AbstractAn Italian university research group from Rome has developed in collaboration with an R&D institute a device for detecting topographical features of an almost flat surface of several square centimetres using a modified shear-force microscope. A prototype has already been tested successfully. The instrument can be used for several applications in the fields of cultural heritage, microelectronics, micromachining, etc. The research group is looking for a technical and commercial agreement.
DetailsGetting the 3D topographic image of a surface is very important for:
- The measuring of surface roughness.
- The recognition of the form of traces left by tools used in manufacture of the surface.
- To highlight figures and shapes that are not recognisable with the naked eye.
The instrument necessary to get a topographic image of a surface is called profilometer. A profilometer is a measuring instrument for surface profiles, in order to quantify a surface’s roughness. The vertical resolution is usually in the nanometre level, though lateral resolution is usually poorer.
Microscopic topographic measures are performed by very fine instruments such as Scanning Tunnelling (STM) Microscopes or Atomic Force Microscopes (AFM).
Large surfaces measures are preformed by contact profilometer (a device similar to a phonograph, which measures a surface as the surface is moved relative to the contact profilometer's stylus) or optical profilometer (that is a non-contact method for providing much of the same information as a stylus-based profilometer).
An Italian university research group from Rome has developed a profilometer for large surfaces by modifying a shear-force microscope.
This instrument is composed of three DC precision motors that move the sample holder: two of them perform the surface scanning, and the third one performs the vertical motion. The latter is stopped when the sensor tip experiences a sufficiently high shear force before touching the sample surface. The horizontal scanning is controlled by software either for scanning a microscopic surface with very high resolution or for scanning wide surfaces.
A prototype has been tested successfully. During the test the research group has observed images of a few square millimetres, the height whereof was 2 mm from the surface of the object scanner.
1) The instrument use the atomic shear-force sensitivity to bring the point of the instrument to the surface.
2) The instrument does not touch the surface like optical profilometers do.
3) For microscopic surfaces (um2) the sensitivity of this instrument is less than 0.1 micron for vertical and horizontal resolution.
4) For large surfaces (mm2 or cm2) the vertical resolution is in the micron level.
The instrument offered here is very useful in the field of cultural heritage, where it’s very important that every analysis of the object is done without destructive techniques.
With respect to other topographical instruments, the device proposed has the advantage of i) scanning a wide area; ii) no contact between the surface and the device tip, iii) excellent vertical resolution; iv) very good lateral resolution.