CD-R groove measurement by phase stepping interferometry

The interferometric CD-R groove measurements in transmission and reflection mode with He–Ne and Ar⁺ lasers are presented. The phase micro-inhomogeneities on the surface relief of polycarbonate substrates are compared with the surface relief of a stamping onto copper layer metal master for rainbow holograms, used as a test object. The grid density of the test object is about 60% higher than the density of the CD-R groove at a similar relief depth. The reason for the phase inhomogeneities is due to the refractive index variations of the polymer substrate. The RMS of the measurements is not higher than 0.1 rad.     

锥形轮廓亚波长二维表面浮雕结构的矢量衍射特性

本文利用严格耦合波理论对多台阶逼近锥形轮廓的亚波长二维表面浮雕结构进行了计算分析.从本文的计算结果来看,采用多台阶来逐步逼近锥形轮廓的亚波长零级二维表面浮雕结构具有在宽波段、大视角上能够实现抗反射,并且对光波的偏振态下不敏感的特性.从而使得该结构为薄膜光学在材料的选择方面提供了极大的选择自由度.     

Features in atomic force microscopy studies of dielectric surfaces

To improve the accuracy of AFM measurements in air and the reproducibility of results, a clean room-based metrological facility has been designed and built. The main function of the facility is to control temperature and humidity in an operation zone in various combinations and to maintain them with high accuracy. Measurements under controlled conditions are particularly important for dielectric materials. It has been shown that special procedures allow one to avoid disturbances caused by static charges on the surface under study, i.e., to remove the already accumulated charge and prevent its appearance during experiments. The use of the proposed procedures makes it possible to adequately study the features of the dielectric surface relief at micro-and nanoscale levels.     

Surface relief grating formation in luminescent dye doped photochromic polymer containing azobenzene side groups

We study the formation of a surface relief grating and photoluminescence in a thin layers of a photochromic polymer doped with the luminescent dyes 3-(1,1-dicyanoethenyl)-1-phenyl-4,5-dihydro-1H-pyrazole and Rhodamine 6G. Surface topography measurements via Atomic Force Microscopy confirmed the existence of a surface relief grating with amplitudes as high as 650 nm both for doped and undoped photochromic polymers. Spectroscopic measurements carried out for polymers containing luminescent dyes have shown efficient photoluminescence and amplified spontaneous emission which is characteristic for gain media.     

Study of the structural perfection and distribution/redistribution of silicon in epitaxial GaAs films grown by molecular beam epitaxy on (100), (111)A, and (111)B substrates

Silicon distribution before and after thermal annealing in thin doped GaAs layers grown by molecular beam epitaxy on (100)-, (111)A-, (111)B-oriented substrates is studied by X-ray diffraction and SIMS. The surface morphology of the epitaxial films inside and outside an ion etch crater that arises during SIMS measurements is studied by atomic force microscopy. Distinctions in the surface relief inside the crater for different orientations have been revealed. Observed differences in the doping profiles are explained by features of the surface relief developing in the course of ion etching in SIMS measurements and by enhanced Si diffusion via growth defects.     

An impulse method of measuring normal impedance at oblique incidence

An experimental method of determining the oblique incidence behaviour of sound absorbing materials is given. The method involves the measurement of acoustic impulses at the surface of an absorbing material and comparing the complex frequency components with those of a reference signal recorded remote from the surface. Amplitude and phase characteristics of the reflected signal are thus obtained and hence the normal impedance of the material is found. Comparison between measurements made by the “surface” method and standing wave tube measurements shows good agreement for normal incidence. However, at very oblique angles of incidence the method is in obvious error, the accuracy being limited by a sphericity effect.     

Impedance measurements around grazing incidence for nonlocally reacting thin porous layers

For locally reacting materials with a constant surface impedance, a classical method based on the work of Chien and Soroka [J. Sound Vib. 43, 9-20 (1975)] for measuring this impedance in situ around grazing incidence is currently used. A generalization of this work to include thin nonlocally reacting materials with a surface impedance noticeably dependent on the angle of incidence is performed. It is shown that the model by Chien and Soroka can be used, though the constant surface impedance must be replaced by the impedance at grazing incidence for the evaluation of the numerical distance. Measurements performed on a thin porous layer using this method are compared with measurements performed using the near-field acoustical holography method [M. Tamura, J. Acoust. Soc. Am. 88, 2259-2264 (1990)]. Other measurements performed on a fibrous layer are in good agreement with the predicted values of the impedance at grazing incidence.     

