H.-J. Büchner

Standing-wave interferometer

An interferometric position sensor was developed using the concept of sampling a standing wave. Interference of a standing wave created in front of a plane mirror can be detected by thin, partly transparent sensors based on amorphous silicon. The optical thickness of the absorption layer is thinner than the wavelength λ of the incident light. Detection of minima and maxima of the standing wave can be used to determine the relative displacement of the plane mirror and the detector. For determination of bidirectional fringe counting, two detectors with a certain phase shift were introduced into the standing wave. An integrated solution of two stacked n-i-p diodes and a phase shifter will be presented. The operation principle of the device will be demonstrated by measured Lissajous figures.

Standing wave detection by thin transparent n-i-p diodes of amorphous silicon

Abstract Interferences of a standing wave created in front of a plane mirror can be detected by thin transparent sensors based on a n–i–p layer sequence with an optical thickness of the i-layer thinner than the wavelength λ of the incident light. The detection of the minima and maxima of a standing wave can be used to determine the relative displacement of the plane mirror towards the detector. The optoelectronic properties of thin transparent detectors are studied regarding reflection and transmission, capacitance, and ability to distinguish between the minima and maxima of the standing wave. The developed sensors with a high transmittance consist of thin diodes of amorphous silicon (a-Si:H) and/or silicon carbide (a-SiC:H) with an optical thickness of λ/2 embedded between two transparent conductive oxide layers with an optical thickness of 3λ/4. The highest yield and the best device performance are achieved for detectors with an absorber layer of a-SiC:H.

The Metrological Basis and Operation of Nanopositioning and Nanomeasuring Machine NMM-1Metrologische Grundlagen und Wirkungsweise der Nanopositionier- und Messmaschine NMM-1

Abstract After an explanation of the set-up of a nanomeasuring machine NMM-1, its high performance is described with a metrological analysis. This analysis shows some of today´s limits of nanopositioning and nanomeasuring engineering. Single, double and triple beam plane mirror interferometers are applied in the nanomeasuring machine in order to measure and control the six degrees of freedom of the 3D nanopositioning stage. The various applications of the nanomeasuring machine are based on the installation of optical and tactile nanoprobes above the 3D nanopositioning stage. The set-up, function and measurement results of some zero-point nanoprobes in combination with the nanomeasuring machine are explained.

Nanometrology – Nanopositioning- and Nanomeasuring Machine with Integrated Nanopobes

The paper describes the operation of a high-precision wide scale three-dimensional nanopositioning and nanomeasuring machine (NPM-Machine) having a resolution of 0,1 nm over the positioning and measuring range of 25 mm x 25 mm x 5 mm. The NPM-Machine has been developed by the Technische Universität Ilmenau and manufactured by the SIOS Meßtechnik GmbH Ilmenau. The machines are operating successfully in several German and foreign research institutes including the Physikalisch-Technische Bundesanstalt (PTB). The integration of several, optical and tactile probe systems and scanning force microscopes makes the NPM-Machine suitable for various tasks, such as large-area scanning probe microscopy, mask and water inspection, circuit testing as well as measuring optical and mechanical precision work pieces such as micro lens arrays, concave lenses, mm-step height standards.

Standing-wave interferometer based on partially transparent photodiodes

A novel interferometer concept will be presented which is based on an optical standing wave. This standing wave is scanned by a novel, partially transparent photodetector, which is designed as nip-photodiode and contacted with transparent conductive oxide (TCO). Two transparent photodiodes are integrated to a transparent phase-sensitive sensor. The photodiodes are longitudinally arranged on the optical axis of the standing wave and generate a sine and a cosine signal for the up- and down-counting of the intensity maxima and minima of the standing wave. The layer thickness of the transparent photodiodes has been designed so as to take appropriate coating into account. These measures are demonstrated by a number of experimental results. An incorrect phase relation between the photodiodes will be corrected using the Heydemann algorithm. The non-linearity of the interferometer at a length of

Interferometric detection of adhesion-induced nano-deflections

A novel micro-tribology tester comprising a highly sensitive force-detecting cantilever and a single-beam interferometer is introduced. To avoid any disturbance of the highly sensitive mechanical set-up the front side of the cantilever was polished to create the necessary reflector. The interferometer utilizes an aperture through which the interferogram is evaluated. In contrast to an atomic force microscope, where only a sharp tip interacts with the surface, two planes can be brought into contact. To measure adhesion one of the two samples is attached to a piezo-stack, performing an oscillatory motion towards and away from the second sample. Since the second sample is attached to the cantilever, any displacement can be detected by the interferometer. With a cantilever spring constant of and an interferometer length resolution of 1 nm, forces down to 5 nN can be resolved.

Design aspects in the development of a standing wave interferometer

A novel interferometer based on sampling the maxima and minima of intensity of an optical standing wave has been developed. The photoelectric detection of the standing wave is performed by using a partially transparent thin-film photodiode. The automatic bidirectional fringe counting is provided by a partially transparent and phase-sensitive detector which is realized by the integration of two stacked transparent photodiodes along the optical axis of the standing wave. To obtain the ideal sine and cosine signals, the transparent phase-sensitive detector has to be optimized by adjusting the thickness of the single layers. Some features of optimization will be presented and explained. Length measurements have been demonstrated by displacing the plane mirror and bidirectional fringe counting within the standing wave.

Détection interférométrique de déflections nanoscopiques induites par adhésion

A novel micro-tribology tester comprising a highly sensitive force-detecting cantilever and a single-beam interferometer is introduced. To avoid any disturbance of the highly sensitive mechanical set-up the front side of the cantilever was polished to create the necessary reflector. The interferometer utilizes an aperture through which the interferogram is evaluated. In contrast to an atomic force microscope, where only a sharp tip interacts with the surface, two planes can be brought into contact. To measure adhesion one of the two samples is attached to a piezo-stack, performing an oscillatory motion towards and away from the second sample. Since the second sample is attached to the cantilever, any displacement can be detected by the interferometer. With a cantilever spring constant of and an interferometer length resolution of 1 nm, forces down to 5 nN can be resolved.

Interferometric detection of adhesion-induced nano-deflections Détection interférométrique de déflections nanoscopiques induites par adhésion

A novel micro-tribology tester comprising a highly sensitive force-detecting cantilever and a single-beam interferometer is introduced. To avoid any disturbance of the highly sensitive mechanical set-up the front side of the cantilever was polished to create the necessary reflector. The interferometer utilizes an aperture through which the interferogram is evaluated. In contrast to an atomic force microscope, where only a sharp tip interacts with the surface, two planes can be brought into contact. To measure adhesion one of the two samples is attached to a piezo-stack, performing an oscillatory motion towards and away from the second sample. Since the second sample is attached to the cantilever, any displacement can be detected by the interferometer. With a cantilever spring constant of and an interferometer length resolution of 1 nm, forces down to 5 nN can be resolved.