Browse Prior Art Database

Force Measurement With High Sensitivity Application to Surface Inspection at the Angstrom Scale

IP.com Disclosure Number: IPCOM000040506D
Original Publication Date: 1987-Nov-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Martin, Y: AUTHOR [+3]

Abstract

A new technique measures forces, down to 5 x 10-16N on a sub-micron scale. A small tip, having a diameter D&100Ao, at the end of a spring is vibrated close to a solid. Linear and non linear AC contact forces between the tip and the solid are measured through the resulting tip displacement with a highly sensitive laser probe. Profiling and "contact" inspection can be done nondestructively on an Angstrom scale. In operation, a metallic spring tip is mounted on a small PZT transducer and vibrated close to the surface of the solid to be examined. A laser heterodyne probe accurately measures the AC displacement of the spring.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 80% of the total text.

Page 1 of 1

Force Measurement With High Sensitivity Application to Surface Inspection at the Angstrom Scale

A new technique measures forces, down to 5 x 10-16N on a sub-micron scale. A small tip, having a diameter D&100Ao, at the end of a spring is vibrated close to a solid. Linear and non linear AC contact forces between the tip and the solid are measured through the resulting tip displacement with a highly sensitive laser probe. Profiling and "contact" inspection can be done nondestructively on an Angstrom scale. In operation, a metallic spring tip is mounted on a small PZT transducer and vibrated close to the surface of the solid to be examined. A laser heterodyne probe accurately measures the AC displacement of the spring. When the tip is brought close to the surface, interactive forces between the tip and the surface (van der Waals forces, or electronic repulsion -contact force-) modify the AC displacement at the fundamental frequency, giving some information concerning the absorbed mechanical power, and generate harmonics of the AC vibration frequency. Both fundamental and harmonic vibrations can be measured in order to: (a) acquire surface information, and (b) control the tip- surface distance. The AC driving voltage on the PZT and the DC position of the tip over the surface are input parameters that can be controlled in order to monitor the AC and DC force of the tip on the solid. Spectroscopy of non-linear tip-surface interactions could be achieved. Interaction with...