Laser pointer question

I have a question about laser pointers ... I want to use one in
astronomy.
Some I see are 10 mw ... others 10mw ... what does this mean to me,
very much a layman ... that one is brighter? point further? last
longer on their batteries?
Any suggestions on who to buy from?
Thanks

They are the same, be it written "10mw" or "10 mw", it means the same, 10
milliwatt output, in other words, less than a watt of power output.


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wrote in message
...


I have a question about laser pointers ... I want to use one in
astronomy.
Some I see are 10 mw ... others 10mw ... what does this mean to me,
very much a layman ... that one is brighter? point further? last
longer on their batteries?
Any suggestions on who to buy from?
Thanks

Coorect. And watch out for the ones with ratings in Mw.. way too
powerful!

Matthew Ota

Such as the one on the ADM-Aeolus satellite!

Roger Persson

Matthew Ota wrote:
Coorect. And watch out for the ones with ratings in Mw.. way too
powerful!

On Sat, 13 May 2006 18:06:58 -0400, wrote:

I have a question about laser pointers ... I want to use one in
astronomy.
Some I see are 10 mw ... others 10mw ... what does this mean to me,
very much a layman ... that one is brighter? point further? last
longer on their batteries?

Lasers are rated in milliwatts, abbreviated mW. The higher the value,
the brighter. Keep in mind that most laser pointers are labeled as Class
3a, which means they have a maximum output of 5mW (which is generally
quite safe). Some lasers have been adjusted to deliver more power. If
so, they should NOT be labeled Class 3a, although they often are. In the
U.S., it is perfectly legal to sell, buy, or operate higher power lasers
(but they need to be properly labeled). The responsibility is on the
operator to operate safely. Certainly there should be little problem
using a 10-15mW green laser, although this is starting to get into the
range where eye damage can occur. There is little need for more than 5mW
unless you are operating it (as a star pointer) at high altitude under
dry conditions. A 5mW green beam is very visible under most
environments.

BTW, you can only compare power to brightness for lasers of the same
wavelength. A 5mW green laser will appear much brighter than a 5mW red
laser.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

wrote in message
...


I have a question about laser pointers ... I want to use one in
astronomy.
Some I see are 10 mw ... others 10mw ... what does this mean to me,
very much a layman ... that one is brighter? point further? last
longer on their batteries?
Any suggestions on who to buy from?
Thanks

Anything called a "pointer" in the USA is limited to 5 mW.
The proper nomenclature 'mW', m=milli and W=James Watt.
Try eBay as there are many green pointers offered and I would not
pay more than $50 for one. Also don't buy one that boasts high power (50
mW)
as these are usually from off shore and you risk your purchase being
confiscated at the boarder once they have your money
They are all DPSS lasers and the 10 mW rating is probably the maximum
CDRH rating and means very little.
For more info on lasers, check here
http://www.repairfaq.org/sam/lasersam.htm


mike

Any suggestions on who to buy from?


I have the $55 model from z-bolt.com. Works good, quick delivery.

-Florian

wrote in news:g2mc621di9105hl707csodk9frsne23q22@
4ax.com:



I have a question about laser pointers ... I want to use one in
astronomy.
Some I see are 10 mw ... others 10mw ... what does this mean to me,
very much a layman ... that one is brighter? point further? last
longer on their batteries?
Any suggestions on who to buy from?
Thanks

The following applies to the USA.

1 - The term "laser pointer" has a very specific legal definition.

2 - Laser pointers must be less than 5mW. Anything higher cannot
legally be called a "laser pointer".

3 - It is illegal to sell/import/manufacture laser pointers of higher
power.

4 - Using ANY laser (pointer or not) of more than 5mW in a public
place is illegal without a variance.

5 - Any laser of more than 5mW used in public must meet very specific
design requirements to be legal, and a "laser pointer" as designed
does not meet those requirements.

Just because a seller calls it an "OEM module" does not mean it
can be legally used in public. Not only is the seller likely breaking
the law (see #3 above), but your use of the "OEM module" is still
bound by rules 4 & 5 above.

It is not illegal to purchase a legal laser pointer and modify it
yourself for personal use to higher than 5mW. However, you are still
bound to rules 3, 4 & 5 above.

Keep it legal. Keep it safe. Do not support illegal "laser pointer"
retailers/manufacturers by buying their "product." Some countries
already ban laser pointers outright. Don't let the idiots who are
only interested in turning a quick buck ruin it for everyone else.

