example satellite observations with SeaWiFS, MODIS-Aqua, and VIIRS-SNPP. The suite of newly developed algorithms provides the potential next generation version of global algorithms that better represents the spatial and temporal variability within a broader range of POC than the predecessor global algorithms, while also offering a capability to generate a long-term sensor-to-sensor consistent data record of POC that begins with the launch of SeaWiFS mission in 1997.

Surface‐Dependent Properties and Tunable Photodetection of CsPbBr3 Microcrystals Grown on Functional Substrates

AbstractAll‐inorganic metal halide perovskites are highly attractive materials for optoelectronics and are typically implemented as thin films, nanocrystals, and single crystals with macroscopic and millimeter‐size dimensions. Single crystals with regular shapes in the micrometer range are less explored and present an interesting alternative when a well‐defined and spatially localized response is desired. Here, CsPbBr3 microcrystals are fabricated by simple and fast drop‐casting of a precursor solution on several substrates that for the growth process are heated to temperatures in the range from 80 to 150 °C. The microcrystals have a cubic shape and feature a pyramidal cavity on their top surface that forms due to faster growth at the edges once the growing crystal is attached to the substrate. Distinct heterogeneity in the photoluminescence (PL) and conductivity of the different facets are measured by µ‐PL and conductive atomic force microscopy experiments. Toward device applications, the authors contact single microcrystals on conductive substrates mechanically with a micromanipulator tip. They observe diode‐like current–voltage curves and good photodetector functionality, obtaining a high responsivity of 150–300 A W−1 in the blue–green spectral region under forward bias, and a sharp detection band centered around 540 nm with peak responsivity close to 0.7 A W−1 under reverse bias.

Spectral variations of the remote sensing reflectance during coccolithophore blooms in the Western Black Sea

Among the many calcifying marine organisms, coccolithophores are the major producer of particulate inorganic carbon (PIC). Calcium carbonate plates covering coccolithophores, called coccoliths and released during blooms, are responsible for a large increase of the water reflectance. Aiming at investigating the spectral features of the remote sensing reflectance RRS(λ) of marine waters during coccolithophore blooms, this study exploits the radiometric data of Ocean Color sites of the Aerosol Robotic Network (AERONET-OC) in the Western Black Sea (Galata and Gloria/Section-7) by focusing on bloom events that occurred in 2017 and 2020. The analysis, besides showing elevated RRS(λ) in the blue-green spectral region in the presence of coccoliths, confirms a shift toward the blue of the RRS(λ) spectra as the bloom declines and coccoliths accumulate at the surface. Results also document a decreased capability of determining the bloom state in the presence of optically complex waters such as those associated with river runoff. Finally, the comparison of satellite versus AERONET-OC radiometric data for the extreme conditions created by the presence of coccolithophores, indicates agreements between RRS(λ) not significantly different from those previously determined for various satellite data products in the absence of appreciable concentrations of coccoliths.

Si nanopillar arrays as possible electronic device platforms

This paper explores the possible use of silicon nanopillars as electronic devices. The silicon nanopillars studied in this work were fabricated by electron beam lithography and by plasma ion etching of silicon wafers. The electrical and physical properties of these pillars with full width at half maximum ranging from few nanometers to 100 nm and length of few hundreds of nanometer have been investigated by time-resolwed photoluminescence, infrared spectroscopy and current-voltage characteristics. An ultrafast blue luminescence component competing with non-radiative recombination at surface defects was quantified as originating from the no-phonon recombination. This component involved two decay processes with a peak energy at around 500 nm, which have the fast component close to femtosecond time scale. The emission exhibits also a slow component in the red spectral region with a time constant in the nanosecond regime. The nanopillars have been smoothened in an attempt to passivate surface defects. The results are indicative of an increase in the lifetimes-of carriers and an enhancement in the red component of the emission with much slower sates. The presence of ultrafast decay at blue-green spectral region is suggestive of the possibility of using the silicon nanopillars as ultrafast switching devices. Silicon nanopillar arrays can also be an ideal platform in trapping and sensing chemical or biological species using diamond NV centers.

