Laser pointer label compliance is a newly quantified safety issue affecting the UW campus. This project will develop a simple test to evaluate the validity of a laser pointer radiation class label.
Develop and evaluate simple test stands for comparing an uncertified laser pointer to a standard and for absolute measurements. Evaluate filters to bring existing laser pointers into compliance.
Test stand options:
Option 1) Optical power meter test stand similar to NIST's (meter borrowed from instructional labs)
Option 2) At-home test for consumers based on iPhone and other mobile device cameras. Shine laser on some standard readily available specular reflector (Kleenex?) and image along with some standard light source (LED, iPhone white screen?) with mobile camera.
Option 1) Commercial scientific grade neutral density filter insert
Option 2) Consumer grade filter add-on recommendations, eg. transparent tape.
National Institute of Standards and Technology (NIST) researchers have tested 122 laser pointers and found that nearly 90% of green pointers and about 44% of red pointers tested were out of compliance with federal safety regulations.
The published article is freely available online (http://iopscience.iop.org/0957-0233/24/4/045202/ ) and suggests that most common commercial green and red laser pointers can damage the retina if momentarily flashed (<0.25s) across the eye. UW presenters routinely use laser pointers which likely carry a (only marginally safe) 3R class label and which actually are hazardous 3B class devices.
Green: "The power output from 11 of the 12 devices exceeded the Class 3R limit at one or more wavelengths, and as such, they operated as de facto Class 3B devices" Red: "the power output from 6 of the 11 devices exceeded the Class 3R limit and, as such, they operated as de facto Class 3B devices,"
"More powerful Class 3B and/or Class 4 lasers are capable of inducing injury from even momentary exposure (<0.25 s) [8, 9]. In fact, the American Standard for the Safe Use of Lasers (ANSI Z136.1-2007) dictates the use of protective eyewear, designated laser control areas, laser hazard signage, and laser safety training for all Class 3B and Class 4 lasers, thereby prohibiting the use of these products for demonstration purposes by untrained users [8, 11]. "
I have posted this new project to Physics Garage on laser pointer safety. Brett and I would love your help with it. It responds to a newly quantified safety issue associated with laser pointers affecting our community and you could help from home over break. Take a look at
and read the original article and cited literature.
Someone(s) could search PubMed for information on laser pointer eye injury statistics nationally and in Madison and at UW, and find some summary of the literature that has led to the laser safety classification system. Please post this information to the project page in the form of a powerpoint or pdf of a powerpoint. The goal here to provide a sense of the hazard posed by mislabeled laser pointers on campus. Precisely what power levels and energy levels lead to what retinal damage and what is recoverable and what is not recoverable? How does this depend upon the size and angle and wavelength of the beam?
If you are in town and want to start tests, note that laser pointers and lasers of any kind are proscribed from us in the Garage without approval of procedures at a minimum and possibly of supervision, for precisely the reason this project seeks to better understand. Talk to Brett of Duncan.
It would be great if someone could look into (use Web of Science and Google Scholar) the device-to-device and image-to-image reproducibility of mobile device camera illuminance metering. If my iPhone/Android thinks a laser is too bright now, will it do so tomorrow and will yours think so? And think about possible consumer grade standard light sources that consumers might use to compare to their laser pointer. How good a standard can you come up with? How close in frequency is it to the common red and green lasers and how much error is there in comparing the laser to the standard? We are shooting for something like 10%.
If you get started on this, be sure to add your name to the project page and check back now and again to share information. Also email Duncan and Brett.
Basic info: www.fit.edu/safety/documents/Laser%20Safety.pdf
Florida Institute of Technology University Policy and Procedure, Laser Use and Safety Policy
FDA Tips for Consumers: http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm166649.htm#TipsforConsumers
Laser pointer safety: http://www.laserpointersafety.com/treatment/treatment.html
IR laser damage studies: http://techdigest.jhuapl.edu/TD/td2601/McCally.pdf