Doctor of Phys.-Math. Sciences. — Professor, Valery Alexandrovich Loiko,
Principal researcher of the Scattering-Media Optics Laboratory
of the B.I. Stepanov Institute of Physics
of the National Academy of Sciences of Belarus (IP NANB).

Photovoltaics: Solar cells

Enhancement of the performance of photovoltaic cells through increasing light absorption due creation of particulate structure of active layer is investigated.

We simulated spectral and integrated over the terrestrial solar spectral irradiance “Global tilt” ASTM G173-03 absorption coefficient.

In the wavelength range of small absorption index of c-Si (0.8-1.12μm) the integral absorption coefficient of the particulate monolayer can be more than 20 times higher than the one of the plane-parallel plate of the equivalent volume of material. In the overall considered range (0.28-1.12μm) the enhancement factor up to ~1.45 for individual monolayer is observed.

Maximum value of the spectral absorption coefficient approaches unity for multilayers consisting of large amount of sparse monolayers of small particles.

Fig. 1. Spectral absorption coefficients of monolayers with different diameters D
and the proper plane-parallel equivalent plates of c-Si with proper thicknesses h. Filling factor η=0.5 (a), η=0.9 (b).

One of the possible realizations of the solar cell based on gradient multilayer of active layer is presented schematically below.

Fig. 2. Schematic presentation of the solar cell based on gradient layered structure of active layer (side view). The circles with the dashed lines are particles of the semiconductor material. 1- transparent electrodes, 2- transparent dielectric layers, 3- rear electrode. The circles sectioned by the dashed lines are the particles with the p-n junctions indicated by these lines. The transparent electrodes connect the parts of particles with the same conduction type (p or n). The transparent dielectric layers separate the transparent electrodes and zones of different conduction types of particles. The rear electrode 3 provides the electrical conductivity and reflection of light back into the active layer.

The integral absorption coefficient of the consentration- and size-gradient multilayer for the multilayer composed of seven monolayers can be more than 40% greater than the one of the "non-gradient" system.

The considered particulate structures of active layer are promising for creation of the high efficiency thin-film solar cells.

---

Miskevich A. A., Loiko V. A. Light absorption by a layered structure of silicon particles as applied to the solar cells: theoretical study // Journal of Quantitative Spectroscopy & Radiative Transfer. – 2014. – Vol. 146, – P.355–364.

Miskevich A. A., Loiko V. A. Solar cells based on particulate structure of active layer: Investigation of light absorption by an ordered system of spherical submicron silicon particles // Journal of Quantitative Spectroscopy & Radiative Transfer. –2015, –V.167, –P. 23–39. http://dx.doi.org/10.1016/j.jqsrt.2015.08.003

Miskevich AA, Loiko VA, Inventors. B.I. Stepanov Institute of Physics of NAS of Belarus, assignee. Photocell. Russian Federation patent RU 2491681; 2012 March 11.

Coherent transmittance and reflectance spectra of layered periodic disperse structures

The model to describe coherent transmission and reflection coefficients of monolayers is proposed. The features in transmittance interference minima of the monolayers with short- and long-range order are described.

On the spectrum of monolayer with short-range ordering (partially-ordered), the minimum corresponds to the maximum of the extinction efficiency factor. For a monolayer with the long-range ordering (regularly-packed), a similar minimum takes place. The spectrum for the regularly-packed monolayer has an additional sharp coherent transmittance minimum (and the coherent reflection maximum), which is due to the periodicity in particles locations. These extremes occur at wavelengths comparable to the particle sizes and the distances between them.

The developed technique allows one to analyze the coherent transmittance and reflectance of the imperfect 2D planar photonic crystals.

Fig. 1. Schematic view of highly concentrated monolayer with triangular lattice of monodisperse spherical particles. Normal illumination, T_c and R_c are the coherent transmission and reflection coefficients.

Fig.2 illustrates spectrum of monolayer with short-range ordering (partially-ordered), and with the long-range ordering.

The spectral dependence of the coherent transmission coefficients T_c of the high-ordered monolayers of Al₂O₃ particles with a hexagonal lattice (solid line) and partially ordered monolayer (dashed line) with the same filling factor (η = 0.5). Particle diameter D = 0.3μm. The numbers 1, 2 and 1′ indicate the minima of the transmission, characteristic for regularly packed and partially ordered monolayer of particles, respectively.

