I am flying from the UK to the US for a short house hunting trip. I want to bring a laser range finder in my carry-on luggage. It is a class 2 laser so should be considered safe, but you never know with airport security. Since it is a short trip, I will not have any checked baggage. Are there any TSA guidelines regarding lasers?
Lasers at UK Airports
Lasers aren't mentioned on the governmental webpage on hand luggage restriction at UK airports. Moreover there is no mention of lasers in neither the prohibited items list, nor the guide to dangerous goods, both by British Airways (in PDF). It would therefore seem that they are indeed allowed inside carry-on luggage when departing from UK airports.
Lasers at US Airports
Regarding US regulations, it would seem that according to the TSA, lasers are allowed both in carry-on as well as hold luggage. The TSA prohibited item search tool for
laser (note you'll have to re-run the search to see the results) says:
You may transport this item in carry-on baggage or in checked baggage. For items you wish to carry-on, you should check with the airline to ensure that the item will fit in the overhead bin or underneath the seat of the airplane.
They also add some generic all-purpose advice, which might be relevant in this particular case:
Even if an item is generally permitted, it may be subject to additional screening or not allowed through the checkpoint if it triggers an alarm during the screening process, appears to have been tampered with, or poses other security concerns. The final decision rests with TSA on whether to allow any items on the plane.
I'm not sure how well this carries over, but I've brought my presentation laser pointers many times on planes, and TSA doesn't bat an eye. They stop me for things like a box of pencils (looked like an ammo box) and water bottles (chemicals) and so on.
(Don't get me wrong, I'm grateful for all they do and I don't mind the longer lines and security checkpoints because I'd rather be safe. It just amuses me sometimes what they stop me for vs. what they let me carry through.)