Particulars of studying the roughness of substrates for multilayer X-ray optics using small-angle X-ray reflectometry,atomic-force,and interference microscopy

The abilities of standard methods for rough surface investigation are analyzed in case of supersmooth substrates for multilayered X-ray optics. The X-ray specular reflection technique is shown to be the most adequate one. X-ray diffuse scattering and AFM can be applied only in a case of PSD-function calculation and approximation over the entire spectrum range of spatial frequencies.     

Rapid in-process measurement of surface roughness using adaptive optics

We present an in-process measurement of surface roughness by combining an optical probe of laser-scattering phenomena and adaptive optics for aberration correction. Measurement results of five steel samples with a roughness ranging from 0.2 to 3.125 μm demonstrate excellent correlation between the peak power and average roughness with a correlation coefficient (R(2)) of 0.9967. The proposed adaptive-optics-assisted system is in good agreement with the stylus method, and error values of less than 8.7% are obtained for average sample roughness in the range of 0.265 to 1.119 μm. The proposed system can be used as a rapid in-process roughness monitor/estimator to further increase the precision and stability of manufacturing processes in situ.     

Continuous-wave ultrasound reflectometry for surface roughness imaging applications

Background

Measurement of surface roughness irregularities that result from various sources such as manufacturing processes, surface damage, and corrosion, is an important indicator of product quality for many nondestructive testing (NDT) industries. Many techniques exist, however because of their qualitative, time-consuming and direct-contact modes, it is of some importance to work out new experimental methods and efficient tools for quantitative estimation of surface roughness.

Objective and method

Here we present continuous-wave ultrasound reflectometry (CWUR) as a novel nondestructive modality for imaging and measuring surface roughness in a non-contact mode. In CWUR, voltage variations due to phase shifts in the reflected ultrasound waves are recorded and processed to form an image of surface roughness.

Results

An acrylic test block with surface irregularities ranging from 4.22 μm to 19.05 μm as measured by a coordinate measuring machine (CMM), is scanned by an ultrasound transducer having a diameter of 45 mm, a focal distance of 70 mm, and a central frequency of 3 MHz. It is shown that CWUR technique gives very good agreement with the results obtained through CMM inasmuch as the maximum average percent error is around 11.5%.

Conclusion

Images obtained here demonstrate that CWUR may be used as a powerful non-contact and quantitative tool for nondestructive inspection and imaging of surface irregularities at the micron-size level with an average error of less than 11.5%.     

K9玻璃零件表面粗糙度研究

本文给出了Ｋ９玻璃零件被不同粒度的磨料磨削之后，其表面的轮廓算术平均偏差Ｒａ、微观不平度十点高度Ｒｚ、轮廓最大高度Ｒｙ等数值，使我们对磨削之后的光学零件表面所能达到的粗糙度等级有一个定量的认识。为工艺、设计人员提供了有用的参考数据。     

显微成像检测表面粗糙度

介绍了用显微成像检测表面粗糙度的方法。该方法具有直观，操作简单，速度快，非接触无损伤，自动检测等优点。显微成像检测表面粗糙度的原理为：被检测表面通过显微放大，由ＣＣＤ作为接收器，经图像采集卡和微机进行数据采集与处理，计算后得到相应的粗糙度。这种方法用于机械加工表面，喷涂等表面检测，对电化学处理表面，指纹，皮肤，细胞等细微结构的检测更具有优越性。     

On geometric optics and surface waves for light scattering by spheres

A geometric optics approach including surface wave contributions has been developed for homogeneous and concentrically coated spheres. In this approach, a ray-by-ray tracing program was used for efficient computation of the extinction and absorption cross sections. The present geometric-optics surface-wave (GOS) theory for light scattering by spheres considers the surface wave contribution along the edge of a particle as a perturbation term to the geometric-optics core that includes Fresnel reflection–refraction and Fraunhofer diffraction. Accuracies of the GOS approach for spheres have been assessed through comparison with the results determined from the exact Lorenz–Mie (LM) theory in terms of the extinction efficiency, single-scattering albedo, and asymmetry factor in the size–wavelength ratio domain. In this quest, we have selected a range of real and imaginary refractive indices representative of water/ice and aerosol species and demonstrated close agreement between the results computed by GOS and LM. This provides the foundation to conduct physically reliable light absorption and scattering computations based on the GOS approach for aerosol aggregates associated with internal and external mixing states employing spheres as building blocks.     

