Saturday, April 5, 2014

New Gear: Tripod Weight and Green Laser Pointer

Ok so my tripod weight isn't NEW, but it is new to this application. I haven't been using anything on the little weight hook on my tripod, so I tied this cheap plastic dumbbell weight to a string and hung it up. It not only adds weight to the overall tripod (decreasing wobble in the wind) but also lowers the center of mass so the tripod is less likely to topple over if bumped.

attach weight to tripod
2.5 lb weight on twine hanging from the tripod as low to the ground as possible

attach weight to tripod
A simple loop of string for this 2.5 lb weight

add weight to tripod

weight on tripod
On flat ground, the weight hangs just above the grass

Next up, I was super pumped when this green laser pointer arrived as a late Christmas present. I should point out, that at 100mW this green (532nm wavelength) laser is far too strong to be sold as a "laser pointer" - in fact, anything above 5mW in the United States cannot be marketed as a "pointer" by FDA regulations.

laser pointer with safety label

However, the safety label on the laser does say that the max output is <100mW, that it's a class III laser product, and that it complies with 21CFR (what the heck is that?). So I looked it up:
21 CFR 1040.11(b) and 1040.11(c), limit surveying, leveling, and alignment, and demonstration laser products to Class IIIa. This means that pointers are limited to 5 milliwatts output power in the visible wavelength range from 400 to 710 nanometers. There are also limits for any invisible wavelengths and for short pulses. Pointers may not exceed the accessible emission limits of CDRH Class IIIa or IEC1 Class 3R. (
Well now I'm confused. The laser was marketed as 100mW but the label says <100mW. It says it complies with 21CFR, but the laser also includes the words "laser pointer" on the metal clip. It states that it is Class III but not whether it is IIIa or IIIb. So which is it?

laser pointer label
Is this label illegal for a "pointer" stronger than 5mW?

Either way, this is a potentially dangerous laser product that is capable of lighting a match from 30 cm range, blinding pilots, and causing all kinds of legal problems with the FAA. Let's just say I plan to use it sparingly to point out constellations. I've also read some good tips online, such as always keeping the laser moving and circling stars rather than pointing right at them just in case they are aircraft.

green laser pointer

You might also check out this article from Universe Today on the Hazards of Green Laser Pointers, and Some Pointers on the Use of Laser Pointers from Sky & Telescope. Also, I'm not sure if it's the law here, but the Astronomical Society of South Australia recommends carrying your astronomical society membership card with you to show authorities that you are using your laser for educational purposes.

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