At the beginning of this opening lecture I would like to present some general comment concerning light. As we well know, light is an element in nature which has very deep interrelations with our life from a biological and psychological point ofview. The detailed studies ofvarious languages and religions show a very large role played by the word "light". In the texts of the Old or New Testaments and Koran one finds many times the word "light" having various meanings. A well known example is: "God divided the light from the darkness" (The Old Testament, Genesis 1.4). In all languages the word "light" has not only a physical or technical meaning, and there exist many expressions having various specific meanings. In English, for instance, there are the physical or technical expressions like tail light, flash light, traffic light,... and many others. On the other hand, there are such expressions as: in the light of, to bring to light, to come to light, men of light and leading, by the light of nature, light in the head, out like a light... (see, for example, The Oxford English Dictionary).

In the wave diffracted by a hologram, geometrical and boundary waves may be distinguished despite the diffraction character of this wave. The boundary wave is directly related to the shape of amplitude distribution in object image point. The imaging by means of the small holograms deserves a particular attention. The losses of information connected with diminishing hologram size are closely related to high value of the boundary wave. This fact is essential when the holograms are to be coupled with the systems of integrated optics.

Image processing and recognition methods are useful in many fields. According to situation, different techniques are used. For many years, methods based on optical Fourier transformation were very popular. Image recognition was performed generally by using optical correlators. Correlation techniques were strongly developed especially for military applications, but in many cases (industrial, biological and biomedical applications) these techniques suffer from a number of limitations. For these reasons, methods based on extraction and statistical processing of image features are more useful. Set of features can be extracted directly from an image (features based on image morphology, image moments etc.) or from image transforms (Fourier, Radon, Hough, Sine, Cosine etc.). The Fourier transformation is one of the most important in image processing. It can be simply performed by using an optical diffractometer. It allows to build image descriptors independent on image translation and after processing independent on image rotation. Diffractometers are very convenient in industrial and medical applications. Digital image processing and recognition were strongly developed on powerful workstations, however these procedures can also be implemented in PCs with DSP microprocessor cards or in situations where digital transforms used for image processing can be simply implemented and do not consume a lot of time. The example of biomedical image recognition performed in an optical way, by using a diffractometer, and in a digital system with a CCD camera will be described here.

A band-pass filtering technique has been used in an automated system for detection of early stages of cervical cancer. Practical difficulties of the system and measures taken to overcome them are outlined. A special section is devoted to coherent noise suppression techniques. Some of these methods may be put into real use in many other applications of optical filtering.

This paper presents a simple technique of phase retardation measurement applied to phase object manufacturing. This method is based on computer aided analysis of diffraction pattern generated by phase object. Application of this method to known intensity distribution in Fourier spectrum allows to find phase distribution in an object. The method is especially aligned for techniques where an unknown phase modulation is gained by the exposure of a photosensitive media. The described method can help to predict the desired phase shift from exposure. The phase retardation measurement technique presented in this paper is especially aligned to the problem of Holographic Optical Elements (HOE) manufacturing.

The present approach to the diffractive element design is based on Kirchhoff scalar theory of diffraction. Predictions made by this theory become unreliable if the diffraction of polarized light is evaluated. The paper presents the 'vector correction' to the Kirchhoff theory and suggest a method for calculating interaction of diffractive optical element and an incident electromagnetic field.

Quasi-stationary states of formed relief dynamic grating are studied for temperature mechanisms of grating growth. Phenomena of optical bistability, increasing, decreasing and stabilization of steady state dynamic grating height is defined. An experimental study of the resonant relief dynamic gratings using a diffractometric technique and germanium samples is carried out. The effects of grating height increasing, instability as well as generation of higher order nonlinear gratings were observed, all being caused by an influence of the surface polaritons excitation on the gratings growth.

The instrument for measuring the light scattered from optical surfaces is described. The measurement is carried out using the 253 nm wavelength separated from continuous spectrum of high pressure mercury lamp by a double monochromator. Output signals are detected by a photomultiplier whose sensitivity falls rapidly above 300 nm. The sensitivity of the instrument is about 0.5/3 X 10<^8%, where the numbers 0.5 and 3 X 10⁸ characterize the minimal detectable output signal and the maximal one (in reflected light).

The convolution method of solution of some problems in scalar diffraction for optical multicomponent systems including ones based on the Talbot or Lau effect is described. This work is a development of ideas of the diffraction theory treatment suggested by Cowlew and Hoodie. As example, the developed method has been applied to a double- grating system for which three configurations are found and investigated.

