Laser Eye Effects (1968) / Chapter Skim
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A Review of Technical Characteristics of Lasers
A Review of Technical Characteristics of Lasers
Pages 4-19
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From page 4... ...
in length with peak powers of the order of 10 to 1000 megawatts and pulse energies, typically, from 0.1 to 10 joules. Alternatively, the same lasers operated in the normal or "long-pulse" mode generate pulses on the order of a millisecond in length, peak powers up to hundreds of kilowatts, and pulse energies from a few joules to a few kilojoules.
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From page 5... ...
High-efficiency frequency doubling or even quadrupling is a practical method for obtaining radiation of shorter wave lengths. Further, many lasers can be operated in the multimode phase-locked condition, which causes the output to consist of sharp, regular spikes whose peak power may be orders of magnitude larger than the average power.
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From page 6... ...
Frequency doubling, and even quadrupling, from 1060 mjj (nd'+ in yttrium-aluminum-garnet) or other infrared lasers may be a practical means for providing visible coherent sources at other wavelengths if direct lasing action throughout the visible remains difficult to achieve.
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From page 7... ...
Neodymium (3+) Host Lattice Ma t e r i a 1 Yttrium oxide plastic chelate in alcohol Alumi num oxi de Fluorides of calcium and strontium Glass Calcium tungstate Vari ous fluori des, molybdates, glass Principal Output Wavelength .bl p .70 p .71 p 1.02 p 1.05 p I.0b u Thu 1 i urn (2+)
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From page 8... ...
Table 2 Principal Gases Known to Exhibit Laser Action Gas Emission Di stri but ion Emission Frequency Range Argon 86 (strong 1 i nes 1 i nes from 35H-5145A) 2753A 26.95 u Bromi ne k 1 ines regi on of 8446 A Carbon 9 1 i nes kbkj A - 5.5956 u Ces i um 2 1 ines 3.204 u and 8.1821 p Chlorine 11 1 i nes 4781 A - 2.2060 u He 1 i um 2 1 ines 1 .9543 u and 2.0603 /J lodi ne 8 1 i nes 5407.4 A - 3.431 H Krypton 59 1 i nes 3050A 7.0565 y Mercury 25 1 i nes 4797 A - 1.813 v Neon 155 lines (line at 3.39 u has gain 40dB/meter)
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From page 9... ...
-- With the exception of cesium vapor, all are stimulated by passage of an electrical current.
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From page 10... ...
Table 3 Principal Diode Materials Currently in use in Semiconductor Lasers Laser D i ode Mater ia 1 Gal 1i urn arsenide Indi urn phosphide Indi um arseni de Gallium indium-arsenide Indi um antimoni de Gallium arsenide-phosphide Em i s s i on F requency Range 0.840 p - 0.932 p 0.900 ^i - 0.919 M 3.112 u 0.840 p - 3.100 y 5.200 y 0.610 - 0.840 Note. -- Efficiency of operation is high approaching 40%; however, total power density that can be achieved is low.
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From page 11... ...
Multiple-layer dielectric coatings can be produced with losses as low as a few tenths of a percent, so that even low gain transitions can be made to oscillate. Although flat mirrors are still used in most solid state lasers, concave spherical reflectors are more common in gas lasers since the tilt of the mirrors does not have to be adjusted as accurately.
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From page 12... ...
However, most lasers have many modes present, and the total frequency spread is primarily determined by the width of the fluorescent line of the active material, as discussed briefly in the previous section. Except for nd-glass, the linewidths of most of the common lasers are still very narrow even when oscillating multimode.
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From page 13... ...
In these crystals, the terminal laser level is above that of the ground state far enough so that it is normally nearly empty at the operating temperature of the laser, thus reducing pumping power requirements. In addition, the pump bands absorbed by neodymium are much wider than for most similar crystals and pumping can also be accomplished to several upper energy states rather than one or two narrow bands as is the case with ruby.
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From page 14... ...
The strongest visible laser line from the helium-neon mixture is at 633 ">«• Recently, considerable work has been done using carbon dioxide and nitrogen, and also ionized rare gas lasers. Relatively high powers have been achieved from these devices with outputs reported in the 20 watt range for ionized argon and over 1,000 watts for carbon dioxide.
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From page 15... ...
While other gases have been used in place of carbon dioxide, i.e., nitrous oxide, carbon monoxide, and carbon disulfide, highest power outputs have been achieved using the former. SEMIC0NDUCT0R LASERS In November 1962, successful laser action was first achieved in the junction region of a gallium arsenide semiconductor diode^.
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From page 16... ...
While it is difficult to achieve an accurately reproducible wavelength, diode lasers have the advantages of compactness, simplicity, increased efficiency of operation, a power output that may be adjusted and quickly controlled by simply changing the electrical input into the diode. SPECIAL SYSTEMS Gaint pulse laser Using special techniques it is possible to achieve enormously high peak powers in very short pulses.
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From page 17... ...
Discovery of the stimulated Raman effect using laser beams has made available many new wavelengths of high intensity coherent light. Harmonic generation Because of the intense power density which can be obtained in focused laser beams, and in particular with giant pulse lasers, it is possible to generate appreciable harmonic power in many materials.
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From page 18... ...
-5136. Submitted to Air Force Missile Development Center, Air Force Systems Command of the United States Air Force, Parts I and II (1965)
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From page 19... ...
H Glew, Biological Effects of Laser Radiation, Washington, D
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