Fig.3. Schematic representation of the monolayer with the hexagonal lattice of spherical particles (top view).

The photonic band gap for multilayers consisting of close-to-regularly-packed monolayers (planar photonic crystals with imperfect lattice) and partially-ordered monolayers of particles are investigated using the transfer matrix method.

Fig. 4. Schematic representation of a system of plane-parallel monolayers of particles (side view along planes of monolayers).

Here, m_i and h_i are the complex refractive index and the thickness of i-th layer L_i, respectively; If_i is i-th are the numbers of interfaces (particle monolayer); t_ij and r_ij are the amplitude coefficients of coherent transmission and reflection of monolayers (interfaces) for the wave that propagates in the direction of incidence of light (indicated by the thick arrow (“Inc. light”)); t_j,i and r_j,i are the amplitude coefficients of coherent transmission and reflection of monolayers (interfaces) for the wave that propagates in the direction that is opposite to the incident wave (i < j); T_c and R_c are the energy coefficients of coherent transmission and reflection of the multilayer.

The transmission spectra of multilayer structures (multilayers) have three types of sharp minima due to interference of waves. Their position and size are determined by the concentration, size, optical constants of the particles, the regularity of their arrangement in the plane of the monolayer, the period of the layered structure and the thickness of multilayers. The illustration is given in Fig.5.

Fig. 5. Spectra of the T_c (a) and R_c (b) of a monolayer (two-dimensional planar photonic crystal (PPC)) with the hexagonal lattice of Al₂O₃ particles and multilayer consisting of 12, 30, and 60 such PPCs in air. Spacing between the adjacent monolayers is h=0.3μm. η=0.5, D=0.3μm. The digits 1, 2, and 3 indicate the types of transmission minima are inherent in the PPC (minima 1 and 2) and in the layered disperse system (minimum 3) (see the description in text). Gray vertical lines split figures into two parts: in part I only monolayer spectrum is shown, in part II the monolayer and the multilayer spectra are displayed.

Some data for coherent transmittance and reflectance spectra of a system consisting of a glass plate coated with monolayers of spherical alumina particles are shown below. Creation of antireflection coatings does not need high ordering in particle locations. Otherwise, the arrangement of particles in monolayer plays a crucial role for selective reflectors and transmission filters. The reflection coefficient of a glass plate can be significantly reduced by using two-sided coating with monolayers of alumina particles.

Fig. 6. Schematic representation of the multilayer system with monolayers of monodisperse spherical Al₂O₃ particles on the top and bottom surfaces of the glass plate.

Fig. 7. Spectra of the T_c (a) and R_c (b) of the uncoated plane-parallel glass plate (thick line) and the system of monolayers with hexagonal lattice of Al₂O₃ particles (thin solid lines) on the top and bottom surfaces of the glass plate. Thickness of the glass plate is 2mm. Filling factor η=0.5. Numbers near the lines before and after comma indicate particle diameters (in micrometers) of the top and bottom monolayers, respectively.

Comparison the results obtained by the developed model and the known experimental data for the photonic band gap.

Fig. 8. Dependences of the spectral position of the minimum in transmission of the photonic band gap (λ_PBG) for a regular structure of spherical SiO₂ particles placed in different media on refractive index of the medium n_env. The results of calculations are indicated in circles, experimental results of Bogomolov (Phys. Rev. E 55,7619) are indicated in squares. For convenience, the symbols are connected by straight lines. n_env=1.0 (air), 1.328 (methanol), 1.361 (ethanol), 1.426 (cyclohexane), and 1.497 (toluene).

The results can be used to optimize antireflection coating, diffuses, neutral and spectral filters of the transmitted and reflected light. The proper layer characteristics are determined. The results can be used to estimate the degree of ideality of the photonic crystal arrangement by the data on spectral dependences of the coherent transmission and reflection coefficients, retrieve characteristics of the ordered particulate structures, etc.

---

Loiko V. A., Miskevich A. A. Coherent Transmission and Reflection Spectra of Ordered Structures from Spherical Alumina Particles // Optics and Spectroscopy. – 2013, – V. 115, No. 2, - p. 274–283.

Miskevich A. A., Loiko V. A. Layered periodic disperse structures of spherical alumina particles // Journal of Quantitative Spectroscopy & Radiative Transfer. –2014. –V.136. – P.58-70. http://dx.doi.org/10.1016/j.jqsrt.2013.05.013.

