Telescope Reviews: Pimp my Gallileoscope

Many amateurs make use of a green laser pointer. Green is used because the eye is more sensitive to this wavelength than the common red laser pointer. If skies are dark enough, a 5 milliwatt green laser pointer is sufficient power. To have a red laser pointer to be as visible, it has to be much more powerful.

USE:- If the laser beam is pointed at the dark sky when your eyes have adjusted, the beam hits all the dust and fine water droplets in the sky and scatters back so one can see the beam going off into the sky - sort of Star Wars Light Sabre-like! If people are standing close to the person with the laser (within say 10 feet) they also see the beam. The trigonometry is such that they all perceive the end of the laser beam to be at the same infinite point. So if the person holding it points it so that the end of the beam seems to them to be on a star, the others see the same thing. So it is really useful for someone to show other people things in the sky or to indicate a point they want to look at.

Now, if you mount a laser beam on your telescope (there are special laser pointer holders that you can buy) and align it properly with the axis of the scope (like aligning the Daisy Dot finder) then, if you move the scope so the laser beam seems to end at the object of interest, it will be in the field of view of the scope. It is really easy.

One point to mention. Green lasers stop "lasing" at low temperatures. My experience that this is down around a few degrees above freezing (in my case around 3-5 deg Celsius). Many people think it is their batteries going flat or cold, but it is the laser itself. You need to keep it warm. Best way is, between uses, put it in an inside pocket against your body.

SAFETY:- Which leads us to safety. A mis-used green laser pointer can be a significant problem. Shone into someone's eyes can cause a problem. Usually the blink reflex prevents serious damage, but with the more powerful lasers (I have seen these lasers sold up to 100 milliwatts), who knows. At least they will distract a pilot or a car driver and un-intelligent people have done this with them. They should not be in the hands of children or anyone who does not understand and won't use them responsibly and safely. Hence keeping it in your pocket between uses so no one else touches it. A second problem is avoiding getting thumped by an astrophotographer whose image was ruined by the flash of a green laser pointer beam through his/her field of view. Be careful if others are taking images.

LAW:- In various jurisdictions, there are laws that deal with these devices. For example, in my State of Australia, any hand-held laser pointer of greater than 1 milliwatt emittable power is a "prohibited weapon". I have a licence from the Police to possess and use my 5 milliwatt laser pointer and I had to justify its use and adhere to certain conditions and pay a licence fee.

Do a bit of goggling of green lasers and astronomy and safety and law and you'll find all you need.

Edited by erick (08/15/09 06:20 PM)