Re: Laser deposition & Semi-tech [was: near anything boxes]

From: John Clark (
Date: Mon Mar 13 2000 - 09:16:06 MST

Robert J. Bradbury <> On March 13, 2000 Wrote:

>Spudboy100 wrote about the possibility of building nanotech via
>laser deposition [...] I don't think this is feasible. Normal light has
>wavelengths much bigger than atomic scales.

That's a problem but perhaps not an insurmountable problem because you can
make details much smaller that the wavelength of light you're using, even though
Ernst Abbe "proved" more than a 100 years ago that details smaller than half
the wavelength of the light used to illuminate a specimen could never be
resolved. The thing is, Abbe made a hidden assumption, namely that the
distance between the specimen and the source of light was large compared to
the wavelength. In 1956 J.A. O'Keefe proposed a "Scanning Near Field Microscope"
that would break the Abbe barrier. O'Keefe said that if light was emitted from a tiny
hole less than a wavelength away from the specimen then the resolution would
be limited only by the size of the hole, the wavelength of the light would be
irrelevant. In 1972 Eric Ash proved experimentally that O'Keefe was correct.
This technique may even be practical. Back in 1993 Eric Betzig of ATT used visible
light from a laser 10 nanometers above a sample to reveal details of the skeletal
scaffolding inside a cell as small as 15 nanometers. Visible light is about 500 nm.

    John K Clark

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