Harnessing Light Optical Science and Engineering for the 21st Century (1998) / Chapter Skim
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3 Optical Sensing, Lighting, and Energy
3 Optical Sensing, Lighting, and Energy
Pages 125-168
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From page 125... ...
For example, a broad range of newly developed optical sensors and instruments are already used in everyday life, such as those that provide satellite pictures of clouds and weather patterns on TV even i ng news, i nfrared n ight vision scopes used by law enforcement, spaceborne probes to Jupiter that use optical instruments to measure and image the surface temperature of the planet, home security infrared motion sensors, and optical or laser probes to detect and display gas emissions from automobile highway traffic. Related to these advances in optical sensing and imaging technology are associated advances in the development of new, high-efficiency C h a p t e r 3 125
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From page 126... ...
energy consumption by tens of billions of dollars per year, and new laserbased nuclear fusion power plants and mass-produced photovoltaic solar cells are being studied for long-range potential as cheap power in the next century. This chapter presents a synopsis of recent advances in optical sensing instruments and techniques, lighting, and energy.
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From page 127... ...
The use of optical sensors and imaging systems has been enhanced recently with the advent of small, inexpensive video cameras and detectors that operate in both the visible and the infrared; the development of new compact tunable laser sources; and the manufacture of compact C h a p t e r 3 127
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From page 128... ...
The following sections outline the current use and projected growth of optical sensors in environmental and atmospheric monitoring; Earth and global surface monitoring; astronomy and planetary probes; industrial chemical sensors; imaging detectors and video cameras; law enforcement and security; and common everyday optical sensors, printers, and scanners. Environmental and Atmospheric Monitoring Optical systems can be used for the detection of a number of important gases or pollutants in the atmosphere.
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From page 129... ...
Conventional analytical chemical sensors are still dominant, but optical methods now claim about 40% of the market and this fraction is rapidly growing. The current annual U.S.
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From page 130... ...
has been used for more than 25 years to detect from afar a wide range of atmospheric or environmental characteristics, such as temperature, gas concentration, and wind velocity. Lidar uses a laser beam to probe a remote target, aerosol layers, or gas clouds at ranges from 10 m to several kilometers and deduces the range and composition of the cloud or target from the detection of backscattered light.
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From page 131... ...
The current annual world market for this application is on the order of $1 0 million to $40 million. Laser devices have the advantage over radar that the small laser beam can select a single automobile from a group of vehicles and can measure the range to the vehicle with an accuracy of better than a few centimeters.
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From page 132... ...
The market for such optical instruments was about $400 mil lion in 1 991 and is growing rapidly. Future markets are predicted to be about $1 billion annually for monitoring and bioremediation (mak ing harmless)
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From page 133... ...
Earth and Global Surface Monitoring Optical sensors and television imaging systems based on highaltitude aircraft, balloons, and satellites have been used for more than three decades to detect and map weather patterns, mineral resources, ocean currents, and land topography on Earth's surface. Recently, more sophisticated optical instruments have been used that can detect the concentration of important greenhouse gases related to the study of global climate change.
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From page 134... ...
For example, satellite-based multiwavelength optical imaging sensors have been used to map Earth's green biomass, i.e., plant density. An estimated $28 billion has been invested in remote sensing satellites that include optical imaging systems (see Figure 3.5~.
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From page 135... ...
dollars, represents the actual optical components and instruments used in the satellites. There are currently five operational optical imaging satellites in orbit: SPOT 3, Lansat 5, JERS-1, OFEQ 3, and IRS-2C.
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From page 136... ...
techniques that compensate for optical distortions of Earth's atmosphere using "adaptive optics" and laser-excited artificial guide stars in the upper atmosphere; (3) coherent addition of two or more separate interferometric images from separate telescopes to increase the resultant resolution; and (4)
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From page 137... ...
A related experiment at the 1.5-m Starfire Optical Range telescope at Kirtland Air Force Base, New Mexico, uses a yellow laser guide star C h a p t e r 3 FIGURE 3.6 Telescope images with and without an atmospheric compensation adaptive optics system. The large, blurred patch at left is the star tau Cygni as seen without adaptive optics.
