[Laser] Some comments on the revised rule 1.12

[C. Turner]

As is already known, the 2nd meeting of the ARRL Board of directors was 
held on July 16, 2010 and during that meeting, the board approved 
changes to the General Rules for ARRL Contests Above 50 MHz.

The minutes of this meeting may be seen here:  
http://www.arrl.org/files/file/About%20ARRL/Board%20Meetings/2010%20July%20BOD%20minutes%20FINAL.pdf  
(The relevant item is #25 on page 5.)

The previous wording of section 1.12 was:

"Above 300 GHz contacts are permitted for contest credit only between 
licensed amateurs using coherent radiation on transmission (for example, 
LASER) and employing at least one stage of electronic detection on 
receive."

The adopted change is as follows:

"Above 300 GHz, contacts are permitted for contest credit only between 
licensed amateurs using monochromatic signal sources (for example, LASER 
and LED) and employing at least one stage of electronic detection on 
receive. LASER usage is restricted to ANSI Z136 Class I, II, IIa, and 
IIIa (i.e., output power is less than 5mW)."

As can clearly be seen, the changes allow sources of light other than 
lasers - including LEDs.  This wording could also be taken to also allow 
various types of gas-discharge lamps - perhaps even filtered multi-line 
emitters.  It does seem to disallow direct use of broadband "thermal" 
sources such as tungsten lamps, however.

What does this mean?

It could be argued that the previous limitation to coherent sources - 
which limited one to the use of lasers at optical wavelengths - put a 
practical limit on how much power one could run when considering factors 
such as safety and practicality:  Without doubt, a high-power laser 
(e.g. more than a few 10's of milliwatts) is a very dangerous piece of 
equipment and should be treated with respect akin to an exposed plate 
supply - albeit one that can reach out some distance from its source and 
cause harm!  If one needed more optical power to meet a link budget than 
a modest-power laser could provide, your options were limited.

The addition of other types of light sources expands the possibilities, 
allowing other types optics to be used (e.g. non diffraction-limited) 
which greatly can be used to greatly increase the practical exit 
aperture of a transmitter, decreasing the power density and thus the 
potential hazards to the operators and others that might encounter the 
beam while simultaneously increasing the total amount of power one can 
radiate safely.

Now, some might say that the new rule is overly restrictive:  I, 
personally, would have preferred to see wording that required that laser 
operations be conducted in accordance such-and-such a set of safety 
guidelines, but one must also keep in mind that contest rules should be 
kept rather straightforward and simple - and the "5 milliwatt" 
restriction *does* do this.  I would also would have preferred that 
"non-monochromatic" signal sources (such as thermal) be permitted, but 
then again...

Finally, keep in mind that these rules apply ONLY to ARRL contests and 
shouldn't limit one's imagination:  If you wish to conduct experiments 
using techniques or gear that doesn't fall within the scope of the rule, 
one should feel free to do so safely!  It is with such experimentation 
that new techniques are developed and perhaps, one day, may be included 
in the contest rules!

73,
.
Clint
KA7OEI

***

Additional comments:

One change that, on the surface, appears to be significant is the 
specific limitation of laser output to the classes mentioned above - 
that is to power levels < 5 milliwatts.

Generally speaking, regulation of laser operation (in the U.S., at 
least) falls within the purview of the FDA and in very general terms, 
operations of lasers >= 5 milliwatts (that is, Class IIIb and Class IV) 
have some rather specific restrictions when operated in "uncontrolled" 
environments.  For a taste of some of the things that should be 
considered, look at these documents:

http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfCFR/CFRSearch.cfm?FR=1040.10 

http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/HomeBusinessandEntertainment/LaserProductsandInstruments/ucm116373.htm 


It is worth noting that there is a "new" classification system which 
includes different nomenclature  (Arabic rather than Roman numerals and 
additional classes such as 1M, 2M, 3R, etc.)  In general, however, the 
"new" and "old" designations equate fairly closely to each other.

Now, whether or not it's "legal" to operate a Class IIIb or IV laser 
"out in the open" without jumping through a bunch of hoops is a bit 
fuzzier - and, to some extent, it depends on what the laser is used for 
as noted by the second of the FDA links above (that is, calling a "laser 
pointer" can put it in a different class than calling it something else.)

While the Federal laws are one thing, many states have their own laws - 
for some example, see this list:

http://www.laserpointersafety.com/rules-general/uslaws/uslaws.html

Other miscellaneous  laser safety related links:

http://www.als.lbl.gov/als/safety/laser_class.html
http://www.des.umd.edu/rs/laser/laserplan.pdf
http://www.utexas.edu/safety/ehs/lasers/Laser%20Safety%20Handbook-tnt.pdf
http://blink.ucsd.edu/safety/research-lab/lasers/control.html

As can be seen, the U.S. rules governing such things are in a state of 
flux and can be rather vague and confusing while the precautions taken 
by those who use higher-power lasers are quite comprehensive, indicating 
obvious respect for the hazards involved.

I suspect that the 5 milliwatt limitation was imposed as a matter of 
practicality and safety:  A seemingly modest power increase from 5 to 50 
milliwatts seems to disproportionally increase the hazard of the beam 
while a power level of 500 milliwatts is just plain hazardous and 
demands considerable respect from those who work with such lasers on a 
regular basis!

***