Lasers Invention to Application (1987) / Chapter Skim
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Lasers in Modern Industries
Lasers in Modern Industries
Pages 17-44
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From page 17... ...
The ammonia beam maser was the first device to use stimulated emission from inverted-population states of quantum mechanical resonances to provide gain for an electromagnetic oscillator. The operation of this quantum mechanical device initiated the field of quantum electronics.
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From page 18... ...
The laser made it possible to transport into the optical region all the basic techniques developed for application in the radio and microwave regions, such as harmonic generation; parametric amplification; amplitude, frequency, and phase modulation; homodyne and heterodyne detection; and chirping and pulse compression. In the 25 years since the laser was first realized in the form of pulsed coherent emission from a single ruby crystal, the field has grown at a rate rarely experienced in science.
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From page 19... ...
MA NUFA CTURING TECHNOl OG Y PHASE Laser technology has now definitively entered the manufacturing technology phase. Sizable markets have been identified.
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From page 20... ...
In contrast to earlier phases, the commercial and industrial markets are now larger than the military market. Consumers are also beginning to experience laser technology directly through video and audio discs, laser printers for small computers, bar code readers at checkout counters, fiber-optic telecommunications, and various medical treatments.
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From page 21... ...
....... TOTAL MARKET 1984 -- $4,160 M ~3 1983 -- $3,215 M I 1 1 1 1 1 1 0 400 800 1,200 1,600 2,000 2,400 2,800 DOLLARS x MILLIONS FIGURE l Laser industry world markets.
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From page 22... ...
//////////////////////////,/////////A //////////, ~ ,////, 40 50 increase in this period, and the commercial market grew by a phenomenally large 44 percent. COMMERCIAL LASER INDUSTRY A more detailed look at the 1983 and 1984 commercial laser world market reveals that approximately 63 and 50 percent, respectively, of these 2 years' commercial markets ($1.25 billion and $1.44 billion, respectively)
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From page 23... ...
3 it ...... , war TOTAL 1984 -- $2,855 M 1983 -- $1,985 M 1 1 1 1 1 1 1 0 200 400 600 800 1,000 1,200 1,400 DOLLARS x MILLIONS FIGURE 3 Commercial laser industry world market.
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From page 24... ...
One or both of i//////////// ///////////////////////~ ////////////////////~ ///////////////////~//~ /////////////////////~ /////// a//// ////////////////////~ 1 1 1 1 1 1 0 10 20 30 40 50 60 % GROWTH FIGURE 4 Commercial laser industry growth, 1983-1984.
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From page 25... ...
Much of the laser communications market that is, the fiber optics telecommunications market—is held by large, vertically integrated corporations such as AT&T, ITT, and Nippon Telegraph & Telephone and is thus not available to other manufacturers. Undoubtedly, this accounts for the relatively small fraction of the total world market of the commercial laser industry attributable to the laser communications market, as shown in Figure 3.
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From page 26... ...
This development has spawned many new sectors of major industries, such as telecommunications, printing, video and audio discs, data recording, and bar code reading (Figure 61. In another example of the large markets generated by semiconductor lasers, Frost & Sullivan, Inc.
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From page 27... ...
The success of the semiconductor diode laser in bringing about many new sectors of major industries is probably attributable to its compatibility with semiconductor integrated circuits. Its small size, low manufacturing cost, low voltage and power requirements, and high efficiency make it compatible with modern electronic technology.
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From page 28... ...
At present, the technologies of integrated optics and guided wave optics are being developed by researchers whose goal is to obtain benefits in the optical region similar to those obtained earlier in the electronic region by planar electronic integrated circuits, hybrid circuits, and planar microwave/millimeter strip-line technologies. The ability to realize both optical and electronic devices from compound semiconductor technology is largely responsible for the present intensive research on compound semiconductors.
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From page 29... ...
As photonics continues its rapid expansion past its 25th birthday, it is also expanding the future horizons of electronics technology. Since the 1912 invention of the electronic oscillator, there has been a steady drive toward the production and use of coherent electromagnetic energy of higher and higher frequencies.
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From page 30... ...
This realization led to the invention of the ammonia beam maser and the laser and to the creation of the field of photonics. This section will briefly discuss selected applications of lasers in semiconductor integrated circuits manufacturing, radar systems.