Diffraction and interference of light produced by two phase holographic gratings are investigated. The phase copies of original amplitude holograms are used. Two original holograms are recorded with the same interferometer's optical system, but one of them is obtained with the phase object in question and the other without. By illuminating two phase holographic gratings by a wide light source, the interference patterns were obtained in the first and zero diffraction orders. The mutual-additional interferograms were obtained experimentally. One must notice that the aberrations from the optical system are compensated for.

Generalization of the linear matched filter concept to nonlinear matched filter is presented. It is shown that the nonlinearity introduced in the filter domain results in the component of the diffraction hologram structure which is associated with a whole set of a joint power spectrum for mutually incoherent (noninterfering) input signals. It is shown that a correlator with a holographic match filter whose amplitude transmittance expanded in powers of exposure contains up to and including second order terms (the so-called 'second order hologram') is a new class of 2D or 3D optical associative memories.

Principle, main advantages and applications of acousto-optic spectral devices with dynamic refractive index grating are reviewed.

The possibilities of employment asymmetric diffraction patterns for testing microdisplacements and refractive index of transparent objects.

The laser diffraction on the inclined narrow slit with the final thickness edges is investigated experimentally and theoretically. One should notice that Fresnel's diffraction integral is not correct for this case and it is necessary to take into account the repeated reflections of the laser radiation.

Methods for measurement of optical fibers and wires diameters, data processing and experimental results are presented. The charge-coupled devices line array as a detector for reading one dimensional diffraction images was applied. Experimental results showed that diameters of optical fibers can be measured with 1% accuracy and wires with 0.5% accuracy. The described method can be apply to industry control measuring device working on line.

We describe experimental measurements of the scattering properties of two conducting surfaces with 1D roughness. The surfaces have been fabricated in photoresist and have been characterized with a stylus that is small compared to the surface correlation length. In studies of diffuse scatter, we present measurements of the four unique elements of the Stokes matrix. Backscattering enhancement and associated polarization effects are observed for the rougher surface while behavior consistent with tangent plane models is seen for the smoother surface. The polarization-dependence of the coherent scatter is also investigated, and comparisons are made with the results calculated for a flat surface. Finally, we briefly present results for the angular correlation functions of intensity, where the coherent effects that produce backscattering enhancement are more directly observed.

The problems of how optical techniques, i.e., luminescence and optical reflectivity measurements, and how the reflection high energy electron diffraction method may be used for studying the surface and interface roughness of semiconductor structures grown by molecular beam epitaxy (MBE) are reviewed. Luminescence spectroscopy is presented as a post- growth measurement technique used for analysis of the structural disorder occurring during the growth process at the interfaces of quantum well heterostructures. Optical reflectivity techniques are descussed from the point of view of monitoring in situ the growth rate, the roughness and the chemical inhomogeneity of the solid surfaces which grow epitaxially in the MBE crystallization system. The reflection high energy electron diffraction (RHEED) technique is presented and shortly discussed as the in situ controlling technique, most frequently used in MBE processes. The paper is concluded with an outlook indicating the current trends in applying optical techniques for studying and controling surfaces and interfaces of MBE grown semiconductor structures.

Confocal imaging of rough surfaces is considered. The general principles apply not only to confocal systems but also to other interferometric systems using high aperture objectives or a broad band of illumination wavelengths. It is demonstrated that scattering by a rough surface can be described in terms of its 3D spectrum and the coherent transfer function of the imaging system. An effective transfer function for imaging of rough surfaces is developed, based on the Kirchhoff approximation. It is described how confocal imaging can be used for reconstruction of surface profiles in the Kirchhoff approximation.

The relationship between statistical structure parameters of rough surface and associated correlation parameters of scattered field is used to develop the methods for rough surface diagnostics. The treatment is based on the model of random phase object with inhomogeneity phase dispersion. The proposed diagnostic method is applicable to plane and spherical verysmooth surfaces. The sensitivity limit of the method in measuring the standard deviation of surface profile from base line is about 0.003 micrometers .

An instrument for measuring the roughness of optical surfaces was recently built in the Institute of Applied Optics. It is especially useful for testing highly polished surfaces of glass, silica, metals and for visualization of digs, scratches, surface microirregularities and dust particles. Results are compared with the rms surfaces roughness obtained by phase-stepping Differential Interference Contrast (DIC) technique and Total Integrated Scattering (TIS).

In this paper a method and an instrument worked out for evaluating roughness of machined surfaces are presented. The main idea of the method is to light up surface by laser beam and then to record an angular distribution of intensity of scattered light. Based on angular distribution of scattered light some parameters and characteristics of surface roughness are determined. This instrument can be used for measurements of flat and rotary surfaces. The application of the instrument is in the fields of full automatic testing, nondestructive testing and continuous process control.