Retrieval characteristics of three-dimensional ordered particulate structures by the photonic band gap data

A method to retrieve parameters of spherical particles arranged into ordered structures by the coherent transmittance spectra is proposed. It is based on the solution of the inverse problem using data on the photonic band gap. The solution has been obtained within the quasicrystalline approximation of the multiple wave scattering theory and the transfer matrix method.

Fig.1. Schematic view of a highly concentrated multilayer of spherical particles.

Fig. 2.(a) Actual (filled squares) and retrieved (circles and triangles) refractive indices for multilayer consisting of 200 monolayers with a triangular lattice of SiO₂. Gray circles for retrieval by a position of the band gap λ_PBG, open triangles for retrieval by transmittance minima of the band gap T_PBG). The numbers near the points denote the wavelengths of the PBG minimum λ_PBG in the spectra of the multilayer in air, λ_PBG=0.4614μm (1), methanol, λ_PBG= 0.5469μm (2), ethanol, λ_PBG= 0.5543μm (3), cyclohexane, λ_PBG= 0.5737μm (4), and toluene, λ_PBG= 0.5953μm (5). (b) The relative retrieval error: the gray circles and open triangles are for retrieval by λ_PBG and T_PBG, respectively.

---

Miskevich A. A., Loiko V. A. Method for Retrieving the Refractive Index of Ordered Particles from Data on the Photonic Band Gap // Journal of Experimental and Theoretical Physics, – 2014, – Vol. 119, No. 2, – P. 211–226.

Miskevich A. A., Loiko V. A. Three-dimensional ordered particulate structures: method to retrieve characteristics from photonic band gap data. // Journal of Quantitative Spectroscopy and Radiative Transfer. – 2015, –V.151, –P. 260-268.

Miskevich A.A., Loiko V.A., Inventors. B.I. Stepanov Institute of Physics of NAS of Belarus, assignee. Method to determine refractive index of particles forming мultilayered ordered structure (optional). Russian Federation patent RU 2550159 C2; 2013 Aug. 20.

Filters for visible and infrared radiation

The features of anomalous light scattering in a layer containing ordered optically soft particles are described.

Simulations disclose that in the layer with two-layered subwavelength-sized particles the bleaching and darkening effects can be implemented. In the first case transmittance increases while in the second case transmittance decreases with volume concentration.

Fig.1. Schematic representation of side view of the layer.

The results show the way to optimize characteristics of the transmission filters for visible and infrared spectral regions.

Fig. 2. Dependence of transmittance T on the wavelength for layer with two-layered particles at volume concentration 0.01(curve 1), 0.4 (curve 2), and 0.6 (curve 3). The core radius R_c = 0.2mkm. Refractive index of core n_c = 1.2. The shell radius R_s = 0.3mkm. Refractive index of shell n_s = 0.9. Refractive index of matrix n_m = 1.0. The layer thickness is 20mkm.

The developed model can be used for light scattering description in liquated glasses, filled liquid crystals, polymer-filled nematics, optical filters, paints, etc.

---

Berdnik V.V. and Loiko V. A.. Light scattering by ensemble of nonabsorbing correlated two-layered particles: specific feature for spectral dependence of extinction coefficient // Applied Optics. –2011, –V.50, –№.21.–P. 4246-4251.

Loiko V. A., Berdnik V. V. Light Scattering in a Layer of correlated optically soft particles // Optics and Spectroscopy. – 2006, – Vol. 101, No. 2, P. 303–308.

Berdnik V. V., Loiko V. A. Angular structure of radiation scattered by a disperse layer with a high concentration of optically soft particles // Quantum electronics. – 2006. - Vol. 36, № 11. – P. 1016– 1022.

Quenching effect (zero coherent transmittance)

This is the result of the interference between incident and forward-scattered waves.

At the Single-Scattering Approximation (SSA) coherent transmittance is zero if the following conditions are fulfilled:
L=0.5 and η=2/Q.

Here η - is the filling coefficient of the monolayer, Q is the extinction factor of particle, parameter L is determined by an amplitude scattering function. The effect takes place for monodisperse and polydisperse systems and systems when multiple scattering in the monolayer is essential as well. In that cases the conditions are changed.

