Josh is right, from my experience you just need to keep the laser (batteries) warm unless actually using it. I typically use alkaline cells in my smaller unit and a set lasts a couple of months even under frequent use. I use two. One is a 20mW that looks like a typical green laser pointer but is much brighter, the other is a 100mW unit (tested at 112mW) that never seems to have cold issues. It uses a CR123 battery however, not AA cells. It is visually two to three times the brightness of the 20mW unit. On Sat, Jan 19, 2013 at 9:57 PM, Josh <mountaindrifter@gmail.com> wrote:

I think performance in cold temperatures is more an issue with the batteries.

Bill, I got mine on-line from two different vendors some years ago, pre-divorce when I actually had pocket money. The 100mW was purchased from Destructive Gear ($300, with a $100 discount coupon, reg. $400), the 20mW unit from Beta Electronics (about $120 if memory serves). Recent searches on both websites don't show those lasers anymore, however. I think Seth Jarvis picked-up one of the 100mW units as well, perhaps he can comment on that one too. Yes, it will pop a balloon and ignite a match head. Two tasks so vital for amateur astronomy. ;-) I never saw one of the lasers offered at the club meeting. Anybody get one and have some feedback? Are they 5mW or less output? On Mon, Jan 21, 2013 at 7:41 AM, william baker <baker464b@yahoo.com> wrote:

Will the gentleman who is the wholesaler for these laser pointers be at the next meeting? I would like to purchase one or two.

"Laser envy" LOL! On Mon, Jan 21, 2013 at 10:31 AM, Hutchings, Mat <mat.hutchings@siemens.com>wrote:

I still have a serious case of laser envy whenever I use it to show the night sky. Invariably someone will say something like "here use mine, it's brighter"

I picked up two green lasers from laserpointerpro.com. Would I buy from them again? Hmmm... Interesting question. One was a 400 mw (tests out at 350), and the other was a 200 mw (tests out at 175). Both use the 18650 3.7V lithium rechargeable battery. Both came directly from China, and I paid for them with PayPal, which is a little scary when dealing with overseas vendors. The 18650 battery charger that came with the 400 mw laser died the second time I tried to use it. Fortunately, I'd purchased two extra batteries and another charger from Amazon, so I'm not without a charger. The vendor also didn't include the battery with the 400 mw laser, and I had to email him for weeks to get him to deliver what the online ad promised was included. Both lasers are kick-butt awesome, especially the 400 mw - it's a monster and will burn your skin fast. It does require a special key to operate which is a bit of a hassle. You do NOT want to put this in the hands of kids. I find that for star parties the "little" 200 mw laser works very well and is convenient to use. I only use the 400 when I have a big group of people around me and I'm in the mood to show off a bit and make sure everyone sees what I'm pointing at. Neither laser would be appropriate if there were a bunch of other telescopes around me. Probably have to drop down to a 20 mw, and even then there would be complaints from other folks, I suspect. I've never had either the 200 or 400 laser out in the bitter cold that we're experiencing here these days (because I'm not crazy), but from my experience with other lasers I think the advice given thus far - use fresh batteries and keep them warm - is smart. ***What you do _NOT_ want to do is buy a laser that claims to have >50 mw output but only runs on the puny single battery that's about half the size of the CR123. I've got a 100 mw pen-sized green laser that uses two AAA batteries, and while it's great when the batteries are fresh, it goes through batteries really fast.

...

...

...

Big power requires big batteries.<<< It's that simple.

In terms of online buying from places that ship directly from China - caveat emptor. Seth -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Chuck Hards Sent: Monday, January 21, 2013 8:01 AM To: Utah Astronomy Subject: Re: [Utah-astronomy] laser pointers Bill, I got mine on-line from two different vendors some years ago, pre-divorce when I actually had pocket money. The 100mW was purchased from Destructive Gear ($300, with a $100 discount coupon, reg. $400), the 20mW unit from Beta Electronics (about $120 if memory serves). Recent searches on both websites don't show those lasers anymore, however. I think Seth Jarvis picked-up one of the 100mW units as well, perhaps he can comment on that one too. Yes, it will pop a balloon and ignite a match head. Two tasks so vital for amateur astronomy. ;-) I never saw one of the lasers offered at the club meeting. Anybody get one and have some feedback? Are they 5mW or less output? On Mon, Jan 21, 2013 at 7:41 AM, william baker <baker464b@yahoo.com> wrote:

Will the gentleman who is the wholesaler for these laser pointers be at the next meeting? I would like to purchase one or two.

