Re: why is a laser beam more powerful than a beam of natural light?

Greetings Amanda:

Scientists have power meters that measure the power of light sources in
watts. The power output of light bulbs is exactly the same as the power
output of lasers. For example a 100 watt light bulb and a 100 watt laser
would both have the same total amount light power.
So what is the difference if bulbs and lasers can put out the same amount of
power?

First; light bulbs put out light with the power distributed in all of the
colors of the rainbow and with most of the power in invisible infrared (heat)
wavelengths. This is why light bulbs get to hot to touch.
Lasers develop their power efficiently in a single wavelength of light.
The wavelength could be red, green, blue or any other color of the rainbow depending on
the type of laser used.

Second; The waves of light comming out of a light bulb are all mixed up and
no two waves are exactly the same, the peaks and the valleys of the waves are
all jumbled. Scientists call this INCOHERENT LIGHT. Lasers put out light waves
that are all of the exact same wavelength and color and all of
the waves peaks and valleys are exactly in step with each other like a marching band.
Scientists call thisCOHERENT LIGHT.

Third; Coherent light can be concentrated with mirrors and lenses into beams thousands of times
more narrow than beams of incoherent light. If you shine a flashlight
of incoherent light across a room you can measure how much the beam
spreads. The light spot will be several feet wide. If you shine a pointer laser,
across a room the beam will only be about the size of a
pencil eraser on the wall. This is the secret
of the power of laser light. One hundred watts of power from a light bulb
spread on a wall will hardly heat the wall at all. One hundred watts of laser
light in a tiny beam will burn a hole in the wall just like sunlight focussed
to a spot with a magnifying glass will burn wood. Its the ability to focus and direct
COHERENT laser light into tight beams that is the answer to your question.

In 1969 when the first astronauts were on the moon, my laboratory was
conducting an experiment for NASA in which we directed a 5 watt
argon-ion laser (a green wavelength laser now used for eye surgery) toward
the moon through a 36 inch (1 meter) diameter telescope mirror on Table
Mountain, California. The laser light spot on the moon was only one mile (1.6 km) wide.
When looking back at earth from the moon through a TV camera on the moon,
the green laser beam was a bright green light comming from the earth
and it was the only man made light on earth that could be seen from that
that great distance!

Best Regards, Your Mad Scientist
Adrian Popa