Metal-vapor lasers for problems of atmospheric optics

The paper formulates the requirements for metal-vapor lasers as sources of coherent radiation for atmospheric optics and identifies ways to realize the desired laser performance. Institute of Atmospheric Optics of the Siberian Branch of the Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 88–95, August, 1999.     

Fabrication and application of imaging holographic gratings (chirped gratings) for integrated optics

Holographic chirped gratings with parallel grating lines have been fabricated by recording the interference structure of a plane wave and a cylindrical wave in a photoresist layer on a monomode glass waveguide. These gratings will be useful elements for the imaging of guided waves in integrated optics. A theoretical approach for treating their imaging properties is presented. The experimental results are described theoretically.     

The importance of imaging conditions in scanning tunneling microscopy for the determination of surface texture and roughness

We show that the control conditions in the feedback loop of a scanning tunneling microscope (STM) affect the values of the surface texture parameters, including fractal characterization, when they are calculated from STM images of the surface. The main surface texture parameters (such as the r.m.s. roughness, kurtosis, skewness, and average wavelength) show a strong dependence on the conditions used in the feedback loop for imaging. Fractal character changes also with feedback parameters. The quality of the STM images can be measured quantitatively by using some of the surface texture parameters.     

Laser writing system for fabrication of diffractive optics elements

We report a laser writing system for fabrication of diffractive optical elements with He-Cd laser. The wavelength of the light source is 441.6 nm. The output beam is collimated into parallel light with uniform intensity distribution after passing through the spatial filter with a pinhole of 25μm and the collimating device. A microscopy objective lens with numerical aperture (NA) of 0.65 is used to focus the beam into a small diffraction spot. Any pattern can be written with this system. Experimental results are presented.The written gratings and the phase patterns were verified with a conventional optical microscopy and the Taylor Hobson equipment.     

On the role of scattering by surface roughness in silicon inversion layers

Experimental results are presented, which strongly suggest that scattering of carriers by surface roughness may be important in the silicon inversion layer of metal-oxide-semiconductor structures. Low temperature data for p-type channels on identical orientation at high surface field show that mobility results in this region are dependent only on the mode of sample preparation and are independent of surface charges. The most reasonable explanation for these observations is offered by a scattering mechanism which is closely associated with the surface condition of the SiSiO₂ interface, namely, scattering by surface roughness. This scattering is a direct result of the fluctuating potential caused by the imperfect interface which is only a small distance from the inversion carriers. A calculation of the effect of surface roughness on surface carrier mobility is also given and found to be in satisfactory agreement with the experimental results. The application of the theory to the observed results permits an estimate to be made of the physical dimensions of the surface roughness of the Si-SiO₂ interface.     

Experimental investigation of a flowing fluid layer on metal surface roughness measurement and aberration correction using adaptive optics

The induced optical aberration of laser beam passing through a transparent flowing fluid layer on a metal specimen is experimentally and empirical formula studied. The proposed study presents an experimental investigation of metal surface roughness measurement by combining an optical probe of laser-scattering phenomena and adaptive optics (AO) for aberration correction. In the absence of the AO correction scheme, induced flow velocity of 0.278 m/s can severely degrade the residual wavefront root mean square (RMS) error to 0.58 μm and decrease the scattered laser intensity. Real-time AO correction in closed-loop at a sampling rate of 8Hz can reduce the wavefront RMS error to 0.19 μm and improve the attenuation of scattered laser intensity. The maximum relative error of the estimated roughness (R _a) is less than 7.8% compared with the stylus method. The experimental results show satisfactory correction in the presence of a flowing fluid layer using the AO system.     

