Laser Strength and Control
Name: Alexander W
Can a Laser stron enought to cut paper, yet have a
By controlable lenght I mean that the lasers energy is limited to a certain area,
and that it will not exceed that area, yet, be strong enouth to cut paper
in any part of that area?
Is this posible to archive this without using mirrors for deflecting the
How big and coslty would it be to make such a device? Please answer, im
trying o do sucha device for my Physics proyect.
You could limit the range within which a laser beam is intense enough to cut
paper by beginning with a wide beam and focusing it with a short-focal-length
lens. The intensity in the focal spot will be much greater than it is
away from the focal spot. Such a laser would be intense enough to blind
you even well away from the focal spot. I don't know how much it would cost.
You can use a laser to cut metals. This is done routinely. Because a laser
beam's power per unit area (referred to as heat flux) can be very high, you
can use a pulsed laser to cut almost instantly by ablating the metal. The
fact the you can RAPIDLY raise the temperature of the metal to its melting
point (before heat starts to spread to other parts of the item being cut)
makes it possible to make clean and clear cuts (in many metals).
I am sure you can cut paper too but I do not know off hand what laser power
should be used. The problem I see is that the paper may catch fire. Most
metals melt or evaporate without being ignited. Paper (and a host of other
materials) are different in that once they reach a temperature (called the
ignition temperature), they catch fire. If you do this entire operation in
a CO2 environment, the fire could be self-limiting.
Lasers which have sufficient power to cut metals are rather dangerous to
work with and users must receive safety and operating courses to handle
lasers. Even small amount of laser reflected from the metal being cut can
blind a person. In any case, you may want to get a basic book on lasers
from your library and review it first.
If you prefer a safe thermal method of cutting paper, I suggest the use a
magnifying glass with sun rays (or a light source). You can actually make
a lens made of ice (which nevertheless focuses the incoming beam). You can
also use a hot wire (by applying electricity from a battery across a
suitable metal wire) to cut a piece of paper. In these cases, you need to
be aware that the paper will catch fire and thus, safety should be the
priority # 1 in the planning and conducting the demonstration. You should
discuss the project with your teacher(s) for guidance and advice before
spending time and effort on it.
Dr. Ali Khounsary
Advanced Photon Source
Argonne National Laboratory
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Update: June 2012