The characteristics particles and their concentration to obtain zero coherent transmittance are shown in Fig. The calculations are fulfilled for homogeneous monodisperse spherical nonabsorbing particles at the SSA. The proper values of size parameters x=πd/λ (d is the particle diameter, λ is the wavelength) and filling factors η of the monolayer are indicated as x₀ and η_o.

Values of refractive index (n), size parameters (x0), and filling coefficient (η_o) at which coherent transmittance T=0.

The results can be used to optimize characteristics of scattering and absorption by a monolayer and a slab of monolayers; to create scattering and rejection spectral transmission filters, tunable filters, etc.

---

Ivanov A.P., Loiko V.A., Dick V.P. Features in coherent transmittance of a monolayer of particles //JOSA A. – 2000. – No. 11. – P. 2040-2045.

Loiko V.A., Konkolovich A.V. Interference effect of coherent transmittance quenching: theoretical study of optical modulation by surface ferroelectric liquid crystal droplets // J. Phys. D: Appl. Phys. – 2000. - Vol. 33. – P. 2201-2210.

Konkolovich A.V., Loiko V.A., Presnyakov V.V., Zyryanov V.Ya. The interference blanking of the light passing through the monolayer film of polymer-encapsulated nematic liquid crystals // JETP Lett. – 2000. – V. 71, № 12. – S. 710-713.

Electrically-tunable liquid crystal filters based on the Christiansen effect

Electrically controllable (tunable) spectral filters make it possible to control spectral composition of electromagnetic radiation and considerably simplify the design of electrooptical instruments. Using these filters it is possible create simple and highly functional optical devices and instruments with new service properties.

One way to solve this problem is to use dispersion of small particles in liquid crystal. The dispersion is placed between two parallel substrates, which are transparent for radiation to be filtered and coated with transparent electrodes. The filter is based on the Christiansen effect.

We proposed a technique to calculate characteristics of the filters.

Fig.1. Schematic representation of a tunable dispersiontion filter. 1 - liquid crystal, 2 - transparent electrically conductive layer 3 – particles, 4 – incident light, 5, 6 – scattered and directly transmitted light, respectively.

Fig. 2. The transmission spectra of Al₂O₃-MBBA. The filter thickness 50 (1) 100 (2), 200 (3) 400 (4), and 800μm (5). Particle diameter 20 μm, volume concentration of particles is 0.5, the field of view is 0,1rad.

---

Dick V. P. and Loiko V. A. Transmission Spectra of Tunable Dispersion Filters of the Type of Small Particles–Liquid Crystal // Optics and Spectroscopy. – 2014, – Vol. 117, No. 1, – P. 111–117.

Asymmetry of the angular structure of light in polar scattering angle

We have shown that, for the Polymer Dispersed Liquid Crystal (PDLС) films containing liquid crystal droplets with inhomogeneous boundary conditions, the angular structure of the scattered light can be asymmetric with respect to the polar scattering angle.

Fig. 1. Schematic presentation of director configuration on the surface of liquid crystal droplet with inhomogeneous boundary conditions.

Fig. 2. Textures of LC droplets in crossed polarizers with homogeneous (W=0 and W=100%) and inhomogeneous boundary conditions (IBC) at different values of parameter W. The value of W is determined by the ratio of the height of segment surface of the droplet with normal boundary conditions to droplet diameter as it is shown in Fig. 1. No applied field. Left picture shows a droplet with bipolar director configuration, right picture shows a droplet with radial director configuration

The figures below illustrate the asymmetry of the angular distribution of transmitted radiation over the polar scattering angle.

Fig. 3. The dependence of the intensity (I_vv component) of light scattered by a monolayer of spherical liquid crystal droplets with inhomogeneous boundary conditions on the polar scattering angle. The fraction of the droplet surface with the normal boundary conditions W = 75 (curve 1), 50 (curve 2) and 25% (curve 3). The values of the azimuthal angle and the angle of polarization of the incident light are equal to zero.

The angular structure of the scattered light is asymmetric with respect to the polar angle. This asymmetry is most pronounced at W= 50%, i.e., at equal fractions of the tangential and normal boundary conditions at the droplet surface.

Fig. 4. Dependence of I_vv-component of the light intensity scattered by a monolayer of spherical LC droplets (diameter 5μm) with inhomogeneous boundary conditions at different values of filling factor η=0.01, 0.02, 0.03 (a), η=0.1, 0.2, 0.4 (b).

This effect can be used, for example, to create new types of displays for automatic cash terminals.