In situ measurements of surface impedance and absorption coefficients of porous materials using two microphones and ambient noise

An in situ measurement method is proposed for obtaining the normal surface impedance and absorption coefficient of porous materials using two microphones located close to the material without a specific sound source such as a loudspeaker. Ambient environmental noise that does not excite distinct modes in the sound field is employed as the sound source. Measurements of the normal surface impedance of glass wool and rockwool have been made using this method in various sound fields. The repeatability and wide applicability of the method are demonstrated by comparing results of measurements in one room with different noise conditions and in three other environments (corridor, cafeteria and terrace). The assumed diffuse nature of the sound field on the material is validated by using absorption characteristics obtained experimentally at oblique incidence. This method allows simple and efficient in situ measurements of absorption characteristics of materials in a diffuse field.     

Inverse method for determining the depth of nonhomogeneous surface layers in elastic solids from the measurements of the dispersion curves of group velocity of surface SH Waves

In this paper, the variational inverse method for determining the depth of nonhomogeneous surface layers in elastic materials, from the measurements of the group velocity of surface shear horizontal (SH) waves, is developed. The direct problem for a given a priori type of profile of the coefficientc44in(x) (e.g. linear, Gaussian, etc.) is solved. The dispersion curves of phase and group velocity of surface SH waves in nonhomogeneous solids are calculated. Experimental verification of the inverse method has been performed for step profiles (structure of Cu on steel). It is stated that the inverse method based on the measurements of group velocity (for step profile) gives a smaller error in the unknown depth of the surface layer than that resulting from the inverse method based on the measurements of phase velocity of surface SH waves.     

Holographic optical element for laser time-of-flight flow sensor

A novel laser time-of-flight flow sensor has been developed. A specially designed holographic optical element (HOE) constitutes the basis of the optical front end of the sensor. The multifunctional HOE maintains both the transmitting and receiving functions of the optical front end and is designed so that the alignment of the optical system is independent of small changes in the wavelength and temperature. This makes it possible to use a laser diode and makes the optical front end very compact and robust. The HOE is produced as a high-efficiency surface relief grating, thus making a large-scale production through polymer replication possible. The design and fabrication of the HOE is described and the stability of the sensor system is discussed with respect to wavelength variations. Direct calibration measurements on the sensor and test velocity measurements are presented. The sensor is intended for water flow measurements in pipes and can also be used for velocity measurements of solid surfaces.     

Diffraction grating with rectangular grooves exceeding 80% diffraction efficiency

A novel design for a surface relief grating with rectangular grooves is presented. The first reflected diffraction order shows experimentally 84% diffraction efficiency for a metallic grating. The required binary surface relief can be manufactured by using one single microlithographic fabrication step similar to standard processes in microelectronics. Each period of the grating consists of a subwavelength “minilattice” with a variable duty cycle. A theoretical model of the structure is presented and compared to measurements at 10.6 μm wavelength. Applications ranging from deflectors, polarizing beam splitters, variable attenuators to general diffractive components such as kinoforms for laser beam shaping are proposed.     

Extrusions and intrusions in fatigued metals. Part 1. State of the art and history†

Current state and historical progress in experimental and theoretical studies of surface relief appertaining to persistent slip bands (PSBs) and leading to fatigue crack initiation in cyclically deformed metals is presented as a thorough critical overview. A comprehensive inventory of microscopic techniques used for this study is tabulated chronologically with emphasis to their applicability to polycrystals. The most relevant experimental characteristics concerning surface relief evolution, namely the form of extrusions and intrusions in single- and polycrystalline materials, are surveyed. Theoretical models and computational simulations of extrusion and intrusion formation and fatigue crack initiation are critically reviewed.     

Diffraction efficiency of holographic blazed diffraction gratings

Holographic blazed diffraction grating is analysed as a periodic relief of an inclined sinusoidal curve in the shallow profile approximation. Under the condition that the rate of the development is a linear function of the development dose the evolution of the relief during the development is discussed. Theoretical curves of diffraction efficiency are compared with measurements on gratings made by direct holographic method for uv spectral region.     