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From page 138... ...
Finally, either groundbased or space-station-based imaging sensors will be used to detect debris in low Earth orbit. Planetary and Space Probes Unique optical instruments have been used for several decades for planetary, astrophysics, and Earth remote sensing from orbital and interplanetary platforms, including the detection and measurement of the temperature and atmospheric composition of planets (Venus, Mars, Jupiter)
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From page 139... ...
Among recent technological advances that wi 11 enable new space science are ambient temperature IR detector materials for the spectral range from 2 to 5 ~m, agile spectroscopic optical filters, lens optimization modeling, and integrated optics spectrometers. These particular developments are examples within an extensive optics program technology structure that can be categorized into several generic components: optical testi ng, wavefront sensing and control, and spectroscopic sensor optical systems.
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From page 140... ...
market for optical chemical sensors is several hundred million dollars. It represents a niche market at present but is growing rapidly.
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From page 141... ...
Such metrological sensors are covered in more depth and breadth in Chapter 5. Digital, Video, and Thermal Imaging Cameras Video or television cameras have been in use for more than 50 years, but they have become household items only within the past 15 years as a result of the development of new, compact silicon semiconductor C h a p t e r 3 FIGURE3.8 Recentgrowth in demand for atomic spectroscopic optical instrumentation.
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From page 142... ...
in these video cameras is usually about 500 x 500 at present. A new, rapidly growing segment of imaging detectors is the development of digital cameras that use CCD detectors instead of photographic film.
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From page 143... ...
Examination of physical evidence is usually done with the ubiquitous microscopes and standard laboratory analytical chemical techniques. As in the case of industrial chemical sensors, a significant amount of new research is being conducted in the potential use of optical sensors in law enforcement, with a large fraction of new applications using newly developed sensor technology from DOD.
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From page 144... ...
Several DOD agencies have recently started laser and optics application groups directed toward the application of new optical sensor technology for law enforcement and security. The programs include, for instance, the use of an invisible infrared searchlight and camera 1 1 H A R N E S S I N G L I G H T 144
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From page 145... ...
visible lasers that can illuminate a criminal at night to indicate his impending apprehension and helicopter-borne 1 0-W IR laser "spotlights" coupled to a night vision scope and telescope, which have been shown to double search capability. The common household motion sensor used in home security alarms employs infrared detectors that sense the movement of a warm body against the colder background of the room.
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From page 146... ...
Forensics and Evidence Examination The use of optical techniques in forensics and law enforcement for the examination of physical evidence is growing but is still not an accepted practice in general, except for optical microscopy, photography or video, and more recently, DNA analysis. In general, optical sensors are not used in forensics, because they cost too much, they are not portable enough to be taken easily to a crime scene, or other more established techniques are already being used.
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From page 147... ...
Examples include optical bar-code readers, garage and elevator door safety sensors, television remote controls, "ear" infrared thermometers, night-activated photoelectric light switches, infrared coupl ing of personal computers to keyboards and printers, and infrared switches that automatically turn on and off the water faucets in public restrooms. Bar-code readers use either an invisible infrared optical beam or a red, low-power helium-neon laser (supermarket scanner)
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From page 148... ...
There have been steady efficiency improvements as a result of better fluorescent lamps, better reflective and radiative coatings in incandescent bulbs, and new concepts such as light-emitting diodes. This section presents some of the new and exciting advances that are being made in lighting sources and distribution technologies.
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From page 149... ...
Simi larly, low-voltage fluorescent lamps were invented by Meyer in 1926, followed by their commercial production in 1938 by the General Electric Company. Since that time, several other light sources have been invented and used, such as the mercury vapor, metal halide, high-pressure sodium, and halogen lamps, and most recently the sulfur-dimer (microwave discharge)
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From page 150... ...
. New Lighting Sources anti Distribution Systems New lighting sources and distribution systems are being actively studied, with considerable work being done on making existing light sources more efficient, developing new kinds of light sources, and developing new distribution or high-efficiency transmission systems.
