Andrew Grebneff wrote:

> Is there anyone out there who knows about, or knows someone who does,
> synthetic-aperture radar?
>
> Synthetic-aperture radar on aircraft or satellites takes some beautiful B&W
> photos of the earth's surface. I am wondering if it can be downscaled
> somewhat for use as an SEM replacement. Just think, no huge maintenance
> costs and no irremovable gold coating of specimens!

Hello!

Hi Andrew,

In order to scale down a radar, that is to the resolution of SEM, you would
have to
reduce the wavelength to that used by the SEM. So, for all practical purposes
the
SEM is a radar of sorts. One of the reasons the spaceborne radars are so useful

is that they see thru cloud cover (well some of them better than others) and
they
actually resolve distance, again depending, on the wavelength. The distance
resolution
gives a very neat 3-D image of the area being scanned.

Some of the radars I have worked with are at 95 GHz  (millimeter wave radar)
so the resolution is millimeters. They are not too good at penetrating cloud
cover, rain,
etc. Too much absorption of the energy. To do what a SEM does you would have to

scale down to x-rays at about 0.05 to 150 angstroms (1 A = 10 to the -8
centimeters).
The gold coating or some such would still have to be used.

Later,

Emilio Jorge Power

Please visit;
"The Liguus Home Page"
http://www.geocities.com/Eureka/Gold/9440/liguus/lighompa.html
West Melbourne, Florida  USA