Thanks to all for the information. I guess I should have included the reason I asked the original question about light meters.
Remember back in the 90’s when lawsuits about carpal tunnel due to keyboards were all the rage. It seems that eye damage is becoming the new carpal tunnel. Employers and manufacturers are starting to get sued by employees claiming eye damage caused by something they are exposed to on the job. Employees can claim all kinds of different eye damage such as spots, blurriness, sensitivity, headaches, etc. which is very difficult to prove otherwise. It appears to be easy money for the plaintiff as well as lawyers. Employers are looking for a simple method of measuring a worker’s area and documenting the light energy to cover them in case of a law suit. Manufacturers are looking to stay out of such lawsuits as well. There are specs for Lasers and LEDs, but there are many other light sources on products that are not covered. Back light displays, filaments, and heating elements for example. And the combination with ambient lighting also comes into play. Is there any established method to measure the light energy of a product or employee work area as related to the operator or employee? I’m thinking something like a thermal imaging camera that would instead of displaying heat in different colors but instead would display different light levels in different colors. The colors would relate to some light energy value. As I look around my little cubical, I can see two low wattage florescent lights, my computer monitor, and LEDs on my computer speakers and computer. No big deal. But, if I look straight up, about 30 feet in the air over my cube there are some 400 watt light fixtures. I assume if I stared at one of these lights for 8 hours a day I would be blind in about a week. However, my mom taught me never to look directly at a light bulb so not to fear. But, if I became a disgruntled ex-employee I’m sure I could find a lawyer who would take the case. As I am approaching 50 years of age, my eyesight is not what it once was so maybe something at work is to blame for it (wink, wink). I think you get my point. Do organizations, such as OSHA, have a method to measure light (and sound) on location when they do inspections or is it just a guess by observation? The Other Brian ________________________________ From: Barry Rowland [mailto:[email protected]] Sent: Saturday, October 18, 2008 11:13 PM To: Kunde, Brian; Pete Perkins Subject: Re: Light Meter Recommondations - LEDs hi guys ... there's no simple answer here, as the exposure criteria are strongly dependent on wavelength, and are modified by the emitting aperture and optics. a photometric measurement device will not give the appropriate response, as it is weighted by eye daytime vision sensitivity, rather than the damage sensitivity functions... CIE has a couple of Technical Committees dealing with the appropriate measurement techniques from a standards view. Presently, you need to use a spectroradiometer and some kind of adaptive optics to get useful results... as i recall, part of the problem with the measurements is the wide range of sensitivity across the spectrum of interest. Brian, you may be able to come up with something simplified if you have constrained LED emitter wavelengths, known apertures/optics, and need a "no need to test further" or "maybe this needs a deeper look" answer .... right now, it looks as though you need not be worried about much until you get into >1 watt, and focusing optics . best regards, barry rowland salo finland On 17-Oct-08, at 2:03 AM, Pete Perkins wrote: Brian, The changing technology is being dealt with in several ways. IEC 60825-2 has been developed as safety requirements for LEDs that are not lasers. At the 2005 IEEE PSES meeting an interesting paper was given. Light Emitting Diode Safety and Safety Standards by Altkorn, Milkovich and Rider was given. From the Abstract: Concerns about the safety of light emitted by LEDs are being raised as LED power output, wavelength coverage, and low-cost availability grow. Potential safety issues include ocular tissue damage and glare. Research, standard, and guidelines covering these and related issues are reviewed. The article includes a bibliography of 18 cited references. A good photometer that provides a graph of the spectral output is essential, in my opinion; it should be able to provide both broadband and eye sensitivity curves. There are reasons to be concerned about LEDs under some conditions. You should become informed as to the technical issues involved and take appropriate data on your products to support any needed actions to maintain a safe product in use. :>) br, Pete Peter E Perkins, PE Principal Product Safety Engineer PO Box 23427 Tigard, ORe 97281-3427 503/452-1201 fone/fax [email protected] From: [email protected] [mailto:[email protected]] On Behalf Of Kunde, Brian Sent: Tuesday, October 14, 2008 8:20 AM To: [email protected] Subject: Light Meter Recommondations First, I want to apologize to those who might be offended by this email and my lack of knowledge on this topic. But from time to time we hear about law suits (possible frivolous) dealing with eye damage from devices with displays and LEDs. What we would like to come up with a simple method to pre-test products with some kind of light meter and have it give us a number or graph that we can quickly determine if there is any reason to be concerned. So, 1. Am I crazy for even thinking this way? 2. Can anyone recommend such a light meter or other measuring device (make/models)? 3. Can anyone give me rough numbers, values, or a standard which defines light levels/frequency that we can use as a go/no-go value? Thanks to all for your time. The Other Brian LECO Corporation Notice: This communication may contain confidential information intended for the named recipient(s) only. If you received this by mistake, please destroy it and notify us of the error. Thank you. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc _________________________ LECO Corporation Notice: This communication may contain confidential information intended for the named recipient(s) only. If you received this by mistake, please destroy it and notify us of the error. Thank you. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