_______________________________________________ Utah-Astronomy mailing list http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Send messages to the list to Utah-Astronomy@mailman.xmission.com The Utah-Astronomy mailing list is not affiliated with any astronomy club. To unsubscribe go to: http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Then enter your email address in the space provided and click on "Unsubscribe or edit options".

I spoke with him after the last meeting and he assured me he would have the box of laser pointers ($10 each) at the next meeting. I believe these are the garden-variety legal, <5mw green lasers most of us use with success (when the sky isn't too light-polluted). ________________________________ From: william baker <baker464b@yahoo.com> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Sent: Monday, January 21, 2013 7:41 AM Subject: Re: [Utah-astronomy] laser pointers Will the gentleman who is the wholesaler for these laser pointers be at the next meeting?  I would like to purchase one or two. Bill ________________________________ From: Chuck Hards <chuck.hards@gmail.com> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Sent: Monday, January 21, 2013 7:17 AM Subject: Re: [Utah-astronomy] laser pointers Josh is right, from my experience you just need to keep the laser (batteries) warm unless actually using it.  I typically use alkaline cells in my smaller unit and a set lasts a couple of months even under frequent use. I use two.  One is a 20mW that looks like a typical green laser pointer but is much brighter, the other is a 100mW unit (tested at 112mW) that never seems to have cold issues.  It uses a CR123 battery however, not AA cells. It is visually two to three times the brightness of the 20mW unit. On Sat, Jan 19, 2013 at 9:57 PM, Josh <mountaindrifter@gmail.com> wrote:

I think performance in cold temperatures is more an issue with the batteries.

Utah-Astronomy mailing list http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Send messages to the list to Utah-Astronomy@mailman.xmission.com The Utah-Astronomy mailing list is not affiliated with any astronomy club. To unsubscribe go to: http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Then enter your email address in the space provided and click on "Unsubscribe or edit options". _______________________________________________ Utah-Astronomy mailing list http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Send messages to the list to Utah-Astronomy@mailman.xmission.com The Utah-Astronomy mailing list is not affiliated with any astronomy club. To unsubscribe go to: http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Then enter your email address in the space provided and click on "Unsubscribe or edit options".

Rich's mention of the legality of these lasers makes me wonder about the previous discussion re. 200 or 400-mw lasers. Any comments? ________________________________ From: Richard Tenney <retenney@yahoo.com> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Sent: Tuesday, January 22, 2013 9:39 AM Subject: Re: [Utah-astronomy] laser pointers I spoke with him after the last meeting and he assured me he would have the box of laser pointers ($10 each) at the next meeting. I believe these are the garden-variety legal, <5mw green lasers most of us use with success (when the sky isn't too light-polluted). ________________________________ From: william baker <baker464b@yahoo.com> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Sent: Monday, January 21, 2013 7:41 AM Subject: Re: [Utah-astronomy] laser pointers Will the gentleman who is the wholesaler for these laser pointers be at the next meeting?  I would like to purchase one or two. Bill ________________________________ From: Chuck Hards <chuck.hards@gmail.com> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Sent: Monday, January 21, 2013 7:17 AM Subject: Re: [Utah-astronomy] laser pointers Josh is right, from my experience you just need to keep the laser (batteries) warm unless actually using it.  I typically use alkaline cells in my smaller unit and a set lasts a couple of months even under frequent use. I use two.  One is a 20mW that looks like a typical green laser pointer but is much brighter, the other is a 100mW unit (tested at 112mW) that never seems to have cold issues.  It uses a CR123 battery however, not AA cells. It is visually two to three times the brightness of the 20mW unit. On Sat, Jan 19, 2013 at 9:57 PM, Josh <mountaindrifter@gmail.com> wrote:

I think performance in cold temperatures is more an issue with the batteries.

