Here are answers to your laser questions.
1. Can you cut trees with lasers?
No. The power requirements would be greater than any current industrial
laser can produce. This is not because the tree is resistant to laser light
it is because of the thickness of the tree. Also there would be laser safety
issues that would have to be addressed.
2. Is there laser proof material?
Yes and no. Good old fashion drywall will stop a pretty powerful beam.
There are companies that make laser barrier material that can stop a beam.
If a laser beam has an optical power in the Megawatt or higher range it
becomes harder to find material that can stop the beam without the material
catching on fire or being blasted away.
3. Does the military have lasers that can destroy a missile?
Yes! The air force has the Airborne Laser System or ABL that was designed to
shoot down an incoming ballistic missile. The testing conducted so far has
proven to be an effective way to shoot down an intercontinental ballistic
4. Flash Photolysis?
Flash Photolysis is a pump-probe technique, in which a laser of nanosecond,
picosecond, or femtosecond pulse width is excited by a short-pulse light
source such as a flash lamp.
I hope this answers your questions.
Laser Institute of America