WHAT IS LASER ETCHING?

THERE ARE SEVERAL DIFFERENT TYPES OF LASERS, BUT THEY ALL GENERALLY WORK THE SAME WAY. IN ORDER TO UNDERSTAND HOW LASERS WORK, WE MUST ZOOM WAY IN TO THE FUNDAMENTAL BUILDING BLOCKS OF OUR UNIVERSE. WITH ABUUT 100 DIFFERENT TYPES ARRANGED AND BONDEU IN AN UNLIMITED NUMBER OF COMBINATIONS, HIUMS MAKE UP EVERYTHING AROUND US. FROM WATER TO METAL TO THAT FUNNY GAS THE DENTIST GIVES YOU, IT'S ALL BUILT FROM ATOMS.

AN ATOM CONSISTS OF A NUCLEUS WHICH IS MADE UP OF PROTONS AND NEUTRONS WITH AN ELECTRON CLOUD ORBITING THE NUCLEUS. THE ELECTRON CLOUD IS ALWAYS MOVING AND ORBITING THE NUCLEUS, EVEN WITHIN SOLID MATERIALS WHICH SEEMS COUNTERINTUITIVE. THIS MOVEMENT WITHIN THE ATOM CAN ALSO BE DESCRIBED AS THE ENERGY OF THE ATOM. IF MORE ENERGY IS THEN APPLIED TO AN ATOM THOUGH HEAT, LIGHT OR ELECTRICITY IT CAN LEAVE WHAT IS CALLED A GROUND-STATE ENERGY LEVEL AND GO INTO AN EXCITED LEVEL. AS THE ATOM GOES FROM GROUND-STATE TO EXCITED THE ELECTRON CLOUD ORBITING THE NUCLEUS ESSENTIALLY MOVES IT'S ORBIT FURTHER AWAY FROM THE NUCLEUS. IF THE EXTRA ENERGY IS THEN REMOVED AN EXCITED ATOM WANTS TO RETURN TO ITS GROUND-STATE. WHEN THE ATOM DOES RETURN TO GROUND-STATE AND THE ELECTRON OBIT MOVES BACK CLOSER TO THE NUCLEUS, IT RELEASES THAT ENERGY AS A PHOTON OR A PARTICLE OF LIGHT.

THE REASON METAL TURNS A RED WHEN HEATED OR ELECTRIFIED IS BECAUSE THE METAL ATOMS HAVE BEEN EXCITED AND ARE RELEASING RED PHOTONS AS IT RETURNS TO GROUND-STATE. APPLYING ELECTRICITY TO CERTAIN TYPES OF METAL LIKE TUNGSTEN WITHIN A VACUUM GIVES US LIGHTBULBS WHICH THROW SEVERAL DIFFERENT WAVELENGTH LIGHT PHOTONS IN ALL DIRECTIONS. LASERS ARE SIMILAR WITH ALSO USING THE PHOTONS EMITTED FROM EXCITED ATOMS, BUT ARE DISSIMILAR IN THE FOLLOWING WAYS. ONE, THE LIGHT PHOTONS RELEASED ARE MONOCHROMATIC AND ONLY CONTAIN ONE SPECIFIC WAVELENGTH OR COLOR. TWO, THE LIGHT PHOTONS RELEASED ARE COHERENT AND MOVE IN STEP WITH THE OTHERS. THREE, THE LIGHT PHOTONS RELEASED ARE DIRECTIONAL AND MOVE IN A TIGHT BEAM. TO ACHIEVE THESE THREE PROPERTIES, IT TAKES SOMETHING CALLED STIMULATED EMISSION.

STIMULATED EMISSION OCCURS BY PUMPING OR QUICKLY SHOCKING THE LASING MEDIUM WITH LIGHT OR ELECTRICITY.

IT'S THAT CLICKING SOUND YOU HEAR WHEN YOU'RE AROUND A LASER MACHINE. THE PUMP OR SHOCK MUST BE LONG AND STRONG ENDUGH TO EXCITE THE LASING MEDIUM ATOMS TO PRODUCE A POPULATION INVERSION OR IN OTHER WORDS MORE ATOMS IN THE LASING MEDIUM ARE IN EXCITED STATES THAN IN GROUND-STATES. ONCE A POPULATION INVERSION HAS BEEN ACHIEVED AND THE LASING MEDIUM RETURNS BACK TO GROUND-STATE THE EMITTED PHOTONS START A CHAIN REACTION WHERE THEY HIT AND EXCITE THE UNEXCITED ATOMS NEXT TO THEM. THOSE NEWLY EXCITED ATOMS THEN IN TURN EXCITE THE UNEXCITED ATOMS NEXT TO THEM AND THE REACTION MOVES ON. THIS CHAIN REACTION CAUSES THE EMITTED PHOTONS TO ALL HAPPEN IN THE SAME DIRECTION, THE SAME WAVELENGTH AND SAME PHASE.

WHEN THIS ACTION OCCURS IN AN OPTICAL CAVITY OR A LASER TUBE, THE EMITTED PHOTONS ARE BOUNCED BACK AND FORTH FROM END TO END BACK THROUGH THE LASING MEDIUM BY TWO MIRRORS CONTINUING THE REACTION. ONE OF THESE MIRRORS IS ONLY PARTIALLY REFLECTIVE AND LETS SOME OF THE PHOTONS THOUGH WHERE THEY EMERGE FROM THE TUBE AS A LASER BEAM.

LASER ETCHING MACHINES THEN PRECISELY REDIRECT THAT LASER BEAM WITH MIRRORS MOUNTED TO MOVEABLE FRAME RAILS AND A MOVEABLE HEAD UNIT. THE MOTIONS OF THE MACHINE ARE COMPUTER NUMERICAL CONTROLLED (CNC) ALLOWING THE LASER BEAM TO VAPORIZE MANY DIFFERENT MATERIALS IN AN ALMOST UNLIMITED NUMBERS OF DESIGNS, SHAPES, IMAGES, LOGOS, ETC.