---

Loiko V.A., Zyryanov V.Ya., Maschke U., Konkolovich A.V., Miskevich A.A. Small-angle light scattering and transmittance of polymer film, containing liquid crystal droplets with inhomogeneous boundary conditions // Journal of Quantitative Spectroscopy & Radiative Transfer. – 2012. –V.113. – P.2585-2592.

Optical Model of Transient Light Scattering in Ferroelectric Liquid Crystals

An optical model for the effect of field-induced transient scattering in ferroelectric liquid crystals is proposed. Scattering processes are described by introducing an optically anisotropic matrix where transient domains (scatterers) are generated. The results are obtained for a plane parallel layer of ferroelectric liquid crystals with a planar helicoidal structure under normal illumination with a linearly polarized plane wave.

Fig. 1. Schematic representation of the structure of SmС^⚹LC reorientation in the control field. (x, y, z) is the laboratory coordinate system; P_s is the spontaneous polarization vector; θ is the angle of the LC molecules relative to the normal to the z axis; φ is the azimuth angle bold arrows indicate the projection of directors on the plane of the sample (y, z); p₀ is the pitch of the helix; a) projection of a helical structure in the plane of the sample in the absence of the control field (E = 0); b) a single-domain structure in the positive control field (E = +E_mn); c) a single-domain structure in the negative control field (E = — E_mn).

Fig. 2. The dependence of the coherent transmission T_c on the normalized control field E^⚹_n with a symmetric deviation of the polarization plane of the incident light relative to the axis of the helix for different tilt angles θ at refractive indexes of liquid crystal: n_⊥=1.5, n_ll=1.7. The wavelength of the incident light λ=0.6328μm. The thickness of the layer is 5.2μm.

The results can be useful at 3D volumetric and 2D liquid crystal displays development.

---

Loiko V. A., Konkolovich A. V., Miskevich A. A. Optical Model of Transient Light Scattering in Ferroelectric Liquid Crystals // Journal of Experimental and Theoretical Physics, -2009, - Vol. 108, No. 3, – p. 535–545. http://link.springer.com/article/10.1134/S1063776109030169

Loiko V.A., Konkolovich A.V., Miskevich A.A. Transient light scattering in helix ferroelectric liquid crystal cells // Liquid Crystals. – 2009. – Vol. 36, No.4. – P. 365-370.

Polymer-dispersed liquid-crystal film with nanosized nematic droplets

The models to describe extinction and polarization state of light transmitted through a polymer-dispersed liquid-crystal (PDLC) film with nanosized, spherical, nonabsorbing nematic droplets are created.

Scattering properties of a single droplet are described by the Rayleigh–Gans approximation. Propagation of coherent light field is described in the frame of the Foldy–Twersky theory. The concept of multilevel order parameters is used. Equations for extinction coefficients, phase shift, and polarization of transmitted light for layers with random and oriented droplets are written and discussed. Conditions for circular and linear polarization of light are determined. Polarization-independent focusing of light is investigated.

Fig. 1. Schematic representation of a flat lens with axially symmetric LC droplet distribution in the PDLC film.

Fig. 2. Schematic representation of a combined lens comprising a PDLC film with uniform LC droplet distribution and a glass lens.

Figure 3 shows the focal length plotted versus the normalized applied field E_n for the combined lens.

Fig.3. Focal length ƒ vs. E_n for converging-diverging (hermaphrodite) lens.

Comparison with experiment

Fig. 4. Focal length ƒ_e vs. applied voltage U_rms. Curve and symbols represent theoretical and experimental results [S. Sato, Opt. Rev. 6, 471], respectively.

The results obtained can be used to design devices for light modulation based on composite liquid crystal materials: optical filters, polarizers, phase plates, polarization plane rotators, and lenses with variable focal lengths.

---

Loiko V. A. Polymer Films with Nanosized Liquid-Crystal Droplets: Extinction, Polarization, Phase, and Light Focusing. Сhapter 9 in “Nanodroplets” ed. by Z. M. Wang. Springer. New York, Heidelberg, Dordrecht, London. 2013. P. 195-235.

Loiko V. A., Konkolovich A. V. Focusing of Light by Polymer-Dispersed Liquid-Crystal Films with Nanosized Droplets // Journal of Experimental and Theoretical Physics. – 2006, – V. 103, No. 6, – P. 935–943.