The roughness of the electrode onto which the Surface Enhanced Raman Scattering (SERS) occurs may be changed by variation of parameters of the oxidation-reduction procedure, whereas the atomic scale roughness of an electrode may be altered by variation of the electrode potential, its temperature as well as by illumination. Variations of both mentioned types of roughness cause changes of SERS signal. These changes prove for the electromagnetic and chemical origin of the enhancement in the SERS phenomenon.

A new approach of speckle displacement analysis by quasi phase correlation measurement is described. An optical implementation of the method based on one focal length correlator architecture using a liquid crystal light valve is proposed.

We show that collective Cotton-Mouton (C-M) effect can be used to determine the anisotropic orientational arrangement of molecules within scattering centers such as colloid and suspension particles. The technique applied to liquid-crystal suspensions indicates that both smectic-nematic and nematic-isotropic transitions can be easily determined within mesogenic droplets. The measurements were performed on mesomorphic 4-cyano-4'-(n-octyl) biphenyl having both smectic A and nematic phases. Using the generalized nth order Langevin's functions L(subscript n%/, the statistical model is presented for the collective C-M effect in the monodisperse suspensions of smectics and nematics.

Sodium clusters were produced in the stainless steel cell with the aid of the laser light. As they did not exhibit any resultant velocity, mass spectrometry methods were not applicable. Optical scatterometry was find useful. The processes of cluster growth and decay were investigated as well as the spatial distribution of the density of clusters. Data on the cluster size and dynamics were obtained. The appearance of the acoustic shock wave after the rapid laser switch on was detected.

Scattering and absorption of visible and infrared light by mirror surfaces covered with condensed layers of residual gas particles have been examined. Such examinations are important in modeling threshold conditions for operation of telescopes, radiometers, and other space instruments.

Although N₂, O₂, Ar, Ne and air, regardless to phase state, are transparent to radiation over wide spectral range, their appearance in a condensed state at an optical surface leads to partial losses in the mirror component of the directed ray flux due to scattering.

Scattering of light by damage and contamination of external optical surfaces of space instruments was examined and some relations between the frequency contrast characteristics and scattering coefficient have been established.

Raman investigations of Peierls-Hubbard (TTF⁺)₂ dimers in (TTF)₂Mo₆O₁₉ and (TTF)₂W₆O₁₉ salts have been performed. It was found, that the resonance enhancement of Raman intensity of intramolecular vibration modes exists only when the frequency of exciting light fits to the localized electron transition, however, the resonance enhancement of intermolecular modes occurs when the frequency of exciting light corresponds to the charge transfer transition.

A series of experiments with light scattering by eye lenses were carried out. The light scattered by a whole lens was examined and information about the state of various parts of the lens was obtained. On the other hand the unscattered component of light passing through a lens was measured as temperature is lowered towards the phase separation point. The aim of the analysis that follows is to establish experimental methods, which would allow one to evaluate an eye lens state and measure the degree of cataract development. Finally, the results of the both techniques are compared.

The results of goniometric investigations of laser light scattered by bone samples are presented. Measurements were performed on macerated, full-thickness skull samples. The angular dependence of the intensity of laser light scattered by the samples was measured. The transmission of light through the samples was evaluated as a function of the wavelength of incident radiation.

The last 25 years of activity of the Wasaw Institute of Applied Optics (Instytut Optyki Stosowanej - IOS) (formerly Central Optical Laboratory) in diffractometry and scatterometry is presented. The methods of investigations and different types of apparatuses (especially diffractometers) developed in IOS are described. Examples of practical applications of diffractometry and scatterometry are shown.

The results presented in the report are related to a series of investigations carried out at the Department to Hydro-optics of SOI during a number of years with the aim of development, design and practical employment of optical instruments of measuring the statistical characteristics of turbulent inhomogeneities in sea water. The values if magnitude and characteristics scales of refractive index fluctuations caused by turbulent convection in sea water with temperature and salinity stratification, as well as the presence of suspended hydrosol particles, stipulate the choice of devices based on photoelectrical registration of small-angle scattering of light beam propagating through the volume of analyzed medium. The developed modifications of phase- contrast methods (shadow methods) make it possible to detect the variations of light beam angle-of-arrival at the level of 0.03" - 0.05"; the instrument may be mounted on remotely controlled underwater carrier towed by research vessel with the velocity 4-12 knots at the desired depth in the range from 0 to 300 m. The interpretation of registered signals from photoelectrical output of the optical instrument is based on the connection between the signal correlation function or spectrum and the energetic spectrum of refractive index fluctuations. The corresponding relations are obtained with the help of the theory of light propagation in random media, namely, the closed equations for light field statistical moments in parabolic approximation. The results of theoretical analysis allows the optimization of optical scheme to meet the requirements of linearity of the signal relation to the analyzed fluctuations magnitude, high spatial resolution and low sensitivity threshold, as well as sufficient resistance to vibrations and changes in pressure and temperature. A measurement of optical fluctuations spectrum in turbulent flow behind a heated grating in hydrodynamic tube are shown to demonstrate the designed instruments abilities. Some results of in-situ experiments made in calm waters and in turbulized layer near thermocline are presented.

