This sounds like a crazy question because it is. Laser pointers are intentionally designed to be safe for everyday use. It’s common knowledge that staring at a laser can be dangerous. But the question of how many laser pointers it would take to strike a fatal blow is inevitably laser pen 3000mw green rooted in the question of how powerful any given laser pointer is.

A Quick Primer on Lasers

Before we dig into the grisly mystery of how to kill a human with a laser point (or a lot of them) let’s revisit a question from high school physics: What is a laser?

The word laser is actually an acronym for “light amplification by stimulated emission of radiation.” In plain English, a laser is a single beam of light, a bunch of photons moving in the same direction. (Normally, light sprays out in all directions) High-powered lasers deposit large amounts of energy on a focused point producing heat and, in extreme cases, vicious burns. The United States Navy, for instance, has a laser that’s powerful enough to blast a drone right out laser pointer pen of the sky.

How Many Laser Pointers Would It Take to Kill a Human?

The strength of any laser—and therefore danger—is determined by the amount of power it outputs, typically measured in milliwatts. In the U.S., the Food and Drug Administration (FDA) requires all products to be 5 milliwatts or less, and some cheap laser pointers have an output power of less than 1 milliwatt. However, you can also Google “cheap laser pointer” and find a 5-milliwatt device for less than $2. Since these laser pointers originate from far off foreign lands, they’re often missing the safety hazard stickers required by the FDA. Sometimes, they’re even missing a critical shield to protect dangerous infrared light from escaping the pointer.

The dangers of infrared light alone are hardly deadly at that level, though. Infrared light is most perilous because it’s invisible so your eye’s blink reflex won’t kick in before your retina starts to burn. Even still, the burn would damage your vision, but it wouldn’t kill you. You’d need a laser much more powerful than 5 milliwatts to do that.

Or would you?

Now Let’s Get Down to Business

The crazy thing about lasers is that you can focus the beams of several low-powered lasers and create a single high-powered beam. This is no easy task, however. Multiple laser pointer beams would need to be perfectly focused by a lens that would send the combined energy in the direction of the target. It’s sort of like the “Don’t cross the beams” trick from Ghostbusters but much more scientific.

If—as our morbid goal requires—you wanted to kill a human, it would be easiest to shoot them right in the eye. A powerful enough laser could cut through the retina and burn through the person’s brain tissue. However, it would take a while, and you’d have to focus the laser on a specific point. So basically, you’d have to strap the person down or immobilize them in some fashion.

This grisly scene is hardly the death ray sort of solution you see in cartoons. The time factor is especially tricky given the simple physics of the situation. James Kakalios, a physics professor at the University of Minnesota and the author of The Physics of Superheroes, says that building a death ray out of lasers—and even a death ray in general—is pretty darn tough.

“In order to blast a hole in something, you have to deposit more energy in a short amount of time faster than the energy can be dissipated away,” Kakalios explains. “If you can do this, then you can overwhelm the bonds holding the material together, and the atoms will fly away. But if the excess energy from the lasers can be carried away as heat, then all you’ll have done is warm up the material.”

But what happens when you warm up brain matter? It melts. Considering the fact that we’re talking about cobbling together a high-powered laser out of several laser pointers, it would still probably take a decent amount of time to burn through someone’s brain.

How Many Laser Pointers Would It Take to Kill a Human?

Blasting brains with lasers is a burgeoning technique in the field of neuroscience. In small doses, beams of laser light can actually trigger brain activity and even cure pain. Tim Spellman, a postdoctoral fellow in neuroscience at Columbia, spends his days shooting lasers at mouse brains for the sake of medical research. However, he’s also acutely aware that the sustained presence of high-powered lasers could do significant damage to the brain.

“Basically you’re going to have to heat the tissue enough to combust fat, since the brain is mostly fat—that’s anywhere from 300 to 500 degrees,” Spellman said in an ema

Jim Aluminum Wireless Presenter

The Laser

This is red LED laser with a wavelength of of about 640 to 660 nanometers. It's a Class 2 laser emitting less than 1 milliwatt. The definition of Class 2 is: "Class 2 lasers emit radiation in the visible portion of the spectrum, and protection is normally afforded by the normal human aversion response (blink reflex) to bright radiant sources. They may be hazardous if viewed directly for extended periods of time. Example: laser pointers laser pointer sale."

The divergence of the beam is what one would expect from a device this inexpensive. That is, suitable for presentations up to about 10 meters. But it's not perfect. See the photo below.

Distance: 9.1 meters. Marks are 2.5 cm (1 inch) apart.

Slide Navigation

There are just two buttons on the side for forward and backward slide navigation. The range is the standard Bluetooth distance of 10 meters (33 feet). Compatibility is with iPhones back to 3GS, all iPads, MacBooks and all other Apple Bluetooth-enabled products and PCs.

Physical Characteristics

Available in Space Gray, Silver or Gold on one half. Black on the other.

Weight: 58.3 grams (2.05 ounces)

Length: 13.5 cm (5.3 inches)

MicroUSB port for charging.

The black portion (front) is nicely grippy. The rear is smooth aluminum, but still affords a good grip. There is laser pointer light match no auto-time-out, so one must turn it off when done using.

Battery

The battery is Lithium-Ion with a 600 mAh capacity. Jim says the battery life depends, of course on use. (I haven't had time to test it to depletion.) The standby time is stated as 6 months, and the battery itself is rated for 1,000 charge cycles.

The small pamphlet that accompanies is vague about the LED charge indicator light, and I had to ask. When connected to a USB charging source, the sense of the lights is the opposite of what one would think. A steady blue means "charging". A steady red means "Charging complete – device can be disconnected." That can be confusing when first connected, out of the box.

The input is 5V, DC.

Peripherals

A black, soft cloth zippered bag is included, and there's just enough room to fit the 20 cm (8 inch) charging cable (included) inside and zip it all up.

Warranty, Manual and Packaging

The warranty is one year. The outside of the box explains the features, compatibility, the battery type, connectivity, warranty and includes Jim phone number and email. The small, eight panel User Manual (pamphlet) explains the controls fairly well (except for the sense of the charging light) and how to Bluetooth pair it with Windows (7,8,8.1, and 10) PCs, Macs (OS X 10.4 or later), or iOS 5 or later devices. It's compatible with Microsoft PowerPoint and Apple's Keynote on an iPad or iPhone.

Detail of buttons. Shown in Space Gray and black

Observations

I had a class to teach last weekend and used this product with my iPad Pro and Apple's Keynote. It paired with my iPad immediately the day before and stayed paired in the next day's presentation with no hassle.

No doubt the diameter is dictated by the internal electronics and battery, but I found its size, grip and heft pleasant, However, the flush buttons on the side won't keep it from rolling on a desk. That said, one side seems more weighted than the other, and it naturally resists rolling. A blue LED near the front alerts the user that the beam is on, just in case.

All in all, I liked this device a lot. It's simple and easy to use, well built, good looking and nicely priced. If you do a lot of presentations, it's well worth the money.