Effect of the surface roughness on Bean-Livingston surface barrier

Bean-Livingston barrier for a single Abrikosov vortex interacting with the rough surface is calculated as a function of the random characteristics of the surface roughness. It has been shown that even a respectively smooth surface roughness results in an essential decrease of the Bean-Livingston surface barrier.     

On the effect of microscopic roughness of the metal surface on the surface plasmon dispersion relation and photoemission

The effect of microscopic surface roughness on the opical characteristics of metal is considered. The field near the rough surface has been calculated on the basis of integral equations containing only smoothly varying field components. It appears that the influence of surface plasmons can cause, as a result of drastic enhancement of the field at the surface, an increase by several orders in such observed surface effects as photoemission and Raman scattering by adsorbed molecules. The results of calculation are compared with the experimental data obtained from the study of photoemission from silver with rough surface. Expressions have been derived for the dispersion relation for surface plasmons on a rough surface.     

On the origin of optics

The first optical devices in animals evolved in the Cambrian period. The first reflector known dates from around 508 million years ago (Ma); the first eyes with lenses evolved at around 521 Ma. Consideration of the introduction of vision leads to a hypothesis for the cause of evolution's Big Bang—the Cambrian explosion. Suddenly, and for no obvious reason, the range and variety of life-forms erupted somewhere between 520 and 515 Ma (as limited by of our dating techniques). At no other time in Earth's history there has been such a profusion, such an exuberance, and such an overwhelming diversity in so short time, within one million years. Prior to this Cambrian explosion event, all animals were soft-bodied and mainly worm-like, as they had been for millions of years before that. But during the Cambrian explosion many of the major animal groups on Earth today independently evolved their hard body parts for the first time. Following the appearance of the first trilobites, some animals evolved shells and spines, some with bright colours, to visually warn of their new armour. Others evolved streamlined appearances and swimming oars to advise trilobites that they could not be caught. The Light Switch Theory provides an explanation for what triggered this event—that it was the development of vision (in trilobites); the introduction of optics. Once visual capability arose, it allowed predators to identify prey, triggering an arms race. From here on, vision became a dominant force of evolution and resulted in the eyes and reflecting optics that we have in nature today. This paper provides a summary of the first optical devices to evolve in animals, along with the implications of these in their relevance to the Big Bang of evolution, written for the physical sciences.     

Digital speckle interferometry for assessment of surface roughness

In this work, the principle of interferometry is used to assess the surface roughness of the machined surfaces. Interferometry produces an interference fringe pattern when two or more light waves interact with each other. It is one of the important tool for precision optical metrology and testing. Well-known advantages of the phase shifting interferometry include high measurement accuracy, rapid measurement, good result even with low contrast fringes and that the polarity of the wave front can be determined. In fringe projection techniques, a known optical fringe pattern is projected onto the surface of interest. The fringe pattern on the surface is perturbed in accordance with the profile of the test surface, thereby enabling direct derivation of surface profile.In this work, an attempt has been made to assess the surface roughness using a speckle fringe analysis method of five frame phase shift algorithm for machined surface (ground surface). As these fringes are too noisy, advanced filtering technique has been used so as to reduce noise and to get improved wrapped phase map from the phase shifted fringes. A phase unwrapping software has been developed using discrete cosine transform (DCT) to generate the three-dimensional (3-D) profiles. Finally, it is compared with R_a values measured using a mechanical stylus instrument, showing good agreement.     

A novel technique of laser measurement for the surface roughness

This paper describes a non-contact system for the surface roughness measurement without damage. It is suitable for various materials.     

A technological complex for manufacturing of precise imaging optics

A comprehensive approach to solving the problem of creating supersmooth optical surfaces with subnanometer accuracy is described. In this work, we create a production process that includes the certification of optical elements, finishing shapes to the required parameters while preserving the atomic smoothness of the surface, and the deposition of multilayered reflecting coverings with internal stresses compensated for.