Endogenous and exogenous fluorescence diagnosis of tumors in the lower part of the gastrointestinal tract

Endogenous fluorescence measurements using UV-VIS excitation wavelengths revealed a variety of natural fluorophores, including the amino acids tyrosine and tryptophan, coenzymes – NADH and flavin, collagen and elastin. Deep minima in the tumor fluorescence signals were observed in the region 540 – 575 nm related to re-absorption of hemoglobin. Such high haemoglobin content was also found as an indication of the tumor’s vascularization and it was clearly pronounced in all dysplastic and tumor sites investigated ex vivo. A photosensitizer from the family of porphyrins was applied as an exogenous fluorescent marker, namely, delta-aminolevulinic acid/protoporphyrin IX (5-ALA/PpIX). The 5-ALA was administered per os six hours before endoscopic observation and spectral measurements at a dose of 20 mg/kg. A high-power light-emitting diode at 405 nm was used as an excitation source (LED-405, 25 mW, CW, Polironik Ltd., Russia). A fiber was introduced through an endoscopic instrumental channel in order to retrieve information about the fluorescence to a USB4000 micro-spectrometer (OceanOptics Inc., Dunedin, USA). The fluorescence detected from in vivo tumor sites has very complex spectral origins. It consists of autofluorescence, fluorescence from exogenous fluorophores and re-absorption from the chromophores accumulated in the investigated tissue. However, the fluorescence of 5-ALA/PpIX was clearly pronounced in the 630 – 710 nm region, having a significant contrast with the surrounding normal mucosa pale fluorescence in the blue-green spectral region. The precancerous mucosa also revealed a red light signal, but with lower intensity levels than the carcinoma lesions observed in situ. False-positive signals were recognized in case of inflammations in the colon and rectum areas, where 5-ALA/PpIX was accumulated as well.

Synthesis, structure, photophysical properties and evaluation of in vitro cytotoxic activity of homoleptic dipyrrin based palladium complexes

The synthesis of bis(dipyrrinato)palladium(II) complexes (PD1-PD4) from functionalized dipyrromethanes was achieved via a simple and versatile route involving the oxidation of meso-substituted dipyrromethane followed by complexation with palladium acetate. All the complexes were characterized in detail using various spectroscopic techniques and their structures explicitly confirmed by X-ray crystallography. The crystal structures of the complexes PD1 and PD4 revealed an overall ‘zig-zag’ arrangement for the molecules due to the bent geometry of the meso-substituents with respect to the dipyrrin plane. The photophysical properties were meticulously studied; the complexes exhibit weak luminescence in the blue-green spectral region (λem = 500–575 nm) with lifetime of 2.5–3.8 ns. A short triplet state lifetime of 28.97–67.61 ns was observed for the complexes, as determined by nanosecond transient absorption spectroscopy. All the complexes were tested for their cytotoxicity through a trypan blue-based in vitro assay on DLA cancer cell lines and the results were compared with normal spleen cells. Interestingly, low IC50 values were obtained for PD3 against the cancerous cells, whereas the complexes are inactive towards normal cell lines. The antiproliferative activity revealed the potential of these complexes for further development as in vivo anticancer agents.

On the equivalence of near-surface methods to determine the water-leaving radiance.

The equivalence of two radiometric methods relying on a single nadir-view optical sensor to determine the water-leaving radiance LW, namely the Single Depth Approach (SDA) and the Sky-Blocked Approach (SBA), was investigated applying identical hyperspectral radiometers operated on the same deployment platform. Values of LW from SDA and SBA measurements performed in the Black Sea across a variety of waters during ideal illumination conditions and with low-to-slight sea state, exhibited mean absolute differences within 0.5% in the blue-green spectral region and 2% in the red. This result, benefitting of a comprehensive parameterization of optical processes in combination with the characterization of sensors non-linearity, in-water response and reproducibility of absolute radiometric calibrations, indicated ample equivalence of the two near-surface methods in terms of performance and data reduction needs.