Effect of the transverse size of a laser-induced plasma torch on material processing

Projection microprocessing of materials by Nd: KGW laser shots (1.06 μm) is considered. Specifically, a practically feasible method of processing transparent materials (sapphire, fused quartz, and glass) by means of a laser-induced plasma is suggested. These materials are marked, in particular, by applying a controllable liquid-crystal mask on them. Also, a relief diffraction grating of period 3 μm is patterned on their surface. The effect of the transverse size of the area illuminated on the processing parameters is studied. It is established that the density and temperature of the laser-induced plasma grow with increasing transverse size of the torch, with the energy density of the laser radiation being the same. The plasma torch reverses the pressure and wavelength dependences of the rate of ablation of transparent materials as compared to those of metals.     

Numerical Analysis of Photoinduced Surface Relief Grating Formation by Particle Method

The time evolution of photoinduced surface relief grating formation on azobenzene polymer films is analyzed by particle method for fluid mechanics. The surface relief grating is grown by using two beams interference with various polarization states numerically and compared with experimental results. The force acted on the dipole by electromagnetic field and surface force are considered as the driving force for photoinduced mass transport. The improved surface tension model is proposed in order to calculate curvature coefficient. The numerical results are coincided with experimental results qualititatively.     

Atomically flat surface preparation for surface-sensitive technologies

Surface-sensitive measurements are crucial to many types of researches in condensed matter physics.However,it is difficult to obtain atomically flat surfaces of many single crystals by the commonly used mechanical cleavage.We demonstrate that the grind-polish-sputter-anneal method can be used to obtain atomically flat surfaces on topological materials.Three types of surface-sensitive measurements are performed on CoSi(001) surface with dramatically improved quality of data.This method extends the research area of surface-sensitive measurements to hard-to-cleave alloys,and can be applied to irregular single crystals with selective crystalline planes.It may become a routine process of preparing atomically flat surfaces for surface-sensitive technologies.     

Nonlinear laser-induced regime of surface-electromagnetic-wave generation and submicron periodic relief during liquid-phase photochemical etching of n-III–V semiconductors

This paper is devoted to an experimental study of the physical processes underlying the phenomenon of laser-induced generation of periodic relief on the surface of n-III–V semiconductors during liquid-phase photochemical or photoelectrochemical etching accompanying the resonance interaction of surface electromagnetic waves (SEWs). The increments of the exponentially increasing amplitudes of the dominant Fourier harmonics of the relief have been measured at the initial (linear) stage of the time evolution of the surface profile. It is proven by comparing the theoretical and experimental results that the mechanism for forming periodic structures that we have proposed is adequate. Ways of monochromatizing the generated relief and controlling the line shape of the surface grating are studied. It is experimentally detected for the first time that the nonlinear stage of the time evolution of the relief is characterized, in accordance with the predictions of the theory developed by the authors, by amplitude and phase oscillations of the first and second Fourier harmonics of the surface profile. It is shown to be possible to generate relief that suppresses specular reflection from the surface. A new nonmasked laser method is developed for forming high-quality submicron relief diffraction gratings, combining a holographic method and a method involving laser-induced relief generation during resonance excitation of SEWs. Diffraction gratings with a period of d=0.24–0.54 μm and a depth of h=0.1–0.2 μm over an area of 0.5×31 cm have been created on an n-InP surface. Zh. éksp. Teor. Fiz. 111, 174–198 (January 1997)     

超光滑表面无损检测轮廓仪

本文所述的超光滑表面无损检测轮廓仪,无需标准参考面;利用双焦干涉作非接触无损检测;利用干涉及电子共模抑制技术可有效地抑制各类噪音;计算机控制测量,即时给出表面粗糙度参数,与WYKO比对,结果吻合。仪器特别适合于均方根值R_q为纳米及亚纳米量级的软质金属材料及膜层表面测试。其横向分辨率为1μm,纵向分辨率为0.1nm。     

Simulation of the relief formation a on an amorphous solid surface under bombardment by medium-energy ions using the method of statistical tests: Case of grazing ion incidence

The formation of a wave-like relief on the surface of an amorphous solid under ion bombardment at a grazing angle of incidence (87.5° from the normal to surface) has been investigated by the method of statistical tests. Collision cascades are calculated within the approximation of binary collisions. The irreversible relaxation of the Wolf-Villain type is used for surface relaxation. It is shown that a wave-like relief is formed if, along with modification of the target surface, modification of the target bulk is taken into account.