Although advances have been made in some of these areas, for the most part the fundamental way we observe and see our immediate surroundings has not changed significantly over the past hundred years, with the exception that now artificial lenses and surgical techniques can improve some vision problems and better eyeglasses and corrective procedures are available. What is significant, however, is the tremendous advance that has occurred recently in the development and use of new optical and infrared sensors and instruments that can detect and analyze our surroundings and present this information to us visually, thus greatly augmenting our normal visual process and in some cases showing details and information never previously seen.
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 evening news, infrared night 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.
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Related to these advances in optical sensing and imaging technology are associated advances in the development of new, high-efficiency. For example, new lighting sources are being developed that may reduce U. This chapter presents a synopsis of recent advances in optical sensing instruments and techniques, lighting, and energy. The emphasis is on new or revolutionary optical technologies that are expected to significantly impact the future growth and well-being of our society. As such, technical areas of lighting, energy, and optical sensors that either are mature or are not expected to grow dramatically are not covered in as much depth.
Although the topics include a rather broad range of optical fields, they are centered primarily on the generation of light new lighting sources , the conversion of light to energy solar cells and laser fusion research , and the use of optical and imaging sensors for the measurement and detection of a wide range of physical and chemical parameters night vision scopes, video cameras, gas vapor sensors, traffic laser radars, bar-code scanners. The role that advances in materials have played in many of these fields is also addressed, because the development of new optical materials is often the key factor enabling progress Box 3.
The total world market is estimated to be two to three times as large. Some of these applications have a great impact on other markets and represent key or enabling technologies. The development of new optical and semiconductor materials has been a key factor in the recent advances made in optical detector arrays, optical biosensors, digital cameras, lighting sources, and solar cell efficiency.
Another example is the real-time global mapping supplied by space-based optical imaging weather satellites.
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These maps affect a much larger market for weather and crop forecasts and help authorities develop forecasts and emergency plans for storms and hurricanes whose impact in dollars and lives saved is often incalculable. Where practical, these secondary impacts of optics applications are also covered in this chapter.
The discussion of each subtopic is based on the results of a workshop held by the committee, as well as on additional written inputs obtained by the committee. The main findings and conclusions, which cover key highlights and challenges, are collected at the end of each major section.
Finally, recommendations based on the findings and conclusions are made to the government, academia, and industry, where appropriate. Light reflected from objects has been used by humans for thousands of years as a way to see or remotely sense the presence and composition of the surrounding environment.
In most cases, the reflected or transmitted light is seen directly by the eye, and differences in color or intensity over the visible wavelength spectrum are used to detect and differentiate objects and images. Although outside the portion of the spectrum that is visible to the eye, light at ultraviolet UV and infrared IR wavelengths contains additional information. For instance, absorption and possibly fluorescence at UV and IR wavelengths can be used to detect certain chemicals and pollutant gases, to see objects at night by using IR thermal radiation, and to measure the temperature and composition of a distant object.
It is the spectroscopic or wavelength color dependent nature of the reflected or transmitted light that allows one to detect a particular feature or the presence of a particular chemical. 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.
Although spectroscopic optical instruments have been used for the past hundred years, recent advances in these optical techniques and the reduction in their costs have led to the recent surge in their use in a wide variety of fields. 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.
Optical systems can be used for the detection of a number of important gases or pollutants in the atmosphere. In many cases, each chemical has a distinct absorption spectrum in which different wavelengths or colors of a transmitted optical beam are preferentially absorbed according to the concentration and presence of the chemical or gas in the atmosphere. Several different optical techniques are used, depending on the substance of interest, its concentration, and the detection range expected from the instrument.
An important point is that optical sensing can often be accomplished remotely, because the optical beam can be directed at a distant object and information about the composition and gases surrounding the distant scene can be deduced from backscattered light. In fact, optical remote sensing can be used to detect chemicals or physical parameters such as speed and dust cloud density at ranges from a few meters to several hundred kilometers in some cases.
