Lasers

I always liked lasers. Ever since I since I first saw an Austin Powers movie, I had always wanted “sharks with frikin’ laser beams attached to their foreheads”. Apparently, that was not too much to frikin’ ask, as my friend was kind enough to photo-shop me a picture of one. But I digress.

            How a laser works (in classical theory) is a more serious matter entirely. The general principle is to get a collection of atoms and give them enough energy to get them to an “excited” state. Once the atoms are excited, the atoms will eventually lose energy and emit a photon. Upon a photon being emitted, other atoms follow suit and emit other photons because atoms want to be like other atoms. These photons are in exactly the same phase, and exactly the same wavelength. This phenomenon, results in the coherent, collimated beam. Instead of allowing all the photons to escape, a laser is constructed in such a way as to have all the photons bounce back and forth between mirrors, generating even more photons; and as long as the active gain medium has energy it’ll keep on generating photons forever. Once all the photons are bouncing between the two mirrors, a slight gap in between them is opened up, generally done naturally with a 99% reflective mirror, and the result is a coherent, collimated beam of light. A laser beam.

            Mathematically speaking, a laser operates on the principles described above, resulting in the equation ΔE=hν. E in this equation is the difference in energy of the atoms, h is plank’s constant, and ν is the frequency of the photon. This equation was derived from Einstein’s insights on the Photoelectric Effect (which we can talk about later), which won him the Nobel Prize in 1921.

            The really cool thing though is with minor differences to the construction, (such as the original collection of atoms, or the energy supply) lasers range from a bar-code scanner to a mighty weapon of fiery death, or something that is actually practical in our lives.