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:8/22/2017)... ... August 22, 2017 , ... “Wilderness Voices”: a collection ... travel. “Wilderness Voices” is the creation of published author, Martha McKown, an ordained ... was inspired as a very young child when her older sisters studied High School ...
(Date:8/22/2017)... Raleigh, North Carolina (PRWEB) , ... August 22, ... ... senior strategic advisor. Mr. Stewart is the Founder and Managing Member for t4 ... elements that have become critical to his definition of “success”: physician leadership development, ...
(Date:8/21/2017)... ... August 22, 2017 , ... PracticeMatch, a company that provides online resources ... physicians and advanced practitioners like nurse practitioners and physician assistants , ... November of this year. The online career fairs will allow job seekers to connect ...
(Date:8/21/2017)... (PRWEB) , ... August 21, 2017 , ... FCPX LUT ... Editors can quickly and easily add washed color grades to footage. A LUT ... LUT changes every pixel’s color to the corresponding color indicated by the table. This ...
(Date:8/21/2017)... ... August 21, 2017 , ... ... involvement program serving the people of Michigan. The new initiative fundraises for the ... at the very forefront of animal protection and welfare by addressing the root ...
Breaking Medicine News(10 mins):
(Date:8/1/2017)... 2017   CerSci Therapeutics , a non-opioid drug ... , has received notice from the National Institute on ... (NIH) that it has been awarded a Direct-to-Phase II ... in 2017 with an additional $1,000,000 to follow in ... application of their lead non-opioid drug candidate CT-044 to ...
(Date:7/28/2017)... Hill-Rom Holdings, Inc. ("Hill-Rom") (NYSE: HRC), today announced financial ... 2017, and updated its financial outlook for fiscal 2017. ... fiscal third quarter, Hill-Rom reported earnings of $0.09 per ... the prior-year period. These results reflect after-tax special items, ... related to the non-cash write-down of assets associated with ...
(Date:7/26/2017)... Colo. , July 26, 2017 E.I. ... Guttridge and the Bimini SharkLab to custom design the worlds ... images of sharks in their native habitat. In preparation ... Discovery Channel,s Shark Week, Dr. Guttridge approached EIMI ... take pregnancy diagnosis directly to hammerhead sharks underwater. ...
Breaking Medicine Technology: