Undeniable Friday: Laser Pointer Death-Ray

Friday, October 13, 2006

Today's video is not a good party trick. It is a warning about a danger of laser pointers which is not well known, and which has received little media attention.

Flash version

The problem lies in the difference between the deadly 1914 LASER, and its modern descendent. In order to render the device safe for civilian use, the beam had to be converted from high intensity, narrow band radiation to wider band, low intensity radiation. As light buffs know, this tradeoff can be achieved with a concave lens.

Here's the issue: the conversion can be reversed with a simple convex lens, i.e. a magnifying glass. As you can see in the video, the results are disastrous.

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Blogger CH!LL said...

omg thats so true

9:51 PM  
Blogger Jett Logic said...

Class 1 laser devices have a maximum of 1mW output and are harmeless even in the hands of Dan Serena, since your eye's close/avert reaction is fast enough to avoid damage if you look at it. Class 1M can harm the eye (before natural aversion reflex) if looked at through a magnifying glass.

Class 2-3 lasers damage the eye but not the skin (don't konw about when magnified). It takes a Class 4 laster (>500mW), to damage the skin.


8:17 AM  
Blogger Jackson said...

I WANT to believe, but here's the thing: That video looks WAAAAY doctored. Why would the doll's head EXPLODE? It was clearly an explosion, it didn't melt or burn. Then, after its head exploded the rest burned way too fast, as if it had been soaked in lighter fluid.

I'm not denying that common laser pointers might become dangerous when magnified, but I question whether this video is an accurate representation of that danger.

11:54 AM  
Blogger Kurt said...

How would a simple lens change the energy output of a harmless light source? The humor is in people believing this video.

12:18 PM  
Blogger Jorge said...

Yeah.... I'm gonna have to call shenannigans.

12:23 PM  
Blogger Ben said...

Yeah.... I might believe the premise, but slowing this baby down you can see there is an explosion. Kind of lame.

1:52 PM  
Blogger not said...

nobody said it was not soaked in lighter fluid. it was probably soaked for effect. but the premise is true. and the laser was the cause of the explosion

9:13 AM  
Blogger Gulli said...

A simple lens can convert the wavelength composition of light from narrow band to wide band? That's news to me.

A lens can widen or narrow the ray itself, but if it expands or contracts the band of wavelengths present in the light, then I must have dozed off a bit in physics lab.

4:44 AM  
Blogger packetrat said...


I love this site.

3:24 PM  
Blogger duffy said...

GOD, what it WRONG with you people?!! This is BRILLIANT!!! He put the damn magnifying glass in front of the laser pointer and then the doll's HEAD ESPLODE!!! YOW! CRIKEY! Jeeze-O-Pete! Didja hear that noise when the head went up? If this isn't an effective demonstration of the dangers of optics and lasers and magnifying glasses and all, I don't know what is. Best leave this stuff to properly trained scientists like Dan Serena.

3:55 PM  
Blogger bestonline323 said...


pointers are visible lasers with a relatively low power output which are frequently used in lecture halls and demonstrations to point at topics of interest on a presentation board. In a school setting, laser pointers have become ubiquitous, and they are very useful teaching aids. A drop in the price of laser pointers has also led to increased use among the general population. More common use of laser pointers has raised concerns about their safety, especially around the eyes.

The biggest concern with laser pointers and the eyes is temporary optical problems. These issues include flash blindness, glare, and afterimages. Flash blindness occurs whenever someone is exposed to a bright light source. While it only lasts for a few seconds, it can be extremely dangerous when someone is involved in a task which requires vision, such as driving. Afterimages can last for several days, and take the form of small spots in the vision. Glare, a reduction of visibility caused by bright light, occurs while the laser pointer is directed at the eyes.

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9:35 PM  
Blogger Edwin said...

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4:17 AM  
Blogger cudadave70 said...

I love doubters they must have never learned how to burn ants with a magnifying glass using the sun ,same difference just on a smaller scale

8:03 AM  

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