Here's links to more information and to the legal code:

"Important Information for Laser Pointer Manufacturers"
http://www.fda.gov/cdrh/radhlth/lpm.html

"Sec. 1040.10 Laser products"
http://www.accessdata.fda.gov/script...Search.cfm?fr=
1040.10

"Sec. 1040.11 Specific purpose laser products"
http://www.accessdata.fda.gov/script...Search.cfm?fr=
1040.11

Brian
--
http://www.skywise711.com - Lasers, Seismology, Astronomy, Skepticism
Seismic FAQ: http://www.skywise711.com/SeismicFAQ/SeismicFAQ.html
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Sed quis custodiet ipsos Custodes?

On Sun, 14 May 2006 00:54:45 -0000, Skywise
wrote:

4 - Using ANY laser (pointer or not) of more than 5mW in a public
place is illegal without a variance.

5 - Any laser of more than 5mW used in public must meet very specific
design requirements to be legal, and a "laser pointer" as designed
does not meet those requirements.

This isn't quite true. The rules control the marketing of lasers, not
the use. There is no federal regulation preventing you from using a
Class 3b laser in public, including a pointer (even though a Class 3b
pointer could not be legally sold as such). I'll qualify that last
statement by pointing out that there are federal regulations that manage
if and how lasers can be operated in specific, sensitive locations, such
as the vicinity of airports, and in cases where air traffic could be
affected. There has also been some extralegal prosecution using
"anything goes" Homeland Security rules.

Most laws that could prohibit the use of a high power laser outdoors are
purely local, not federal.


Just because a seller calls it an "OEM module" does not mean it
can be legally used in public. Not only is the seller likely breaking
the law (see #3 above), but your use of the "OEM module" is still
bound by rules 4 & 5 above.

The seller may be breaking the law, but not necessarily the user. The
FDA doesn't mandate use.


It is not illegal to purchase a legal laser pointer and modify it
yourself for personal use to higher than 5mW. However, you are still
bound to rules 3, 4 & 5 above.

Nope. Only if it's your business to modify lasers.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

Chris L Peterson wrote in
:

On Sun, 14 May 2006 00:54:45 -0000, Skywise
wrote:

4 - Using ANY laser (pointer or not) of more than 5mW in a public
place is illegal without a variance.

5 - Any laser of more than 5mW used in public must meet very specific
design requirements to be legal, and a "laser pointer" as designed
does not meet those requirements.

This isn't quite true. The rules control the marketing of lasers, not
the use. There is no federal regulation preventing you from using a
Class 3b laser in public, including a pointer (even though a Class 3b
pointer could not be legally sold as such). I'll qualify that last
statement by pointing out that there are federal regulations that manage
if and how lasers can be operated in specific, sensitive locations, such
as the vicinity of airports, and in cases where air traffic could be
affected. There has also been some extralegal prosecution using
"anything goes" Homeland Security rules.

Most laws that could prohibit the use of a high power laser outdoors are
purely local, not federal.

Title 21 Code of Federal Regulations, section 1040.10.

Lasers are "radiation emitting devices" and fall under the jurisdiction
of the Center for Devices and Radiological Health (CDRH) of the Food
and Drug Administration (FDA).

So much for the the "local not federal" argument.

21CFR1040.10(b)(13) -
'Demonstration laser product' means any laser product
manufactured, designed, intended, or promoted for purposes of
demonstration, entertainment, advertising display, or artistic
composition. The term demonstration laser product does not
apply to laser products which are not manufactured, designed,
intended, or promoted for such purposes, even though they may
be used for those purposes or are intended to demonstrate other
applications.

21CFR1040.10(b)(39) -
'Surveying, leveling, or alignment laser product' means a laser
product manufactured, designed, intended or promoted for one or
more of the following uses:

(i) Determining and delineating the form, extent, or position of
a point, body, or area by taking angular measurement.

(ii) Positioning or adjusting parts in proper relation to one
another.

(iii) Defining a plane, level, elevation, or straight line.

A laser pointer falls under either of these definitions. The above
defintions define the _use_ of the laser. Further supporting evidence
is from the following document on the FDA website:

"Important Information for Laser Pointer Manufacturers"
http://www.fda.gov/cdrh/radhlth/lpm.html

Continuing my quotations of the code...

