A comprehensive resource for safe and responsible laser use
The July 1 2018 report appeared the In South China Morning Post. It quoted a “researcher who had [taken] part in the development and field testing of a prototype at the Xian Institute of Optics and Precision Mechanics at the Chinese Academy of Sciences in Shaanxi province. The source said “The pain will be beyond endurance.” Another researcher said that because the beam is invisible and noiseless, “nobody will know where the attack came from. It will look like an accident.”
A technical document stressed the “non-lethal” nature of the laser rifle, listing attacks such as burning the banners or clothing of “illegal protests”.
The laser capability claims were disputed, however, by numerous news outlets.
TechCrunch writer Devin Coldewey first noted that military laser systems capable of delivering damaging heat over hundreds of meters require “on the order of tens of kilowatts, and those have trouble causing serious damage.” He calculated that a Tesla Powerwall using lithium ion batteries produces a few kilowatts of power and weighs over 200 pounds. (The complete laser rifle weighs 6.6 pounds.) Coldewey said the problem was atmospheric attenuation of the laser beam which is “non-trivial at anything beyond, say, a few dozen meters. By the time you get out to 800 [meters, the laser’s claimed range] the air and water the beam has traveled through [are] enough to reduce it [to] a fraction of its original power.”
They noted that the technique could be scaled up to create laser-powered drones that could do useful work: “commercial laser-powered flight applications are only a few years away.”
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The device came to public attention September 28 2013 when gadget blog Gizmodo published an article entitled Holy Crap, This Real-Life Laser Rifle Cuts Through Metal Like Nothing. The article links to TWI’s YouTube video of the laser in action.
For the military laser enthusiast, the catalog contains a number of other laser devices such as the AN/PEQ-14 Integrated Laser White Light Pointer (actually a white flashlight plus a visible and an invisible laser):
From the Program Executive Officer Soldier Portfolio FY2012 catalog. The LA-8/P is on printed pages 138-139, electronic pages 146-147. Originally found via GovWin.
Commentary from LaserPointerSafety.com: Although the LA-8/P Aircrew Laser Pointer does not emit a visible beam, it would be easy to make a visible version so that aircrews could “fire back” at persons on the ground aiming laser pointers at them. Whether this is a wise idea is another matter.
The NIST team came up with a simple “home test” so that interested persons can test their own laser pointers. The test requires a digital or cellphone camera, a compact disc used to spread out the wavelengths, a webcam to view infrared light, and an infrared TV remote control.
At top, light from a green laser pointer is diffracted (spread out) by a compact disc and viewed with a digital camera that can see only visible light. At bottom, a webcam with no infrared-blocking filter shows this laser also emits infrared laser light (white dots). For this unit, the invisible infrared light is more powerful than the visible green light. (NIST photo)
The unwanted and potentially hazardous infrared light is due to misaligned or missing filters in laser pointers that use infrared to generate visible green light. Low-cost pointers are at special risk, due to cutting corners in design, materials or manufacture to reduce costs.
The team warns that, whether or not a laser pointer emits dangerous levels of infrared, users should “never point the lasers at the eyes or aim them at surfaces such as windows which can reflect infrared light [as well as visible light] back to the user” or others in the area.
For more information:
- NIST press release summarizing the issue
- NIST technical note A Green Laser Pointer Hazard which includes instructions on how to test to see if a green laser pointer has unwanted or excess infrared light emission (PDF format)
UPDATE - March 2011: A laser expert has privately warned LaserPointerSafety.com that the CD technique requires caution. This is because when the laser light is diffracted, the infrared light is no longer co-linear (same path) as the visible light. Therefore, the viewer cannot know exactly where the IR light is going unless they are looking through an IR-sensitive camera or webcam.