Jean M. Bennett

Bio: Jean M. Bennett is an academic researcher from Uppsala University. The author has contributed to research in topics: Surface roughness & Scattering. The author has an hindex of 18, co-authored 43 publications receiving 2558 citations.

Relationship of the total integrated scattering from multilayer-coated optics to angle of incidence, polarization, correlation length, and roughness cross-correlation properties

Abstract: Previously published vector equations describing angle-resolved scattering from single-layer- and multilayer-coated optics have been integrated numerically and analytically over all angles in the reflecting hemisphere to obtain numerical results and analytical expressions for total integrated scattering (TIS). The effects of correlation length, polarization, angle of incidence, roughness height distribution, scattered light missed by the collecting hemisphere, and roughness cross-correlation properties of the multilayer stack on the TIS expression are considered. Background material on TIS from optics coated with single opaque reflecting layers is given for completeness and comparison to corresponding multilayer TIS results. It is shown that errors can occur in calculating the true rms surface roughness from actual TIS measurements; ways to correct these errors are discussed.

Comparison of the properties of titanium dioxide films prepared by various techniques.

Abstract: Fourteen university, government, and industrial laboratories prepared a total of twenty pairs of single-layer titanium dioxide films. Several laboratories analyzed the coatings to determine their optical properties, thickness, surface roughness, absorption, wetting contact angle, and crystalline structure. Wide variations were found in the optical and physical properties of the films, even among films produced by nominally the same deposition techniques.

Multiple determination of the optical constants of thin-film coating materials

Abstract: The seven participating laboratories received films of two different thicknesses of Sc2O3 and Rh. All samples of each material were prepared in a single deposition run. Brief descriptions are given of the various methods used for determination of the optical constants of these coating materials. The measurement data are presented, and the results are compared. The mean of the variances of the Sc2O3 refractive-index determinations in the 0.40–0.75-nm spectral region was 0.03. The corresponding variances for the refractive index and absorption coefficient of Rh were 0.35 and 0.26, respectively.

Measurement of the rms roughness, autocovariance function and other statistical properties of optical surfaces using a FECO scanning interferometer.

Abstract: A brief review of techniques for measuring surface roughness and optical figure is given. One of the most promising of these techniques for measuring the roughness of optical surfaces is interferometry employing fringes of equal chromatic order (feco). A feco scanning interferometer is described, which has been used to determine statistics of polished surfaces having roughnesses under 100 A rms. The scanning interferometer resolves square surface elements 2 μm on a side and statistically characterizes the surface in terms of these elements. Height- and slope-distribution functions, rms roughness, rms slope, and modified autocovariance length distributions have been measured for selected optical surfaces. Nearly all surfaces had Gaussian distributions of heights and slopes, but none had Gaussian distributions of autocovariance lengths. Surfaces such as electropolished copper, electroless nickel, and single-point diamond-machined copper were found to have smaller rms slopes than other surfaces of comparable roughness and scattered less than predicted by simple scalar scattering theory.1,2 On the other hand, heavily scratched surfaces such as polished potassium chloride had larger slopes and produced more scattering than expected from simple theory.

Atomic force microscope

Abstract: The scanning tunneling microscope is proposed as a method to measure forces as small as 10-18 N. As one application for this concept, we introduce a new type of microscope capable of investigating surfaces of insulators on an atomic scale. The atomic force microscope is a combination of the principles of the scanning tunneling microscope and the stylus profilometer. It incorporates a probe that does not damage the surface. Our preliminary results in air demonstrate a lateral resolution of 30 A and a vertical resolution less than 1 A.

Caractérisation des surfaces par réflexion rasante de rayons X. Application à l'étude du polissage de quelques verres silicates

Abstract: La theorie presentee permet d'obtenir une formulation explicite de l'influence des rugosites ainsi que des variations locales de constante dielectrique n2 (dues par exemple a une modification de composition ou de compacite) sur la reflexion rasante d'un faisceau de rayons X monochromatique, dans la mesure ou les rugosites relevent d'une distribution gaussienne et a condition que n2 ne depende que de la profondeur Z par rapport au plan moyen de la surface eclairee. L'analyse des verres silicates polis mecaniquement sur polissoir en poix, a l'aide de suspensions aqueuses d'oxydes divers, revele que la couche de polissage se compose en realite de deux zones bien distinctes. La premiere, tout a fait superficielle, l'epaisseur ne depassant pas quelques dizaines d'angstroms, presente une densite toujours inferieure a celle du coeur de l'echantillon et semble imputable au fluage plastique et a l'hydrolyse de la surface pendant le polissage. La seconde, sous-jacente, s'etend au contraire sur plusieurs centaines d'angstroms et met en jeu un processus soit de densification (silice pure, alumino-silicate) soit de lacunisation (verres a assez forte teneur en ions alcalins). Nous examinons egalement l'influence de la duree du polissage, du type d'oxyde utilise, et (ou) des traitements thermiques effectues apres polissage, sur les divers parametres qui caracterisent ces couches.

Surface reflection: physical and geometrical perspectives

Abstract: Reflectance models based on physical optics and geometrical optics are studied. Specifically, the authors consider the Beckmann-Spizzichino (physical optics) model and the Torrance-Sparrow (geometrical optics) model. These two models were chosen because they have been reported to fit experimental data well. Each model is described in detail, and the conditions that determine the validity of the model are clearly stated. By studying reflectance curves predicted by the two models, the authors propose a reflectance framework comprising three components: the diffuse lobe, the specular lobe, and the specular spike. The effects of surface roughness on the three primary components are analyzed in detail. >

Anti-reflecting and photonic nanostructures

Abstract: Optical reflection, or in other words the loss of reflection, from a surface becomes increasingly crucial in determining the extent of the light-matter interaction. The simplest example of using an anti-reflecting (AR) surface is possibly the solar cell that incorporates an AR coating to harvest sunlight more effectively. Researchers have now found ways to mimic biological structures, such as moth eyes or cicada wings, which have been used for the AR purpose by nature herself. These nanoscopic biomimetic structures lend valuable clues in fabricating and designing gradient refractive index materials that are efficient AR structures. The reflectance from a selected sub-wavelength or gradient index structures have come down to below 1% in the visible region of the spectrum and efforts are on to achieve broader bands of such enhanced AR regime. In addition to the challenge of broader bands, the performance of AR structures is also limited by factors such as omnidirectional properties and polarization of incident light. This review presents selected state-of-the-art AR techniques, reported over the last half a century, and their guiding principles to predict a logical trend for future research in this field.

Atomic Resolution with Atomic Force Microscope

Abstract: The atomic force microscope (AFM) is a promising new method for studying the surface structure of both conductors and insulators. In mapping a graphite surface with an insulating stylus, we have achieved a resolution better than 2.5 A.