In repsonse to Dr. Linn's question about computer monitors for use
on NMR spectrometers, we have found that there are three practical
solutions to the stray field problem:
1. Buy a conventional monitor (like the ViewSonic) and enclose it
in a box made from soft iron, mu metal, or similar ferromagnetic material
with high permeability. The box encloses the monitor on five sides and is
large enough so that the monitor is recessed by a few inches from the front
of the box. The box must also be large enough to permit good ventilation.
2. Buy a monitor with good internal shielding. We have found that
EIZO/NANAO monitors work very well in a moderate stray field of about 2
gauss without any additional shielding. The orientation of the monitor
relative to the field is important, and there will be some orientations for
which the distortion becomes much worse.
3. Buy a active matrix LCD display, which is totally impervious to
stray field distortions. These are now available in sizes up to 20" from
NEC, but are rather expensive. This is the solution to pick if a monitor
must be located in a field greater than about 10 gauss, where conventional
shielding is ineffective.
Regards,
Ken Fishbein
Facility Manager,
NMR Unit
NIH/NIA/GRC
Ph. (410) 558-8512
FAX (410) 558-8323 or 8173
E-mail: fishbein@vax.grc.nia.nih.gov
Address: Ken Fishbein
NIH/NIA/GRC
5600 Nathan Shock Drive
Baltimore, MD 21224 USA