21CFR1040.11(b) -
'Surveying, leveling, and alignment laser products.' Each
surveying, leveling. or alignment laser product shall comply
with all of the applicable requirements of 1040.10 for a
Class I, IIa, II or IIIa laser product and shall not permit
human access to laser radiation in excess of the accessible
emission limits of Class IIIa.

21CFR1040.11(c) -
'Demonstration laser products.' Each demonstration laser
product shall comply with all of the applicable requirements
of 1040.10 for a Class I, IIa, II, or IIIa laser product and
shall not permit human access to laser radiation in excess of
the accessible emission limits of Class I and, if applicable,
Class IIa, Class II, or Class IIIa.

The above codes place limits on the amount of power emitted by
laser pointers. This is also outlined in the "Important Information"
document linked above.

The highest class listed in both paragraphs above is Class IIIa.

21CFR1040.10(b)(8) -
'Class IIIa laser product' means any laser product that
permits human access during operation to levels of visible
laser radiation in excess of the accessible emission limits
contained in table II, but does not permit human access
during operation to levels of laser radiation in excess of
the accessible emission limits contained in table III-A of
paragraph (d) of this section.

Here's a direct link on the FDA's website to a PDF version of this
document:

http://a257.g.akamaitech.net/7/257/2...ess.gpo.gov/ec
fr/graphics/pdfs/er01fe93.033.pdf

Since it's a long URL, here's a TinyURL version:
http://tinyurl.com/q4dc3

But here's a text version:

Class IIIa accessible emission limits are identitical to Class I
accessible emission limits except within the following range of
wavelengths and emission durations:

Wavelength | Emission | Class IIIa-Accessible emission limits
(nanometers)| Duration | (value) | (unit) | (quantity)*
| (seconds | | |
----------------------------------------------------------------
400 but | 3.8x10e-4 | 5.0x10e-3 | W | radiant power
= 700 | | | |
----------------------------------------------------------------
*Measurment parameters and test conditions shall be in accordance
with paragraphs (d)(1), (2), (3), (4), and (e) of this section.

400 to 700 nanomaters is the visible light range, and any exposures
to laser light within this range for more than 0.00038 seconds must
not exceed 5 milliwatts.

So there you have it. The _federal_ code governing the _use_ of
lasers as applicable to laser pointers. You are not permitted to
use a laser of Class IIIb or above where it is possible for people
to come into contact with laser emission.


Just because a seller calls it an "OEM module" does not mean it
can be legally used in public. Not only is the seller likely breaking
the law (see #3 above), but your use of the "OEM module" is still
bound by rules 4 & 5 above.

The seller may be breaking the law, but not necessarily the user. The
FDA doesn't mandate use.

Yes they do. See my argument above.

Also, from the "Important Information" document linked above,

What is the problem with more powerful Class IIIb lasers being
promoted and sold as pointers?

...

Irresponsible use of more powerful laser pointers poses a
significant risk of injury to the people exposed. Persons who
misuse or irresponsibly use lasers are open to personal liability
and prosecution.

So, you go using a Class IIIb laser pointer and it touches me, I
can "sue your ass off."


It is not illegal to purchase a legal laser pointer and modify it
yourself for personal use to higher than 5mW. However, you are still
bound to rules 3, 4 & 5 above.

Nope. Only if it's your business to modify lasers.

Yes you are. See my arguments above.

Chris, in my first post I provided links to all the above code
and the "Important Information" document on the FDA website.
You should have taken the time to read at least the "Important
Information" document before replying. Much of what I said above
is outlined in that document.

Also, you should have looked at my signature lines. You'd see
that part of my website is dedicated to my hobby of lasers. I
have had an interest in lasers since I was a kid, and have been
hard core about my hobby for at least ten years now. So although
I am not a lawyer, and I am not a laser 'professional', I do
know what I am talking about in this case.

If you have further questions, I invite you over to the newsgroup
alt.lasers. There are a few professional laser show personnel
over there who would be happy to discuss the use of lasers in
public with you.

Brian
--
http://www.skywise711.com - Lasers, Seismology, Astronomy, Skepticism
Seismic FAQ: http://www.skywise711.com/SeismicFAQ/SeismicFAQ.html
Quake "predictions": http://www.skywise711.com/quakes/EQDB/index.html
Sed quis custodiet ipsos Custodes?