What means "650 nm or 635nm"?
"nm" stands for "Nanometer" and is a length measurement. 1nm = 10^-9m = 1/1000000 mm. Light is a electromagnetical radiation and the number corresponds to the wavelength of the light - each wavelength stands for a certain colour. Light with a short wavelength is for example blue, a long wavelength is red. The human eye has different sensivity for colors and we feel a yellow or green spot to be brighter (if the output power is the same). I.e. we have the impression a green pointer is more intense than a red one, although the output power is the same. A 635nm pointer appears to be brighter than a 650 nm pointer.

What range covers the beam of a laser pointer?
It is difficult to answer this question seriously. The beam travels until it hits a hindrance or the energy got absorbed by particles in the air. Additionally the beam expands with the distance (although the divergence of a laser is low) and it is difficult to find the beam because of its (small) size, i.e. it gets difficult to find the spot.

A pointer manufacturer: The range of a 650nm pointer is up to 150m, a 635nm pointer goes up to 300m and the green (532nm) pointer up to 1000m. We would not guarantie that..... see above.

How good is the visability of a laser pointers spot?
Nobody can see light from the side, only the photons which fall into your eye are recognized as "light." What you actually see are particles reflecting the light, i.e. you will see the particles, not the light.

Is a laser pointer dangerous?
Basically: YES. Although all laserpointer for presentation we offer belong to class 2 (Output power equal or less than 1 mW) and are considered to be safe. The safety people felt the brightness of the beam triggers a "lid close effect", i.e. you will close your eye and the time and power is not enough to cause an injury. However, if you stare into such a beam it will damage your retina, be sure! Therefore, a pointer should not be in your kids hands!

A class 3B laser pointer is much more dangerous - not only for your eye, but also for your skin! In your own interest, you should NOT use them. Keep in mind: you have just 2 eyes and a damage of the retina is often found years later, when you discover dark spots in your view field.

American classification allows high power pointer to be classified as class 3A. The same pointer classified in accordance with the European safety standards would belong to class 3B.

Do I need to report the use of a laser pointer?
No. You need to report laser equipment class 3B and up and you do need your own laser safety expert or to join a training class about laser safety. Use of laser class 2 must not be reported and for this class you do not need a safety expert etc. If you look for more specific information, contact your local accident insurance or safety agencies (VGB93).

Why is a green laser pointer so much more expensive than a red one?
Red laser pointer are equipped with a laser diode which emits light with red wavelength and a collimator to improve the beam quality. Unfortunately at this time there are no green diode laser available and the technicians made a little detour: They use an infrared diode emitting at 808 nm. This light goes into a cristal and shifts the wavelength to 1064nm, which still is invisible infrared light. Next the light goes into a second special cristal for frequency doubling to get the wavelength down to 532 nm (green). Now they need to filter our the infrared wavelengths and to improve the quality by a collimator. All these additional parts cost money and must be aligned extremely precise. And that costs ....

How can I determine whether a pointer contains a 650 or a 635 nm diode?
This is not easy. One would need a so called monocromator to determine the wavelength. If you own two pointer and you know one is 650nm and the other one 635nm and both should have the same output power, you may want to try which one appears brighter - that one most likely is the 635nm pointer. But as the output power of a pointer has some tolerance, this is not a guarantie.