Brisbane - green laser pointer to borrow for school viewing
G'day. I've been talked into taking my dob along to son's class for a planet/moon viewing night. They're in Prep, so pretty young kids. I was thinking about using a laser pointer to show them the planets, some basic constellations etc. But I don't have a laser pointer. Does anyone have one that I may be able to borrow for a night? Currently thinking the weekend of the first quarter moon in October - so what's that, around 20/10?
G'day. I've been talked into taking my dob along to son's class for a planet/moon viewing night. They're in Prep, so pretty young kids. I was thinking about using a laser pointer to show them the planets, some basic constellations etc. But I don't have a laser pointer. Does anyone have one that I may be able to borrow for a night? Currently thinking the weekend of the first quarter moon in October - so what's that, around 20/10?
Apparently I need to check into the legality of their use in Qld.
Edit - looks like up to 1mW are fine, over that need to be a member of Astro Society (IIS count? ) or occupational reasons.
Edit 2 - just ordered one off Trevor's ebay link. As I said, didn't realise they were that cheap. Should be fine for a night's use.
I took my 8yo niece out the in the backyard (city central) about 2 weeks ago and used it to point out the usual things, she was easily able to follow where I was pointing.
Batteries (2x AAA) seem to last about 20mins of constant use before starting to fade. Reality is that you use it for 15sec on, 1 minute off.
Apparently I need to check into the legality of their use in Qld.
Edit - looks like up to 1mW are fine, over that need to be a member of Astro Society (IIS count? ) or occupational reasons.
Edit 2 - just ordered one off Trevor's ebay link. As I said, didn't realise they were that cheap. Should be fine for a night's use.
Hi Troy
From what I can find having a quick look, lasers for astronomical use must be below 20 milliwatts and used by a person associated with a recognised astronomical group listed on the QPS website as an approved organisation. Lasers over 1 mW are a restricted weapon under the Act. There are also storage requirements under the Act. The Document I found was 2012 but is a QPS publication.
A couple of things to be aware of Troy.
Cheap eBay pointers seldom are the power they state.
Usually they understate the mW to get around eBay rules.
Even if they state 1mW, it most probably won't be.
More like >20mW.
Also, the type of green laser is something to watch too.
532nm (green) (DPSS) uses 808nm IR passing through a neodymium crystal which converts to 1064nm IR, then passes through a frequency doubling crystal to produce 532nm.
Good quality 532nm greens then have a IR filter to stop harmful IR (invisible to the eye) leakage.
Cheap ones don't and are emitting this harmful IR (unknown to the user) which could be several order of magnitude above the stated power of the 532nm visible green beam.
What you need is a 510nm or 520nm green which are Direct diode lasers and thus do not use IR to produce the green beam.
Basically, your looking at around 10mW minimum as a viable green pointer.
The alternative is to go with the safer 1mW or 5mW red pointers that are dimmer (yet still visible) and don't suffer from IR problems either.
Just don't trust the power ratings of the cheap eBay lasers, no matter what they claim.
The only way to know the power of a laser is to use a proper Laser Power Meter.
You can't judge the power by looking at the beam.
Also anything greater than 5mW is harmful and dangerous to the eye as the blink reflex is much too slow to avoid damage by a stray beam hit.
This is why laser goggles are a must, but this defeats the purpose of using them as astro pointers.
) or occupational reasons.