A simple method for the preparation of multi-color carbon quantum dots by using reversible regulatory color transformation.

It is known that polychromatic carbon quantum dots (CQDs) can be obtained by doping and surface modification. The layer-wise synthesis of blue and green emitting CQDs (with typical sizes between 3 and 6nm) is described here by adding oxalic acid and by introducing polycarboxy groups. By changing the external environment, the emission of CQDs can be adjusted in the blue-green spectral region (469-527nm) under photoexcitation at 405nm. The findings presented here provide new directions for the reversible regulatory transformation of polychromatic CQDs. The luminescence also is affected by a variety of conditions such as surface defects, degree of polymerization, polarity of external solutions, and hydrogen bonding which is studied in some detail. Graphical abstract Schematic presentation of the blue-green fluorescent transformation of the green carbon quantum dots(G-CQDs) to blue carbon quantum dots(B-CQDs).

Synchronous fluorescence spectroscopy for early diagnosis of citrus canker in citrus species

The current study presents the application of fluorescence emission spectroscopy and synchronous fluorescence spectroscopy (SFS) coupled with chemometrics in diagnosing citrus canker disease in citrus species. Leaf samples were collected from random plants of grapefruit and Mexican lime species from an orchard. Fluorescence spectroscopy demonstrated the disease severity by predicting an increase in the blue–green spectral region and a decline in chlorophyll bands in the citrus leaves. As a result of the disease severity, characteristic changes in the SFS spectrum were observed. Noticeably, SFS provided additional information on the occurrence of significant bands of leaf fluorophores representing various biochemical changes in leaves at different disease stages. The current study led to the inference that a higher intensity of α-tocopherol and gallic acid is found in healthy and asymptomatic leaves; in contrast the band intensity of flavonoids, caffeic acid, tannins, flavins and chlorogenic acid increases in diseased samples, proportionally to the disease severity. Principal component analysis showed a clear separation between healthy and diseased samples. It is important to note that the asymptomatic samples were clustered with the symptomatic samples or remained as a separate group, thus revealing disease initiation, an observation which is impossible to make through visual examination. The results indicate that the spectral signatures obtained through front-face fluorescence spectroscopy as well as through SFS of citrus leaves could be used as fingerprints from the detection viewpoint.

Spectral assessment of deployment platform perturbations in above-water radiometry.

Deployment platforms such as ships, towers or buoys may affect the accuracy of nearby radiometric measurements. Aiming at expanding the know-how on platform perturbations in above-water radiometric measurements, this study investigated the spectral impact of the Acqua Alta Oceanographic Tower (AAOT) on the remote-sensing reflectance RRS as a function of the distance d between the tower and the sensor footprint at the sea surface. This was accomplished by exploiting measurements performed with radiometers operated on deployment rigs extending beyond the AAOT superstructure with sensor viewing angle θ = 40° and relative azimuth ϕ = 90° between sensor and sun. AAOT perturbations were also investigated by increasing the reflectance of the tower through white sheets covering part of its superstructure. Results indicate a spectral dependence of perturbations in RRS more pronounced in the near infrared, significantly increasing with the tower reflectance and decreasing with the inverse square of the distance d. In particular, for distances approaching the platform height, AAOT perturbations are found to be generally well below 1% for measurements performed in the visible spectral region and exceed 2% beyond 800 nm. However, with identical measurement geometry, but increasing the AAOT reflectance through the white cover, perturbations approach 1% in the blue-green spectral region and exceed 2% beyond approximately 600 nm. These findings, yet derived from a distinct tower and for specific measurement conditions, raise awareness on spectral perturbations of deployment platforms in above-water radiometry and additionally provide practical elements for the implementation of measurement protocol allowing to constrain these perturbations below required thresholds.

Computer-Aided Design of Luminescent Linear N-Heterocyclic Carbene Copper(I) Pyridine Complexes.