Utah-Astronomy mailing list http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Send messages to the list to Utah-Astronomy@mailman.xmission.com The Utah-Astronomy mailing list is not affiliated with any astronomy club. To unsubscribe go to: http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Then enter your email address in the space provided and click on "Unsubscribe or edit options". _______________________________________________ Utah-Astronomy mailing list http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Send messages to the list to Utah-Astronomy@mailman.xmission.com The Utah-Astronomy mailing list is not affiliated with any astronomy club. To unsubscribe go to: http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Then enter your email address in the space provided and click on "Unsubscribe or edit options". _______________________________________________ Utah-Astronomy mailing list http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Send messages to the list to Utah-Astronomy@mailman.xmission.com The Utah-Astronomy mailing list is not affiliated with any astronomy club. To unsubscribe go to: http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Then enter your email address in the space provided and click on "Unsubscribe or edit options".

Unfortunately the limitation of laser pointers to <5mW makes them useless for astronomy much of the time. A 1mW laser isn't worth owning as an astro-pointer. The regulations obviously are aimed at classroom and indoor lecture use, where the dot itself is used as a highlighter, not the beam. Low-powered lasers excell at this task, but they fail as star-pointers. Used astronomically, many times a 5mW laser beam must be viewed close to it's axis to be seen at all, especially under less-than-ideal sky conditions including moderate light pollution. That makes them useless for large groups (star parties), as Seth Jarvis and others on this list can attest. Not everyone can stand right behind the person with the pointer. I would hope that *everyone* using lasers as instructional tools would use them safely- not just those who opt for a higher-powered unit that actually works well as a star-pointer. Even a $2 keychain red laser can cause eye damage. In the state of Utah, as I've posted here before, it is illegal to aim a laser at a person, vehicle (that includes aircraft), or animal, regardless of power output or wavelength (color). FWIW, the laser mounted on the 32" scope at SPOC is rated at 10mW and is just bright enough to be seen under most conditions. I bought that one on behalf of the club after disappointment with several lasers of ~5mW output. Counterintuitively, under the darkest, most transparent skies, even the low-power units aren't very visible. To see the beam itself, you need particulates suspended in the air for the beam to illuminate. Excellent transparency just means you need a higher powered unit in order for the beam to be seen. Strictly on the criteria of visibility and useability, I would not not recommend a laser intended for use as a star-pointer to be rated at less than 10mW, regardless of low cost. Of course I don't advise anyone to break the law. I'm just stating an opinion as to useability in our application vs. laser output. Finally, know that just because the label on the laser states 5mW, it could in fact be much brighter- or dimmer. There is a large spread of output among diodes of the same manufacturing batch. Many are higher, many are lower. The 5mW rating is an average for the diode design. My 20mW laser (bench-tested) uses the same diode as some 5mW units yet puts out ~20.4mW. This explains why two identical lasers can often display different brightness to the eye. So while it's purchase was legal, it's actual output is higher than the law allows for. (Mine was purchased as a "best of the batch" by a seller who tests each unit individually. Few vendors do on the lower-powered lasers these days.) Good luck on your laser decision. Caveat emptor, and be safe no matter how bright or dim your laser is. On Wed, Jan 23, 2013 at 10:13 PM, Ivo Stutznegger <ics_ute@yahoo.com> wrote:

Laser products promoted for pointing and demonstration purposes are limited to hazard Class IIIa by FDA regulation. This means that pointers are limited to 5 milliwatts output power in the visible wavelength range from 400 to 710 nanometers. (Common DPSS green lasers are 532 nanometers). European and international (IEC) standards for laser classification were revised in 2001 eliminating the Class 3a designation and basically calling for laser pointer devices to be in the Class 2M or lower designation limiting output to 1 mW. The reason for these standards are safety. Lasers that emit between 5mW and 500mW output power are in Class IIIb (or IEC Class 3B). Class IIIb lasers cannot legally be promoted as laser pointers or demonstration laser products in the US. Radiation in this class is considered very likely to be dangerous. As the FDA puts it,"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." My advice to anyone that chooses to own and use a handheld laser of >5 milliwatt output is to make sure you are extremely careful or you are putting yourself and those around you at risk of eye damage. I would also note to those interested in ordering powerful laser pointers from Chinese suppliers that the FDA considers Class IIIb hand-held lasers too dangerous for use as pointers or amusement articles and subject to detention and seizure by the U.S. Customs and Border Protection when imported. Additional information can be found at the FDAs website at: http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm166649.htm

