LASER TECHNOLOGY

BY: JASIKA, BRIAN.T, SIMRAN, SHANTÉ, TWINKLE, BRIAN.A

WHAT IS LASER TECHNOLOGY?

LASER TECHNOLOGY ARE LASERS THAT PRODUCE AN INTENSE BEAM OF A SPECIFIC WAVELENGTH/COLOUR

THE WORD LASER STANDS FOR LIGHT AMPLIFICATION BY SIMULATED EMISSIONS OF RADIATION

HISTORY

• 1917 – ALBERT EINSTEIN FIRST THEORIZED ABOUT THE PROCESS WHICH MAKES LASERS POSSIBLE, CALLED "STIMULATED EMISSION"

• 1954 – CHARLES TOWNES & ARTHUR SCHAWLOW INVENTED THE MASER (MICROWAVE, AMPLIFICATION, BY STIMULATED EMISSION OF RADIATION) USING AMMONIA GAS & MICROWAVE RADIATIONo THE MASER WAS INVENTED BEFORE THE (OPTICAL) LASER

• DIFFERENT MATERIALS CAN BE USED AS LASERS LIKE THE RUBY LASER, EMIT SHORT PULSES OF LASER LIGHT OR HELIUM-NEON GAS LASERS OR LIQUID DYE LASERS EMITS A CONTINUOUS BEAM OF LIGHT

RUBY LASER –• IN 1960, THEODORE MAIMAN

INVENTED THE RUBY LASER CONSIDERING TO BE THE FIRST SUCCESSFUL OPTICAL OR LIGHT LASER

• MANY HISTORIANS CLAIM THAT THEODORE MAIMAN INVENTED THE FIRST OPTICAL LASER, HOWEVER THERE IS SOME CONTROVERSY THAT GORDON GOULD WAS THE FIRST

GORDON GOULD –• WAS THE FIRST TO USE THE WORD

"LASER"

• GOULD WAS A DOCTORAL STUDENT IN COLUMBIA UNIVERSITY UNDER CHARLES TOWNES, THE INVENTOR OF THE MASER

• HE [GOULD] WAS INSPIRED TO BUILD HIS OPTICAL LASER STARTING IN 1958 UNTIL HE FAILED TO FILE FOR A PATENT

• IT TOOK UNTIL 1977 FOR GORDON TO FINALLY WIN HIS FIRST PATENT FOR THE LASER

HOW A LASER WORKS1. LASERS CONTAIN AN ELECTRIC FLASH TUBE THAT EMITS A SERIES

OF BRIGHT FLASHES OF LIGHT

2. ELECTRONS IN THE ATOMS OF THE RUBY ROD ABSORB PHOTONS FROM THE FLASH TUBE AND MOVE INTO HIGHER ENERGY LEVELS

3. WHEN THESE EXCITED ELECTRONS DROP BACK TO A LOWER ENERGY LEVEL, THEY EMIT PHOTONS WITH A SPECIFIC WAVELENGTH

4. THE RELEASE OF PHOTONS BY A FEW ATOMS TRIGGERS OTHER ATOMS TO DO THE SAME

5. THIS ACTIN INCREASES THE INTENSITY OF THE LASER LIGHT

6. MIRRORS REFLECT THE PHOTONS BACK AND FORTH BETWEEN THE ENDS OF THE RUBY ROD, AND THE LASER BEAM EVENTUALLY PASSES THROUGH THE MIRROR AT THE RIGHT END OF THE ROD

QUANTUM MECHANICS• A PHOTON WITH A CERTAIN AMOUNT OF ENERGY EXCITES AN

ELECTRON TO A HIGHER ENERGY LEVEL

• THE ELECTRON RETURNS TO ITS ORIGINAL ENERGY LEVEL AND RELEASES A PHOTON WITH THE SAME ENERGY

• THE PHOTONS COLLIDE WITH OTHER ATOMS TO RELEASE MORE PHOTONSo THIS IS CALLED THE AMPLIFICATION OF PHOTONS

• THE PHOTONS ALL HAVE THE SAME WAVELENGTH AND TRAVEL IN PARALLEL WAVES ON THE SAME PATH

CLASSIFICATIONS OF LASERS• THERE ARE FOUR DIFFERENT CLASSES OF LASERS IN WHICH THEY

DETERMINE THE POWER OR ENERGY EMITTED FROM THE LASER BEAMS

o CLASS 1 – LASERS THAT ARE SAFE FOR MOST USES

CLASS 1 LASERS ARE CONSIDERED TO BE INCAPABLE OF PRODUCING DAMAGING RADIATION LEVELS, & ARE THEREFORE EXEMPT FROM MOST CONTROL MEASURES OF OTHER FORMS. NO INDIVIDUAL, REGARDLESS OF EXPOSURE CONDITIONS TO THE EYES OR SKIN, WOULD BE EXPECTED TO BE INJURY BY A CLASS 1 LASER

o EXAMPLES: LASER LIGHTS, SOME PRINTERS AND DISC PLAYERS

CLASSIFICATIONS OF LASERS CONT.

o CLASS 2 – LASERS EMIT RADIATION IN THE VISIBLE PORTION OF THE SPECTRUM, & PROTECTION IS NORMALLY AFFORDED BY THE NORMAL HUMAN AVERSION RESPONSE (BLINK REFLEX) TO BRIGHT RADIANT SOURCES

o THEY MAY BE HAZARDOUS IF VIEWED DIRECTLY FOR EXTENDED PERIODS OF TIME

o EXAMPLES: LASER POINTERS, AIMING DEVICES AND RANGE FINDING EQUIPMENT

CLASSIFICATIONS OF LASERS CONT.

o CLASS 3 – ARE LOW POWER (<MW – MILLIWATTS), VISIBLE LIGHT LASERS

2 TYPES:

• CLASS 3A – ARE CONTINUOUS WAVE, INTERMEDIATE POWER (1-5 MW) DEVICESo EXAMPLES: LASER POINTERS & LASER SCANNERS

• CLASS 3B – ARE INTERMEDIATE POWER (5-500 MW) DEVICES. DIRECT VIEWING OF THE CLASS 3B LASER BEAM IS HAZARDOUS TO THE EYE AND DIFFUSE REFLECTIONS OF THE BEAM CAN ALSO BE HAZARDOUS TO THE EYEo EXAMPLES: SPECTROMETRY, STEREO LITHOGRAPHY & ENTERTAINMENT LIGHT

SHOWS

CLASSIFICATIONS OF LASERS CONT.

o CLASS 4 – ARE HIGH POWER (>500 MW) DEVICES. THE DIRECT BEAM AND DIFFUSE REFLECTIONS FROM CLASS 4 LASERS ARE HAZARDOUS TO THE EYES & SKIN

o EXAMPLES: SURGERY, RESEARCH, DRILLING, CUTTING, WELDING & MICRO-MACHINING

• CLASS 4 LASERS RANGE FROM MEDICAL LASERS USED TO REMOVE HAIR, BLEMISHES AND SCARS TO POWERFUL INDUSTRIAL LASERS USED TO CUT THROUGH METALS OR STACKS OF FABRIC IN THE MANUFACTURE OF GARMENTS

• VERY DANGEROUS AND REQUIRE SAFEGUARDS