A comprehensive resource for safe and responsible laser use
Researchers at Stanford University wanted to get data on how much lift a bird generates. To monitor the wing wake and vortices, they used a laser beam spread by a lens into a plane of light. The light source was a Litron brand double-pumped Neodymium-doped yttrium lithium fluoride (Nd:YLF) laser. The light was green at 527 nanometers, and had a pulse repetition rate of 1 kHz.
A non-toxic mist in the air illuminated the light sheet, just like theatrical fog used at concert laser light shows. As the bird flew through the light, the mist scattered and showed the air patterns, in a technique called “particle imaging velocimetry” or PIV.
Bird-sized goggles were used to prevent any harm to the bird’s eyesight. The lenses came from human laser safety glasses and had an optical density of 6, meaning that they transmitted only 0.0001% of the laser light. The frame was 3D printed and was held on by veterinary tape. The goggles weighed 1.68 grams, which is roughly 6% of the bird’s body weight (equivalent to 9 pound glasses on a 150 lb. human).
Before beginning the series of experiments, the researchers trained four parrotlets “through many small stress-free steps of habituation.” After “several months of effort” with the birds, only one — a parrotlet named “Obi” — voluntarily flew with the laser goggles. According to the researchers, “[a]ll training and experimental procedures were approved by Stanford's Administrative Panel on Laboratory Animal Care.”
Twelve cameras were used. Four high-speed stereo cameras were for PIV particle motion recording and recorded 4000 frames per flight. Eight cameras were for recording Obi’s wing and head kinematics as it flew from one perch, through the laser light plane, to a landing perch.
The results give “the clearest picture to date of the wake left by a flying animal.” Unexpectedly, the wing tip vortices did not stay stable as happens with aircraft, but instead broke up quickly and violently. This had not been predicted by any previous models.
From a Stanford University news story, picked up by numerous websites and news outlets including Popular Mechanics, NBC News, The Verge, Optics.org and many others. The results were published December 6 2016 in the journal Bioinspiration & Biometrics, volume 12, number 1. Thanks to Drs. Ronald K.A.M. Mallant, MSc. for pointing out an error in our description of OD 6 density; the error has been corrected.
The laser is full color (red, green and blue combined) and is said to be harmless. The system was developed primarily as a vision aid for persons with visual defects. According to the news story, the image does not require focusing and is projected through the eye’s lens directly onto the retina.
The story notes that “the basic idea of projecting imagery onto a retina via laser has been around for decades, but miniaturizing the optics to realize a wearable form factor had been difficult until recently.”
A Fujitsu spinoff called QD Laser helped develop the glasses. They expect to begin selling them in March 2016 in Japan, Europe and the U.S. for about USD $2,000.
From PC World
TASC is working on countermeasures such as laser eye protection and the development of procedures for injury assessment. The work is being performed under the Optical Radiation Bioeffects and Safety contract with the Air Force’s 711th Human Performance Wing’s Optical Radiation Bioeffects Branch at Fort Sam Houston in San Antonio, Texas.
From the San Antonio Business Journal
Laser protection team leader Andy Mott was quoted as saying “Lasers of varying pulse width and wavelength are being developed every day. We protect against the known threats, and unknown ones. We develop protection for electronic sensors of the future, as well as the sighting systems of today.”
More details are at the Military.com story
The LaseReflect Aviator LRG10 glasses are said to mitigate the effects of laser illumination incidents. They reflect more than 99% of 532 nanometer green laser light, the most common color in laser attacks. (According to FAA statistics, about 95% of reported incidents in recent years have involved green light.) They also reflect near-infrared light at 1064 nm, which often is a byproduct of green lasers that are not manufactured with adequate IR-blocking filters. The cost is USD $299.
Custom LaseReflect Aviator glasses are available for specific colors and powers, including multiple wavelengths in a single pair of glasses. For example, blue (405 nm and 445 nm) and red (650 nm) light can also be reflected by the glasses.
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According to a professor at Embry-Riddle Aeronautical University, gold-tinted eyewear has been used by military pilots for laser protection but only works against certain wavelengths of laser light. However, said Dan Macchiarella, if Thomas’ idea “could be applied to lasers of all strengths and wavelengths, that would certainly be a big advancement.”
A March 10 2013 Orlando Sentinel story noted that funding cuts and competition for grants mean that Thomas’ research faces “some serious hurdles” to develop this idea further. Thomas said finding research money is “going to be very difficult, very difficult.”
From the Orlando Sentinel
It is not clear whether the filter is available at this time (May 2012). The company intends to incorporate it into glasses and night-vision goggles worn by pilots, to protect against flash blindness, meaning power densities from 100 µW/cm² up to 1000 µW/cm².
[NOTE: The amounts above represent about $2,400 per pair of laser protection spectacles. More information about anti-laser glasses for pilots, including non-military versions protecting against one or two visible wavelengths for roughly $100-200, is here.]
From a Teledyne Technologies press release
The eyewear, made by NoiR, significantly reduces laser light, without adversely affecting pilot vision of cockpit instruments or airport lights. Because some laser light is transmitted, pilots and flight officers will still be able to track the source of a laser illumination.
The decision to purchase the glasses was made because of recent laser incidents in the St. Louis area. A spokesperson said the eyewear is “another tool to keep us in the air.”