This capability has significantly changed the way we measure our environment. For instance, 30 years ago weather balloons were used to carry instruments aloft to sample the upper atmosphere; now, we use laser beams from the ground to make the same measurements. Similarly, where once we measured the severity of air pollution in Los Angeles by measuring the time it took a stretched rubber band to rot, we now use chemical and optical absorption instruments to obtain round-the-clock coverage of the concentration of ozone and other environmental gases.
The advances in these areas are covered in the following sections. Optical gas monitoring uses a beam of light that is transmitted through the open air or through a sample chamber cell. The beams of open-air systems can cover paths of several hundred meters to several kilometers. Selective absorption of the light allows for detection of the compounds present and quantification of their concentrations. This is usually done by using a conventional optical spectrograph or a Fourier-transform infrared FTIR optical spectrometer that directs an. These optical instruments can be used as sensitive real-time monitors of the composition and concentration of environmental gases in the atmosphere or in a plume from a smokestack.
They have been used to detect the concentration of organics, refrigerants, carbon monoxide CO , nitrogen oxides NO x , ozone, and other gases in the environment and from industrial sources; to sense emission gases from automobiles over a highway; and to detect evidence of the manufacturing of chemical, biological, or nuclear materials.
For example, Figure 3. Although conventional analytical chemical techniques such as wet chemical analysis or gas chromatography are often used for this purpose, they do not offer real-time remote sensing or on-site capability as easily as optical monitoring does. The advantage of conventional chemical measurements is the longer historical use of these techniques and their lower capital cost, although their operational costs can be higher. The current annual U. The demand is driven by regulatory laws for source ambient air quality usage, although industrial process control is beginning to incorporate these techniques as well.
The recent increased acceptance of such optical instruments by the Environmental Protection Agency EPA will certainly stimulate their more widespread use. The main technical challenge is for smaller and cheaper laser or optical spectroscopy devices. At present, there is a significant U.techedbrains.com/assets/461/fyby-conocer-gente.php
Commercial + Scientific Sensing and Imaging
Courtesy of D. Hommrich, Essential Technologies, Inc. The slower U. Laser radar lidar 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.
Combined with spectroscopic wavelength control, tunable lidars have detected and mapped ozone, water vapor, methane, and other pollutant gases in the atmosphere or in smokestack plumes. In the effort to understand global climate change, lidars have been used to monitor gas concentrations and temperatures in the upper atmosphere and the concentration of ozone, water vapor, and methane over the Amazon jungle. If their sensitivity is high enough, range-resolved lidar returns can be used to map in three dimensions the physical extent of a plume or haze region; this was done to map the global movement of volcanic ash clouds from the eruptions of Mount St.
Helens and Mount Pinatubo.
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Airborne lidar systems have been used to make range-resolved maps of the density of haze over the Los Angeles basin. Figure 3. Also of.
Courtesy of E. This latter use will significantly increase our knowledge of the density of forests and jungle growth in remote sites, which is crucial for accurate predictions and understanding of the production of oxygen and uptake of carbon dioxide CO 2 by plants on Earth. A potentially significant new application for lidar will be its joint use with an open-path optical spectrometer instrument, since lidar can measure and map cloud or aerosol movements in three dimensions while the open-path instrument can determine the integrated gas concentration.
Such measurements would yield gas flux values, which are most vital for environmental and gas emission regulatory detection. Lidar instruments are still rather expensive and one of a kind; they are used more for research than commercial applications, with government funding for lidar still greater than private or commercial funding. The total U. Thus, the growth potential for lidar remains dependent on developments in lasers. One important use now being evaluated is for aircraft wind shear and wake vortex detection at airports.
Such a device would be an important enhancement to aircraft safety. Airlines, air cargo companies, and the U. Air Force are also interested in the use of on-board lidars for measurement of wind profiles below, above, and ahead of aircraft. Significant fuel savings could result from the use of such data.
At present, significant work in this area is being done in Japan and Europe, as well as in the United States. Another growing lidar market is for police laser radars to detect traffic speeds. 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.
The type of traffic lidar shown in Figure 3. Several U.