Navigation Links
NIST researchers measure high infrared power levels from some green lasers
Date:8/4/2010

Green laser pointers have become a popular consumer item, delivering light that's brighter to the eye than red lasers, but stories have circulated on the Web about the potential hazards of inexpensive models. Now, a team led by physicist Charles Clark at the National Institute of Standards and Technology (NIST) puts some numbers to the problem. In one case, the group found that a green laser pointer emitted almost twice its rated power level of lightbut at invisible and potentially dangerous infrared wavelengths rather than green. A new NIST technical note* describes the nature of the problem as well as a home test using an inexpensive webcam that can detect excess infrared light from green lasers.

Late last year, the research team purchased three low-cost green laser pointers advertised to have a power output of 10 milliwatts (mW). Measurements showed that one unit emitted dim green light but delivered infrared levels of nearly 20 mWpowerful enough to cause retinal damage to an individual before he or she is aware of the invisible light. NIST's Jemellie Galang and her colleagues repeated the tests with several other laser pointers and found similarly intense infrared emissions in some but not all units.

The problem stems from inadequate procedures in manufacturing quality assurance, according to the research team. Inside a green laser pointer, infrared light from a semiconductor diode laser pumps infrared light at a wavelength of 808 nm into a transparent crystal of yttrium orthovanadate doped with neodymium atoms (Nd:YVO4), causing the crystal to lase even deeper in the infrared, at 1064 nm. This light passes through a crystal of potassium titanyl phosphate (KTP), which emits light of half the wavelength: 532 nm, the familiar color of the green laser pointer.

However, if the KTP crystal is misaligned, little of the 1064 nm light is converted into green light, and most of it comes out as infrared. Excess infrared leakage can also occur if the coatings at both ends of the crystal that act as mirrors for the infrared laser light are too thin.

The NIST team says this problem could be solved by incorporating an inexpensive infrared filter at the end of the laser, which could reduce infrared emissions by 100-1000 times depending on quality and cost. Although these filters exist in modern digital cameras and more expensive green laser pointers, they often are left out of the inexpensive models.

The team demonstrates a home test that laser hobbyists could conduct to detect excessive infrared leakage, by using a common digital or cell phone camera, a compact disc, a webcam and a TV remote control. Regardless, they say owners of the devices should never point the lasers at the eyes or aim them at surfaces such as windows, which can reflect infrared light back to the usera particularly subtle hazard because many modern energy-saving windows have coatings designed specifically to reflect infrared.


'/>"/>

Contact: Ben Stein
ben.stein@nist.gov
301-975-3097
National Institute of Standards and Technology (NIST)
Source:Eurekalert  

Related medicine news :

1. Mayo Clinic researchers share latest findings in CT radiation dose reduction efforts
2. Researchers develop advanced search tool to help physicians sort and retrieve vital EMR data
3. Researchers identify key enzyme in DNA repair pathway
4. Researchers study benefits of white button mushrooms
5. Use of decision-aid program increases safety for women experiencing abuse, researchers find
6. Researchers uncover biological rationale for why intensive lupus treatment works
7. OHSU Knight Cancer Institute researchers isolate importance of gene in breast cancer prognosis
8. Researchers pinpoint key stem cells for eating and sex
9. BUSPH researchers link widely used chemicals to ADHD in children
10. Researchers Use Ecstasy to Treat PTSD
11. UC San Diego researchers find cause of metabolic disease -- and possible cure
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
NIST researchers measure high infrared power levels from some green lasers
(Date:10/13/2017)... ... October 13, 2017 , ... Many families have long-term ... long-term care insurance companies have a waiver for care if the client has a ... when the family pays for care, is often waived, so the benefits from their ...
(Date:10/13/2017)... ... October 13, 2017 , ... ... viewers the lowdown on sciatica in a new episode of "Success Files," which ... current events and innovation and investigates each subject in-depth with passion and integrity. ...
(Date:10/12/2017)... ... October 12, 2017 , ... CitiDent and San Francisco dentists, ... cutting-edge Oventus O2Vent technology. As many as 18 million Americans are estimated to ... breathing. Oral appliances can offer significant relief to about 75 percent of people ...
(Date:10/12/2017)... ... 12, 2017 , ... Asante, a nationally recognized health system ... their existing home health joint venture through an agreement, effective October 1, 2017, ... venture home health company with Asante, delivering clinically integrated care, for the past ...
(Date:10/12/2017)... ... October 12, 2017 , ... On Saturday, October 21, the ... – Miles by Moonlight to raise money for the American Heart Association Heart Walk. ... , Teams will work together to keep their treadmills moving for 5 hours. Treadmills ...
Breaking Medicine News(10 mins):
(Date:9/25/2017)... 25, 2017  EpiVax, Inc., a leader in ... immune-engineering today announced the launch of EpiVax Oncology ... personalized therapeutic cancer vaccines. EpiVax has provided $500,000 ... to enabling technologies to the new precision immunotherapy ... EpiVax Oncology as Chief Executive Officer. Gad brings ...
(Date:9/22/2017)... 2017  As the latest Obamacare repeal effort moves ... (R-LA) and Lindsey Graham (R-SC) medical ... device industry is in an odd place.  The industry ... excise tax on medical device sales passed along with ... patients, increased visits and hospital customers with the funding ...
(Date:9/19/2017)... ARBOR, Mich. , Sept. 19, 2017 HistoSonics, Inc., a venture-backed medical device ... precise destruction of targeted tissues, announced three leadership team developments today:   ... Stopek, PhD ... ... Veteran medical device executive ...
Breaking Medicine Technology: