LASER LIGHT

LASER LIGHT IS MUCH MORE INTENSE, DIRECTIONAL, MONOCHROMATIC AND COHERENT THAN NORMAL LIGHT. THE WAVES OF LASER LIGHT ARE COORDINATED IN SPACE AND TIME AND HAVE NEARLY THE SAME LENGTH. THIS COHERENCE AND CHROMATIC PURITY, AND ALSO THE INTENSITY OF LASER LIGHT, RESULTS FROM THE FACT THAT IN A LASER EXCITED ATOMS ARE SIMULATED TO RADIATE LIGHT COOPERATIVELY BEFORE THEY HAVE HAD TIME TO DO SO SPONTANEOUSLY AND INDEPENDENTLY. THE DIRECTIONALITY OF LASER LIGHT ARISES FROM THE GEOMETRY OF THE LASER. LASER LIGHT IS NOW AVAILABLE IN A LARGE NUMBER OF WAVE-LENGTHS, RANGING FROM THE ULTRA VIOLET REGION TO THE FAR-INFRARED REGION OF THE ELECTROMAGNETIC SPECTRUM. MOST LASERS CONSIST OF A COLUMN OF ACTIVE MATERIAL THAT HAS A PARTLY REFLECTING MIRROR AT ONE END AND A FULLY REFLECTING MIRROR AT THE OTHER. LIGHT INTENSITIES AS HIGH AS A BILLION WATTS PER SQUARE CENTIMETER HAVE BEEN PRODUCED. A SCHEMATIC DRAWING ILLUSTRATES THE TECHNIQUE USED TO RECORD PICO-SECOND LASER PULSES. ONE OF THE INTERESTING APPLICATIONS OF THE LASER IS THE PROBING OF MATERIALS BY THE STUDY OF THEIR BRILLOUIN SCATTERING OF LIGHT. THE FORMULA FOR BRILLOUIN SCATTERING MAKES IT POSSIBLE TO MEASURE THE VELOCITY OF SOUND AT VARIOUS WAVE-LENGTHS IN ANY LIQUID AND THUS TO STUDY IMPORTANT PROPERTIES OF MATERIALS. THE LASER IS BEING APPLIED TO PROBE THE INTERNAL STRUCTURE AND BEHAVIOUR OF MOLECULES, BY EXAMINING THE LIGHT-SCATTERING PHENOMENON KNOWN AS THE RAMAN EFFECT. THE POWER PER INTERVAL OF WAVE- LENGTH OF THE LASER IS MUCH GREATER THAN FROM OTHER SOURCES SIMPLY BECAUSE OF ITS GREATER MONOCHROMATICITY. THE HIGH COHERENCE OF LASER LIGHT PERMITS FOCUSING TO A SINGLE POINT WITH A STARTLING INCREASE OVER ANY OTHER OPTICAL SOURCE IN POWER PER SQUARE METER WITHIN THE FOCUSED SPOT. THE ONLY KNOWN CONTINUOUS LASER THAT IS CAPABLE OF A LARGE POWER OUTPUT IS THE CARBON DIOXIDE TYPE. INVESTIGATORS ARE NOW WORKING ON THE DEVELOPMENT OF COHERENT LIGHT SOURCES THAT ARE TUNABLE. A PARAMETRIC OSCILLATOR IN THE VISIBLE RANGE THAT PRODUCES TUNABLE BEAMS AT A POWER OF HALF A MILLIWATT HAS BEEN CONSTRUCTED. IT SEEMS LIKELY THAT PICOSECOND LASER PULSES WILL BE HIGHLY USEFUL IN EXPLORING THE INTERIOR OF ATOMS. THE DEVELOPMENT OF VISIBLE-LIGHT LASERS IS PROVIDING EXCITEMENT.

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  • Supplemental Notes:
    • Vol 219, No 3, PP 120-136, 5 FIG, 2 PHOT
  • Authors:
    • Schawlow, A L
  • Publication Date: 1968-9

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  • Accession Number: 00242905
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Nov 4 1994 12:00AM