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From page 151... ...
Lamps One of the more promising new light sources at present is the sulfr~r-dimer (S2) lamp that mimics the color snectrr~m of sr~nli~ht any r~s , .
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From page 152... ...
LED Lighting Light-emitting diodes are a relatively new (past few decades) light source produced by semiconductor manufacturing techniques; they are used for displays in a wide range of consumer electronics.
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From page 153... ...
The city of Philadelphia has started to replace all red traffic lights over the past 4 years and expects to save several million dollars per year in electrical costs as well as significantly reduced replacement costs. In addition, China and many other developing countries are starting to use LEDs in traffic lights and related signs because their use will reduce the need to build new electrical generating plants in the future.
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From page 154... ...
The use of optics and lasers in live entertainment is stable, with significant growth not expected at present. It should be added that eye safety is always a concern for laser light shows and is often handled by making sure that the laser beams are directed above and away from people in the audience.
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From page 155... ...
Other potential uses for optical instruments include Doppler laser radar to detect wind shear in front of landing aircraft or wake vortices at airports. At present, most commercial aircraft are planning to use Doppler microwave radar for wind shear detection, based on recent fl ight tests by NASA and the Federal Aviation Admin istration (FAA)
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From page 156... ...
Today optics is used extensively in automobiles, and its use is growing as cheaper, more compact light sources and optical devices become available. Traditional lighting applications still dominate, such as headlamps, taillamps, and instrument displays.
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From page 157... ...
Sensors embedded in highways can count and weigh passing vehicles while they are in motion to help in traffic planning and to enforce laws that restrict truck weights. A system based on Bragg gratings has been developed that permits as many as 64 strain gauges to be put on a single optical fiber.
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From page 158... ...
From 1995 to 1998, the United States will also invest about $170 million in this project for the development of laser technology, largescale precision optical components, and low-cost advanced optics manufacturing methods. NIF will be the largest optical system in the world and will develop and employ state-of-the-art adaptive optics systems on each of its 192 laser beam lines.
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From page 159... ...
, to be used for lasercontrolledfusion. The system will have 192 laser beams and will be the world's largest laser and opticalsystem.
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From page 160... ...
The AVLIS project may become the largest technology transfer effort from DOE to the commercial sector. Space Solar Cells Solar cells, which convert light to electricity, have been used as the primary power in communication, defense, and weather satel I ites for the past 35 years and can be considered part of the satellite and spacecraft manufacturing industry.
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From page 161... ...
energy needs. Solar energy, particularly photovoltaic solar cells, could play a central role in renewable energy, especially for electric power generation.
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From page 162... ...
By spreading conversion over 30 years, which is also the approximate lifetime of a panel, the cost would be $150 billion per year. The United States currently spends approximately $200 billion a year on electrical energy; this is about 3% of the $7 trillion GDP per year.
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From page 163... ...
The use of silicon by the solar cell industry is approaching 10% of its use by the electronics industry. There have recently been shortages of silicon for solar cells.
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From page 164... ...
Industrial optical chemical sensors are just starting to be used for process control and have shown significant potential i n several cases. Optical methods are used in only a minority of chemical sensors, but the fraction is growing as sensors and lasers become smaller and cheaper.
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From page 165... ...
Sophisticated optical and laser sensors are not used to a large degree in forensics and law enforcement because of their cost and lack of portability, but video surveillance and infrared motion security sensors are used extensively. Infrared LED and laser spotlights coupled to IR video cameras are being developed for night vision surveillance.
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From page 166... ...
A decrease of a factor of 5 to 10 in solar cell cost would make the price of solar photovoltaic electrical energy comparable to that for nonrenewable sources. If the cost of solar photovoltaic cells continues to decline, solar cells could begin to impact the electric power industry by 2020 and could provide as much as half the world's electric power by 2050.
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From page 167... ...
1 995. Solar Cells and Their Applications.
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From page 168... ...
Warner, I.M., S.A. Soper, and L.B.
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