Lisinetskaya P. G., Konkolovich A. A., Loiko V.A. Polarization properties of polymer dispersed liquid crystal film with small nematic droplets // Applied optics. – 2009. –Vol.48, No.17. – P. 3144-3153.

Liquid crystal material for modulation of optical and infrared radiation

Polymermethacrylate (PMMA) and polyvinyl butyral (PVB) thin films with the dispersed liquid crystal droplets are obtained by the solvent-induced phase separation method.

The use of PVB as a polymer matrix enables one to obtain absolutely transparent (with no scattering of visible light) film. The value of the phase shift linearly depends on the voltage of applied electric field. It can reach 4 radians at the applied electric field voltage of about 20V/μm

The material can be applied for - displays, electro-optical modulation of the intensity and phase of the wave, creation of electrically switchable optical elements of the visible and infrared radiation, optical communication lines, flat lenses and other optical elements.

Photos below illustrate the change in the transmission cell designed for phase modulation.
Two limiting cases: field-off (1) and field-on (2) are displayed.

---

Dmitriev S.M., Dick V.P., Kostyuk N. N., Dick T.А., Loiko V.А. Experimental studies of light-wave phase shift by polymer dispersed liquid crystal films // Semiconductor physics, quantum electronics and optoelectronics. –2010. –V.13, No.2. – P. 132-136.

Retrieval of characteristics of dispersed particles by the Neural Networks method

The retrieval of characteristics of particles and their concentration is one of the most important problems in ecology, medicine, electronics, photonics, etc.

The characteristics of particles can be retrieved by information on the angular structure of scattered light. This is a “fingerprint” of the particle. The “one by one” regime of measurement is often used. In such a case the large amount of particles is measured in a squeezed time. To retrieve particle characteristics the neural networks method is used. The advantage of this method is a high speed. It admits determination of particle characteristics in a real-time scale.

Neural networks in application to scanning flow cytometry

In the scanning flow cytometry the operation is based on analysis of light, scattered by cells flying with a high rate (up to 5000 cells per second). A set of variants of the neural networks is created by us. One of them is high order correlation neural networks. For example the errors of retrieval of radius R, real, imaginary and imaginary k parts of refractive index by a four-point single-level correlation neural network at k<0.03 do not exceed 0.1 μm, 0.02, and 0.003, respectively (for particles with 0.6mkm <R < 10.6 μm, 0<k<0.03, and refractive index 1.02<n<1.38.

Neural networks in application to aerosol particles characterization

The possibility to retrieve parameters of spherical homogeneous nonabsorbing particles by information on intensity of light scattered in one, two and three angles from the angular range from 10° to 170° is investigated and the proper networks are created. We considered aerosol particles with refractive index ranging from 1.3 to 1.7. It is shown that the use of polychromatic radiation helps to smooth out dependence of the intensity of the scattered light on the refractive index and increase significantly the retrieval accuracy.

Fig. 1. Schematic representation of the neural network calculator with three inner layers of neurons (a) and the single neuron (b).

Sizing of particles in a binary mixture

The results which illustrate sizing of spheroidal and cylindrical particles in a binary mixture are shown below

Fig. 2. Schematic drawing of a particle illumination. a is the major semi-axis; b is theminor semi-axis. The symmetry axis of the particle is oriented in a direction determined by axial and azimuthal angles θ₀ and φ₀, respectively. I₀ is the incident light intensity.

Fig. 3. Retrieved parameters: radius of the equivolume sphere R_e=(ab²) ^1/3 for spheroids and R_e=(3ab²/2)^1/3 for cylinders; and shape parameter e_e = (a+b)/(a-b), and orientation direction θ_oe of a particle in a mixture of prolate spheroidal and cylindrical particles. The measurement error δ=1%. Quadrupole discrimination function.

---

Berdnik V. V., Loiko V. A. Neural networks for particle parameters retrieval by multiangle light scattering. Chapter 7 in “Light Scattering Review10: Light Scattering and Radiative Transfer”, ed. by A. A. Kokhanovsky. Praxis Publishing Chichester, UK .Springer, Springer-Verlag Berlin, Heidelberg. 2016. p. 291– 340.

Berdnik V., Mukhamedyarov R., Loiko V. Characterization of optically soft spheroidal particles by multi-angle light scattering data using the neural networks method // Opt. Lett. – 2004. - Vol. 29. - P. 1019-1021.