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From page 31... ...
The laser system is then used to open the polysilicon conductor, shorting out the spare address encoder and thereby connecting that encoder to the other circuitry of the chip. Figure 7a shows a small portion of an integrated circuit, including functioning polysilicon film conductor interconnecting lines, crystal silicon substrate, silicon dioxide insulator film, and aluminum film interconnecting lines.
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From page 32... ...
, the silicon dioxide insulator film (B ) , the aluminum film Interconnecting conductor lines (C)
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From page 33... ...
The utility of the laser in these applications can be seen by referring to the Stefan-Boltzmann law of radiation: The total energy radiated per unit area by a perfect thermal source is equal to the fourth power of the temperature times the Stefan-Boltzmann radiation constant. For instance, a power density of 1 million W/cm2 corresponds to a thermal source operating at 20,500 K
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From page 34... ...
For a laser beam moving continuously across a material, the interaction time can be defined as the time required for the incident laser spot to move one diameter relative to the surface of the workpiece. For a material process requiring short pulses of laser radiation, the interaction time is the duration of the pulse, since the material can be assumed to be stationary during the short irradiation process.
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From page 35... ...
This type of radar was originally used extensively in the early development of radar technology to detect moving targets against stationary background clutter. Coherent radar systems measure the Doppler shift of the echo radiation by comparing the frequency of the received echo signal with the frequency of the transmitted radiation.
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From page 36... ...
Since the beam divergence varies directly with wavelength and indirectly with transmitting aperture, CO2 laser radars have 3,000 times smaller beam divergence than x-band radars with the same aperture. Since the Doppler shift varies inversely with wavelength, the CO2 laser radar has three orders of magnitude higher Doppler sensitivity than an x-band radar (see Figure 1 1~.
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From page 37... ...
1 10-1 10-2 co ID ~ 10 ~7 10 10-5 10-6 10-7 300 MHz / / /~-0, // . ~/~ / CO2; f ~ 3 x 1 o1 3~ 2/V/~// -2 1o~1 1 10 1o2 103 10 2 x velocity -- km/hr ~ RF Microwaves Millimeter waves 1 Infrared Tvisible luv FIGURE l l Comparison of Doppler sensitivity: Doppler frequency shift as a function of radar wavelength and target velocity.
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From page 38... ...
Fortunately, the operating wavelengths of CO2 lasers falls within one of the best atmospheric windows when compared with other laser wavelengths. Consequently, for applications in the atmosphere, the relatively long wavelength of 10.6 ,um for CO2 lasers over other lasers, such as Nd3+:YAG, ruby, and semiconductor lasers, makes the CO2 laser radar the system of choice for most applications.
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From page 39... ...
The trees in the far background were not recorded in the radar image because of range-gating techniques used in the radar system. Range: 1,200 m; average power: i/ W; pulse rate: 30,000/s.
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From page 40... ...
A central conductor of stranded copper wire passes through an extruder that coats it with a smooth, thin semiconducting shield consisting of PE filled with carbon black. Over this opaque semiconducting surface, the white PE insulation is extruded and then crosslinked with heat, ultraviolet radiation, or electron bombardment.
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From page 41... ...
These irregularities are caused by gas- or vapor-filled voids, contaminating particles, inhomogeneous variation of density in the materials, and other defects. Unfortunately, visual inspection is not possible during the manufacturing process, where these defects arise, because PE is normally a milky white, opaque material except when immersed in hot oil.
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From page 42... ...
Figure 16 shows an experimental arrangement of such a system. It is important to note that because of the long laser wavelength (submillimeter wavelengths)
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From page 43... ...
It is now spawning new products and opening major new segments of basic industries that will ensure its growth well into the next century. The fields of fiber-optic telecommunications, optical audio and video discs, optical data storage, optoelectronics, lasers for material working (cutting, welding, heat treating, hole drilling, and scribing)
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From page 44... ...
The most serious challenge in laser technology is the continuing shortage of photonic engineers required to develop the numerous new and rapidly evolving products the technology is generating, to continually advance the state of the art required to meet new product needs, and to work at the interface between electronics and photonics technologies. An engineer in this field needs a background in optics and electronics and in quantum electronics.
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