Laser scattering by biopolymers and biotissues is studied the Stokes polarimetry method which permits obtaining exhaustive information on the changes in photometric and polarization characteristics of laser radiation resulting from scattering by various kinds of biological structures. Spatial and angular dependencies of scattering matrix elements are studied for albumin, lysocim mycopeptide, muscle and skin tissues, etc. The relative magnitudes of scattering indicatrices are found to be different for different biological objects. Is shown that the objects studied have the property of transformating the type and form of polarization of the incident laser beam. The fraction of depolarized radiation within the polarimeter field of view is shown to increase with the number of scattering events. The results obtained can be useful in developing noncontact methods for assessing the structures of biological tissues.

Physical principles underlying the original noncontact optical-correlation techniques for surface diagnostics are discussed. The performance of the optical correlation devices is compared with that of the available diagnostics systems. The proposed systems for surface diagnostics are based on the relationship between the statistical parameters of the object's structure and the associated correlation parameters of the scattered optical field. The relationship is used in developing diagnostic systems based on the scintillation index, the transverse correlation function, the amplitude variance and the field phase measurements '.The advantage of the proposed systems is the high speed (1.2 seconds) operation which is achieved by performing the statistical data processingwithin the optical channeL The height parameter measurement accuracy is 25 A.

Necessity of supersmooth optical radiation transparent surfaces and laser mirrors with minimum losses through scattering creation required the subsequent development of refiectometric nondestructive surface roughness measurement methods. There are the scalar theory of reflectivity from rough es' and the vector theory 2 have been worked out in the present time. The last of them takes in account interaction of the electromagnetic radiation with surface electrons and influence of the reflectivity material constants. There is the comparative analysis of the scattering light spatial distribution measurement methods given in this paper. The reflectivity radiation diffusion component is examined as a function of the statistical parameters root mean square (rms) surface roughness a, autocovariance length of the surface a and root mean square microfacet pitch tg y = a/a. There is the optical radiation transparent measurement method3 discussed in this work. The results of this measuring method for supersmooth surfaces were compared with theory and ones obtained with other methods and it was received good agreement. The connection of the scattering indicatrix with the parameters of the high quality laser mirrors has been described in this work. The methods which allow to measure back scattering and scattering "in mode" and influence this differential scattering to the interferometrical measurement devices parameters are discussed.

Necessity of supersmooth optical radiation transparent surfaces and laser mirrors with minimum losses through scattering creation required the subsequent development of refiectometric nondestructive surface roughness measurement methods. There are the scalar theory of reflectivity from rough es' and the vector theory 2 have been worked out in the present time. The last of them takes in account interaction of the electromagnetic radiation with surface electrons and influence of the reflectivity material constants. There is the comparative analysis of the scattering light spatial distribution measurement methods given in this paper. The reflectivity radiation diffusion component is examined as a function of the statistical parameters root mean square (rms) surface roughness a, autocovariance length of the surface a and root mean square microfacet pitch tg y = a/a. There is the optical radiation transparent measurement method3 discussed in this work. The results of this measuring method for supersmooth surfaces were compared with theory and ones obtained with other methods and it was received good agreement. The connection of the scattering indicatrix with the parameters of the high quality laser mirrors has been described in this work. The methods which allow to measure back scattering and scattering "in mode" and influence this differential scattering to the interferometrical measurement devices parameters are discussed.

An optical correlation method is proposed for determining concentration and size distribution of light scattering particles by measuring the transverse coherence function of the particle image. The correlation function of a polydisperse ensemble of particles will then be given by an integral equation in the form of a convolution of the transverse correlation function of single particle image with a particle size distribution function. The transverse correlation function of a spherical particle with a radius obtained by an interference measurement, is in turn determined by the amount of overlap of the superimposed particle images. The integral equation can be solved using the regularization method with the minimalization of the functional. A device for measuring particle size distribution functions is proposed which has a response time of about 10 seconds, and can be applied to measure particle sizes ranging from 3 to 500 micrometers with a measurement error about 10%.