Multireference configuration interaction methods including spin-orbit interactions have been employed to investigate the photophysical properties of various linear N-heterocyclic carbene (NHC) copper(I) pyridine complexes with the aim of designing performant thermally activated delayed fluorescence (TADF) emitters for use in organic-light-emitting diodes. Our theoretical results indicate that this structural motif is very favorable for generating excited triplet states with high quantum yield. The first excited singlet (SMLCT) and corresponding triplet state (TMLCT) are characterized by dσ → πPy metal-to-ligand charge-transfer (MLCT) excitations. Efficient intersystem crossing (ISC) and reverse ISC (rISC) between these states is mediated by a near-degenerate second triplet state (TMLCT/LC) with large dπ → πPy contributions. Spin-vibronic coupling is strong and is expected to play a major role in the (r)ISC processes. The calculations reveal, however, that the luminescence is effectively quenched by locally excited triplet states if the NHC ligand carries two diisopropylphenyl (DIPP) substituents. When DIPP is replaced with 1-adamantyl residues, this quenching process is suppressed and TADF in the UV spectral regime is predicted to proceed at a rate of about 1/μs. The introduction of +I substituents on the carbene and -M substituents on the pyridine allows tuning of the emission wavelength from the UV to the blue-green or green spectral region.

Promising Organic Active Media for Blue-Green Tunable Lasers

Results of investigation of spectral-luminescent and lasing characteristics of substituted 1,3-oxazoles and 1,3,4-oxadiazoles lasing in the blue-green spectral region are presented. For some compounds, efficiencies of 40 and 38% have been achieved with pump power density of 7 MW/cm2. A 34 nm wide tuning range in the blue-green spectral region with lasing line width of 0.012 nm is shown. A series of laser-active compounds with good solubility in methyl methacrylate capable of effectively lasing is determined.

A CMOS SPAD Line Sensor With Per-Pixel Histogramming TDC for Time-Resolved Multispectral Imaging

A 512 $\times $ 16 single photon avalanche diode (SPAD)-based line sensor is designed in a 0.13- $\mu \text{m}$ CMOS image sensor technology for time-resolved multispectral beam scanned imaging. The sensor has 23.78- $\mu \text{m}$ pixel pitch and incorporates one SPAD array with 49.31% fill factor optimized for detection in the blue–green spectral region, and a second array at 15.75% fill factor optimized for the red-near-infrared response spectral region. Each pixel contains a 32-bin histogramming time-to-digital converter (TDC) with a mean time resolution of 51.20 ps. Histogram bin resolutions are adjustable from 51.20 ps to 6.55 ns per bin. The line sensor can operate in single photon counting (SPC) mode (102.1 giga-events/s), time-correlated SPC (TCSPC) mode (192.4 million-events/s) or on-chip histogramming mode (16.5 giga-events/s), increasing the count rate up to 85 times compared to TCSPC mode. Sensor capability is demonstrated through spectral fluorescence lifetime imaging, resolving three fluorophore populations with distinct fluorophore lifetimes.

New approaches to improve efficacy and reduce side effects of phototherapy for neonatal hyperbilirubinemia using led and laser sources

The article discusses the new opportunities for improving technology of phototherapy for neonatal jaundice using LED and laser sources in order to reduce the level of bilirubin in the blood of infants. It has been shown that several types of LEDs with emission spectrum corresponding to the long-wavelength slope of bilirubin absorption band can be used for therapeutic purposes. At the same time, the efficacy of phototherapy depend on not only from the position of the maximum in emission spectrum of the LEDs within bilirubin absorption band, but also on the spectral width of acting radiation. Based on the study of regularities of infl of optical radiation on the survival of animal cells in culture sensitized with bilirubin it has been concluded that the damaging eff cts are signifi ly reduced upon transition from quasi-monochromatic LED sources to lasers, emitting in the same spectral range. It allows to consider the modern semiconductor lasers emitting in blue and blue-green spectral regions as promising sources for development of phototherapeutic equipment for treating neonatal hyperbilirubinemia.