A MW laser, YOWZA, I'm sure that would function just fine in cold weather... Mat -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Larry Holmes Sent: Monday, January 21, 2013 5:09 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] laser pointers Kim, I have a picture of, I believe, a megawatt (I could be way off, maybe Charlie remembers) laser that was used, in conjunction with2 very high power zenon lamps, to try to light up the space shuttle. Only problem is that it is on my IPad, and unless you have some apple equipment, I would not know how to send it to you. 73 On 1/19/2013 11:33 AM, Kim wrote:

Hi all. Anyone have a recommendation for a laser pointer that functions well in cold temperatures?

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As for keeping it warm, would it be feasible to rubber-band a couple hand warmers around it?   ----- Original Message ----- From: Kim <kimharch@cut.net> To: 'Utah Astronomy' <utah-astronomy@mailman.xmission.com> Cc: Sent: Tuesday, January 22, 2013 8:34 AM Subject: Re: [Utah-astronomy] laser pointers Thanks to all for advice. I was hoping that technology had progressed to the point that keeping the laser warm (just awkward fishing it out under three or four layers of clothing) or buying expensive batteries weren't the only options. Josh shared some information about Optotronics products (thanks Josh); here's the link: http://www.optotronics.com/green-laser-pointers.php. I'm leaning toward trying out the 30mW model. I'm afraid that the 175mW model might be a bit too conspicuous. ;-) Has anyone used Optotronics products? -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Larry Holmes Sent: Monday, January 21, 2013 3:09 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] laser pointers Kim, I have a picture of, I believe, a  megawatt (I could be way off, maybe Charlie remembers) laser that was used, in conjunction with2 very high power zenon lamps, to try to light up the space shuttle.  Only problem is that it is on my IPad, and unless you have some apple equipment, I would not know how to send it to you.  73 _______________________________________________ Utah-Astronomy mailing list http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Send messages to the list to Utah-Astronomy@mailman.xmission.com The Utah-Astronomy mailing list is not affiliated with any astronomy club. To unsubscribe go to: http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Then enter your email address in the space provided and click on "Unsubscribe or edit options".

You could slip a hand-warmer into an outer front vest pocket, in a sock or two. Then just put the laser next to it, like a pen in a front shirt pocket. On Tue, Jan 22, 2013 at 1:47 PM, Scott Catron <zaui@yahoo.com> wrote:

As for keeping it warm, would it be feasible to rubber-band a couple hand warmers around it?

Yes  - sorry, wasn't clear - the iron-in-a-bag type that you have to shake to activate. They last for several hours.   ----- Original Message ----- From: Chuck Hards <chuck.hards@gmail.com> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Cc: Sent: Tuesday, January 22, 2013 2:15 PM Subject: Re: [Utah-astronomy] laser pointers OK, you were talking about the chemical type in a plastic bag.  No sock needed for that.  I was thinking the old fashioned lighter-fluid catalytic type that got really toasty. On Tue, Jan 22, 2013 at 2:13 PM, Chuck Hards <chuck.hards@gmail.com> wrote:

You could slip a hand-warmer into an outer front vest pocket, in a sock or two.  Then just put the laser next to it, like a pen in a front shirt pocket.

On Tue, Jan 22, 2013 at 1:47 PM, Scott Catron <zaui@yahoo.com> wrote:

...

As for keeping it warm, would it be feasible to rubber-band a couple hand warmers around it?

_______________________________________________ Utah-Astronomy mailing list http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Send messages to the list to Utah-Astronomy@mailman.xmission.com The Utah-Astronomy mailing list is not affiliated with any astronomy club. To unsubscribe go to: http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Then enter your email address in the space provided and click on "Unsubscribe or edit options".