Basing on the two-parameter version of the double-flow approximation of radiation transfer theory, known as the Gurevic-Kubelka-Munk theory, absorption and scattering indexes of an elementary volume were defined for polydispersal powder of titan dioxid (anatase) in the spectral range from 2.5 to 12 mkm. For these characteristics determination, reflectivities of thick layers of the investigated powder mixtures with the support powder of the substance with the known refractive index were measured. The monodispersal powder of an oxideless glass was used as the reference. Its particles size exedeed the wavelength of radiation many times. Absorption and scattering indexes of this powder for the elementary volume were calculated by Antonov-Romanovsky formulas. The mixtures of the powders were composed in the definite concentrations. The spectral reflectivities were measured using an apparatus consisting of a IKS-31 spectrometer and an attachment with a hemispherical mirror. During the experiment it was found that the investigated characteristics of the anatase powder in the mid infrared have high spectral selectivity.

Diffraction on metal and semiconductor surfaces during the process of laser irradiation is interesting for microelectronics, power optics and elements of measuring technology. We also present experimental data in changing dynamics of diffuse reflection of copper and bronze mirrors and silicon polished plates during laser irradiation. The impulse of laser radiation from neodymium glass lasts 4 ms. There could be seen the intense reversible increase of diffusion scattering and at the same time decrease of specular component of reflection during laser influence on metal and the appearance of precisely expressed unreturn scattering reflexes during irradiation of semiconductor plates long before the melting threshold. We conduct the quantitative measurements of target thermodeformation, local deformation of heterogeneities and laser induced effects of the surface with the help of the impulse two.beam interferometry method by indirect measurements of temperature in laser radiation zone. We also established the connection between the dynamic change of scattering of metal and semiconductor with the nature of deformation, such as thermo..deformation of the whole irradiation zone, local deformation of heterogeneities of the surface and defects generated by laser. A physical model of laser induced surface roughness, confirmed by mathematical calculations in the thermoelastic approach, will be also discussed.

Efficient generation ofwaveguide modes and exponential increaseof optically induced gratings can take place under the scattering of laser radiation on a rough surface of semiconductor or insulator. In this paper, the following non-stationary self-consistent problem is considered. Laser radiation generates waveguide modes and interferes with them. Arising interference, thermal source results in thermoelastic deformation determining the amplitude of waveguide modes. Analytical expression for the coefficient of laser radiation transformation into waveguide mode is obtained. An analytical solution for the evolution of dynamic gratings and temperature fields is found. An analysis for this solution shows that the average surface temperature turns out to be constant for large times. The periodical temperature profile and dynamic grating either increase or decrease exponentially depending on relation between the space frequency of initial surface roughness and the threshold frequency determined by the parameters of the solid and laser radiation intensity.

An spectrum of a scattering radiation differs from that of radiation falling on a medium. In the case of the single scattering the radiation spectrum is defmed completly with regularities of elementary volume light scattering. In the case of multiple scattering the optical thickness of the scattering medium layer essentially influence on radiation spectrum. On the one hand, light scattering characteristics of layer depend on changes of elementary volume absorption a and scattering a indexes connected with wavelength changes, particulary due to the changes of indicartix of diffusion and refractive index dispersion. On the other hand, the light scattering characteristics of layer depend on the number of scattering actes, that, in turn, depends particulary on the geometrical thickness of the layer. For describing a sick absorption substances with /9 =a/a << 1 and with any indicatrix of diffusion the Rosenberg's arbitrary scattering approximate theory gives good results. Using this theory niultiple scattering radiation spectra for visible region were calculated for the radiation passed through layers of different optical thickness — from small one to thicknesses suitable to the establishment of the depth asymptotic regime. The researches were made for model media in the visible region of the spectrum. The influence of all parameters of elementary volume on the spectrum of passed radiation has been searched. As a result it has been received that in cases of small optical thicknesses (when the single scattering is realized) short-vawe radiation prevalences in scattering light, and in cases of large optical thicknesses — longwave one. Variations of A lead to changes of indicatrix of diffusion of elementary volume. For example, with increasing of A the isotropic indicatrix becames the anisotropic one. The radiation spectra passed through scattering medium into different directions change by different manners. As the depth regime is realized, the spectrum of the passed radiation optical density is formed only with the spectral characteristics of the elementary volume and does not depend on its indicatrix of diffusion and the geometrical thickness of the layer. The results of the calculations are adjusted with the experiments made on the light scattering optical glasses