Berdnik V., Loiko V., Gilev K., Shvalov A., Maltsev V. Characterization of spherical particles using high-order neural networks and scanning flow cytometry // Journal of Quantitative Spectroscopy & Radiative Transfer. – 2006. –Vol. 102. – P. 62-72.

Loiko V.A., Berdnik V. V. Retrieval of size and refractive index of spherical particles by multi-angle light scattering the neural networks method application // Applied optics. – 2009. –Vol.48, No.32. – P. 6178-6187.

Study of the peripheral blood human leukocytes

Quantitative data on cell structure, shape, and size distribution are obtained by optical measurement of normal peripheral blood granulocytes and lymphocytes in a cell suspension are obtained. The cell nuclei are measured in situ. The distribution laws of the cell and nuclei sizes are estimated. The data gained are synthesized to construct morphometric models of a segmented neutrophilic granulocyte and a lymphocyte.

Models of interrelation between the cell and nucleus metric characteristics for granulocyte and lymphocyte are created. The discovered interrelation decreases the amount of cell-nucleus size combinations that have to be considered under simulation of cell scattering patterns. It allows faster analysis of light scattering to discriminate cells in a real-time scale.

Our morphometric data meet the requirements of scanning flow cytometry dealing with the high rate analysis of cells in suspension. The findings can be used as input parameters for the solution of the direct and inverse light-scattering problems in scanning flow cytometry, dispensing with a costly and time-consuming immunophenotyping of the cells, as well as in turbidimetry and nephelometry.

Fig. 1. Images of T-lymphocytes with narrow (upper part) and wide (lower part) cytoplasmic ring. Differential interference contrast mode.

Fig. 2. Histogram of the ratio between major axes of lympocytes and nuclei. Individual No. 12

Fig. 3. Scatter plot and linear regression (solid line) of nucleus and lympocyte sizes for T-lymphocytes. Individual No.10. Number of measured cells N=1089.

Fig. 4. Micrograph of the mononuclear cells for a patient with AML. The living cells in suspension are sandwiched between an object-plate and cover-slip, as in a “microcuvette”. Micrograph is made with differential-interference contrast (DIC) microscope (DMLB2, Leica) by the microscope-mounted digital camera (Leica DC 150).

Fig. 5. Histograms of the maximal linear sizes for mononuclears of the AML patient (black) and a sepsis patient (white).

The cell models developed can contribute to theoretical grounding of cell discrimination and diagnosis methods. These models make it possible to establish relationships between the cell structure and the angular pattern of scattered light to determine dominant and secondary origins of light scattering by a cell. This can provide background for better biological and medical interpretations of the scattering patterns, to improve discriminating and diagnostic capabilities of immunophenotyping-free scanning flow cytometry.

The findings show that it is possible to screen individuals of risk groups by the immunophenotyping-free scanning flow cytometry for inexpensive and rapid provisional detecting of persons suspected as infected with some viruses.

Mononuclear size distributions (MSDs) are proposed to use as a criterion of additional information for diagnostics and monitoring of acute leukemia.

---

Loiko V.A., Ruban G.I., Gritsai O.A., Gruzdev A.D., Kosmacheva S.V., Goncharova N.V., Miskevich A.A. Morphometric model of lymphocyte as applied to scanning flow cytometry // Journal of Quantitative Spectroscopy & Radiative Transfer. – 2006. - Vol. 102. - P. 73-84.

Ruban G.I., Kosmacheva S.M., Goncharova N.V., Van Bockstaele D., Loiko V.A. Investigation of morphometric parameters for granulocytes and lymphocytes as applied to a solution of direct and inverse light scattering problems // Journal of Biomedical Optics. – 2007. – Vol. 12 (4). – P. 044017-1-044017-11.

Ruban G.I., Berdnik V.V., Goncharova N.V., Marinitch D.V., Loiko V.A. Light scattering and morphology of the lymphocyte as applied to flow cytometry for distinguishing healthy and infected individuals // Journal of Biomedical Optics. 2010. –V.15, No.5. – P. 11-19.

Ruban G. I., Goncharova N. V., Marinitch D. V., and Loiko V. A. Size distribution of mononuclears as marker of acute leukemia // International Journal of Advance in Medical Science. –2015, – Vol. 3, No I. P.1-11. doi:10.12783/ams.2015.0301.01.