Mr. Man-wai Chang wrote:
On 7/31/2018 8:13 PM, Paul wrote:
...
however, an unsafe power level may be collected by a
magnifying optic with larger aperture."

Looks like that baby is safe. Nothing to worry about.

There are counters with handheld laser scanner. And those handheld
scanners are NOT placed carefully to avoid customers, at least I saw
that in Hong Kong.

Did they do it deliberately? Is it a secret laser experiment? Well...


All laser experiments are secret.

Didn't you see the sign outside the laser
lab, before entering the room ?

https://www.repairfaq.org/sam/cl3barg2.gif

The lab may also have a light bulb and
sign, indicating an experiment is in progress.

My chemistry professor had an argon-ion laser.
And he had various safety features on the lab
to keep people out.

And guess what injury my professor had. His
eyeballs were fine. But, he was deaf in one
ear, from previously using a *pulse* laser.
The sound during the discharge, can slowly
damage your hearing. You're supposed to wear
ear protection, but he neglected to wear his
ear protection headset. Now he has paid the price,
in that his hearing in one ear (the ear facing the
machinery) is now almost gone. The new laser
he has to replace it, is CW (no more hearing damage).
And in a comedic moment, he still wears his
hearing protection now :-) I thought that was
pretty funny. If you only have one ear left,
I guess you'll over-protect it.

https://en.wikipedia.org/wiki/Laser

"In a continuous wave (CW) laser, the balance
of pump power against gain saturation and cavity
losses produces an equilibrium value of the
laser power inside the cavity; this equilibrium
determines the operating point of the laser.
"

And the output of that laser, would look a lot
like this.

https://upload.wikimedia.org/wikiped...rtechnik06.jpg

"This argon-ion laser emits blue-green light at 488 and 514 nm"

And babies weren't allowed in the lab.
Neither were visitors. I couldn't see inside
the lab (even though the laser was off).
I only got to see the door of the lab.

https://www.lasermet.com/images/warning_signs.jpg

More than one member of the chemistry department
had hearing loss. Some experiments involved
a capacitor bank and arc discharge (which gives
off ultrasonic sound during the discharge).
And ear protection headsets are so cheap...

Our laser lab at work, had a door on the front
that looked like a bank vault. A big metal door,
intended to scare the curious away. The cleaners
weren't even allowed inside, to mop the floors.
And my magnetic stripe badge wouldn't let me in
there either (no, I didn't test this :-) ).
So if lasers were secret, they were hiding something
in there. Something that needed a big metal door.
What could it be ??? I guess we'll never know.

No, they don't do laser work in there any more...
I know you're interested and all. The days of that
lab are now over with (not commercially viable).
Still, the lab had a nice front door, as that's
all I could ever see. The door had no window in
it either. You could not "sneak a peek". You
couldn't hold a baby up to a window or anything,
to test for laser light.

Paul