An ellipsoidal mirror for focusing neutral atomic and molecular beams

Manipulation of atomic and molecular beams is essential to atom optics applications including atom lasers, atom lithography, atom interferometry and neutral atom microscopy. The manipulation of charge-neutral beams of limited polarizability, spin or excitation states remains problematic, but may be overcome by the development of novel diffractive or reflective optical elements. In this paper, we present the first experimental demonstration of atom focusing using an ellipsoidal mirror. The ellipsoidal mirror enables stigmatic off-axis focusing for the first time and we demonstrate focusing of a beam of neutral, ground-state helium atoms down to an approximately circular spot, (26.8±0.5) μm×(31.4±0.8) μm in size. The spot area is two orders of magnitude smaller than previous reflective focusing of atomic beams and is a critical milestone towards the construction of a high-intensity scanning helium microscope

An ellipsoidal mirror for focusing neutral atomic and molecular beams

Manipulation of atomic and molecular beams is essential to atom optics applications including atom lasers, atom lithography, atom interferometry and neutral atom microscopy. The manipulation of charge-neutral beams of limited polarizability, spin or excitation states remains problematic, but may be overcome by the development of novel diffractive or reflective optical elements. In this paper, we present the first experimental demonstration of atom focusing using an ellipsoidal mirror. The ellipsoidal mirror enables stigmatic off-axis focusing for the first time and we demonstrate focusing of a beam of neutral, ground-state helium atoms down to an approximately circular spot, (26.8±0.5) μm×(31.4±0.8) μm in size. The spot area is two orders of magnitude smaller than previous reflective focusing of atomic beams and is a critical milestone towards the construction of a high-intensity scanning helium microscope

Poisson's Spot with Molecules

In the Poisson-spot experiment, waves emanating from a source are blocked by a circular obstacle. Due to their positive on-axis interference an image of the source (the Poisson spot) is observed within the geometrical shadow of the obstacle. In this paper we report the observation of Poisson\u2019s spot using a beam of neutral deuterium molecules. The wavelength independence and the weak constraints on angular alignment and position of the circular obstacle make Poisson\u2019s spot a promising candidate for applications ranging from the study of large molecule diffraction to patterning with molecules

An ellipsoidal mirror for focusing neutral atomic and molecular beams

K. Fladischer et al.Manipulation of atomic and molecular beams is essential to atom optics applications including atom lasers, atom lithography, atom interferometry and neutral atom microscopy. The manipulation of charge-neutral beams of limited polarizability, spin or excitation states remains problematic, but may be overcome by the development of novel diffractive or reflective optical elements. In this paper, we present the first experimental demonstration of atom focusing using an ellipsoidal mirror. The ellipsoidal mirror enables stigmatic off-axis focusing for the first time and we demonstrate focusing of a beam of neutral, ground-state helium atoms down to an approximately circular spot, (26.8±0.5) μm×(31.4±0.8) μm in size. The spot area is two orders of magnitude smaller than previous reflective focusing of atomic beams and is a critical milestone towards the construction of a high-intensity scanning helium microscope.This work was supported by the European Commission, FP6, through the NEST ADVENTURE program, Project INA, Contract Number 509014. Further support was provided by the Polish Ministry of Education and Science.Peer reviewe

An optical profilometer for characterizing complex surfaces under high vacuum conditions

The requirements for high precision metrology devices have increased rapidly in recent years. Furthermore, the applications are spreading to many new branches of science and technology. Hence new demands are appearing which are related not only to classical parameters such as precision and speed but also to other factors including the environment in which the measurements must be performed. In this paper we present a new device for measuring complex surface profiles of samples held under high vacuum conditions. The surface profile is obtained by scanning an optical sensor, held in air, across a standard view-port. The sensor has a lateral resolution of 25 View the μ and a perpendicular distance resolution of 0.12 View the μ over a range of 3 mm. The maximum scanning area is a circle, 30 mm in diameter. The device was developed to characterize silicon wafers for use as mirrors for atom optical applications. The mirrors are formed by bending the silicon under an applied electric field, which requires high vacuum conditions to prevent arc discharge. In the last part of the paper we discuss how simulations can be used to determine the required sampling grid spacing for obtaining the surface profile shape with a given accuracy

Self Catalyzed Growth of Vertically Aligned InN Nanorods by Metal Organic Vapor Phase Epitaxy

Vertically aligned hexagonal InN nanorods were grown mask free by conventional metal amp; 8722;organic vapor phase epitaxy without any foreign catalyst. The In droplets on top of the nanorods indicate a self catalytic vapor amp; 8722;liquid amp; 8722;solid growth mode. A systematic study on important growth parameters has been carried out for the optimization of nanorod morphology. The nanorod N polarity, induced by high temperature nitridation of the sapphire substrate, is necessary to achieve vertical growth. Hydrogen, usuallyinapplicable during InN growth due to formation of metallic indium, and silane are needed to enhance the aspect ratio and to reduce parasitic deposition beside the nanorods on the sapphire surface. The results reveal many similarities between InN and GaN nanorod growth showing that the process despite the large difference in growth temperature is similar. Transmission electron microscopy, spatially resolved energy dispersive X ray spectroscopy, X ray diffraction, X ray photoelectron spectroscopy, and Raman spectroscopy have been performed to analyze the structural properties. Spatially resolved cathodoluminescence investigations are carried out to verify the optical activity of the InN nanorods. The InN nanorods are expected to be the material of choice for high efficiency hot carrier solar cell