Re: laser pointers

[Gordon Miller <miller22@llnl.gov>]

Class 3b means the laser is capable of causing eye injury if the beam is
viewed directly or after a specular, mirror-like, reflections. It is an
internationally used classification.

Class 3b pointers are on the market. The suppliers are apparently
enterprises in the former Soviet Union and the Peoples Republic of China.

The ones I've heard about emit green energy at 532 nm wavelength and may
well emit ir energy at 1064 nm and have outputs in the 15 mW range. There
is no reason why a laser pointer should have an output >1 mW for most uses.
Common laser pointers in the USA run at 5 mW at 670 nm. The same spot or a
brighter spot can be projected using below 1 mW at 635 nm because the eye
responds much more to 635 nm energy than 670 nm energy. Risk of acute laser
injury is not wavelength dependent so buying 635 nm laser pointers allows
for an improvement in safety.

I have not heard of any reason why any laser pointer should run at >5 mW,
the upper end of what the eye can tolerate from a brief, eye blink long,
exposure.

Gordon Miller, CIH

----------------------

>For your information:
>
>I just read in a newspaper that laser pointers of class 3B will be
>forbidden in Austria from May onward. The procedure to establish the
>relevant ordinance takes that long.
>
>I do not know, what class 3B means and whether this is an internationally
>used classification. If it is not and there is interest in it I could find
>out during next week.
>
>Laser pointers which are available now without restriction have been  of
>concern in Austria since about a year, when they were found on the
>market.
>
>
>Thanks to Bruce Bugg for his information, though it is not directly related
>to health physics. I found it very interesting to read about non health
>physics concerns regarding something which is of health physics concern.
>
>
>Franz
>
>
>Franz Schoenhofer
>Habicherg. 31/7
>A-1160 Vienna
>Austria
>Tel.: +43-1-495 53 08
>Fax.: same number
>mobile phone: +43-664-338 0 333
>e-mail: schoenho@via.at
>
>Office:
>Hofrat Dr. Franz Sch–nhofer
>Federal Institute for Food Control and Research
>Department of Radiochemistry
>Kinderspitalg. 15
>A-1095 Vienna
>Austria
>Tel.: +43-1-40 490 27820
>e-mail: schoenhofer@baluf.via.at
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