Ahn and B. Kim Opt. Kersey, A. Dandridge, and A. Tveten Opt. McGarrity, B. Chu, and D.
Jackson Appl. Yun, G. Tearney, J. Bouma Opt. Express 12 23 You do not have subscription access to this journal. Citation lists with outbound citation links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution. Cited by links are available to subscribers only. Figure files are available to subscribers only. Article level metrics are available to subscribers only. Login or Create Account. Allow All Cookies. Optics Letters Vol. Brooks, M. Tur, B. Kim, K. Fesler, and H. Shaw, "Fiber-optic interferometric sensor arrays with freedom from source phase-induced noise," Opt.
Low-Cost Interrogation System for Long-Period Fiber Gratings Applied to Remote Sensing
Not Accessible Your account may give you access. Abstract We propose arrays of all-passive remote sensors with freedom from both source phase-induced intensity noise and cross talk between sensors. 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. Most physical evidence is currently examined by standard chemical analysis, with little use of optical instrumentation except optical microscopes.
Confocal optical scanning microscopes with high spatial resolution are now being used in Canada but not the United States. Two exceptions are the enhancement of fingerprints by laser fluorescence and the detection of some bodily fluids blood, semen using filtered lamps to excite fluorescence of the specimens Menzel, The latter technique is employed at crime scenes where portability is important, in contrast to the laser-enhanced fingerprint system, which is laboratory based because of the large laser size.
This situation is expected to change as new, efficient, compact diode-pumped UV lasers and time-resolved imaging systems are developed. The analysis of DNA evidence uses laser tagging of the DNA sequencing segments; it is just starting to be employed by law enforcement agencies. However, as always, care must be taken to ensure that the evidence is not contaminated with additional DNA specimens.
This requirement shows the need to develop self-contained portable laboratories for the analysis of evidence.
Fiber optic sensors in environmental monitoring
It is felt that low budgets and lack of training are hindering growth in this area in the United States. Finally, optical systems will play a greater role in the detection of counterfeit money since most anticounterfeit sensors will use optical or holographic techniques to detect hidden patterns and embedded markers in the bills.
This will be a growth area as U. A variety of optical sensors and instruments are used every day and manufactured in large quantities; in some cases, these represent significant financial markets. Although some of these devices are discussed in Chapter 6 , they are listed here because they rely on optical sensors as the basis of their function. Examples include optical bar-code readers, garage and elevator door safety sensors, television remote controls, ''ear" infrared thermometers, night-activated photoelectric light switches, infrared coupling 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 to scan and detect the reflected light from the pattern of the bar-code. Bar-code scanners are now used on most manufactured goods for inventory control, including rental cars, railroad cars, packaged food, parcel delivery, and most items sold at retail; Figure 3.
Garage door and elevator door safety stops often use an invisible infrared beam directed across the bottom of the door, so that someone in its path can be detected and closing of the door stopped; a similar photoelectric eye is used to record and time track, ski, and race events.
Television remote control devices "clickers" work by emitting a very low power, pulse-coded infrared LED beam that is detected and interpreted by the television set as an instruction to change channels and so forth. These devices have proven accurate and are very important for use on children.
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Photoelectric switches have been used for more than 50 years to turn city streetlights on and off according to how dark it is; they have also. Courtesy of Metrologic Instruments. Automated infrared proximity sensors are used in many public restrooms to turn on faucets and lavatories.
A variety of optical sensors are used in common devices related to communication and information processing. Fax machines use a long linear array of optical sensors to measure and image the scanned input paper for subsequent transmittal over phone lines. Optical copiers use either a traditional light source a xenon lamp for black and white prints or a laser scanner to image and form a color print.
The laser computer printer has been widely available for the past 10 years and uses a semiconductor diode laser to write extremely small dots onto a toner cartridge and paper. DOE, NIST, and industry, in cooperation with the technical and professional societies, should pursue a program to enhance the coordination and transfer of optical sensor technology among industry, academia, and government agencies. One of the most important uses of optics by society is in the form of lighting.
Lighting systems represent a major economic market, with annual U. Because these numbers are so large, a small increase in lighting efficiency represents a large savings of energy and cost. 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.
It should be noted that several U. Artificial lighting is a rather recent technological advance in terms of human history, having become a useful technology only within the past 50 to years. Historically, artificial lights existed for thousands of years in the form of fire torches , but this changed radically with the invention of the incandescent lamp in the s by DeMoleyns and Starr, followed by the first successful commercial mass-produced lamp in by Edison. Similarly, low-voltage fluorescent lamps were invented by Meyer in , followed by their commercial production in by the General Electric Company.
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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 and LED light sources. One measure of the utility of these different light sources is the output light generated lumens per input electrical energy watts , including any ballast electronic losses.
Although the figure is interesting and shows the improvements expected in several new light sources, it is only a part of the story and does not indicate several very important, photometrically related visual parameters such as 1 color index efficiency ability to view different colors ; 2 changes in human visual color response at. Note that the color rendition of the human eye, night-time visual sensitivity, and the ability to distribute or focus light are not taken into account in this plot.
All of these factors influence the efficacy effectiveness of the light source, including its efficiency, the directional nature of the ability to focus light lumens per steradian of solid angle , the efficiency of distributing light to a distant place, and the human visual response color and contrast at different light levels. For instance, although sodium lights have a high-efficiency in terms of lumens per watt, they are poorer for viewing colors at night than metal halide sources.
Also, although incandescent or halogen lamps have a lower lumen efficiency than fluorescent lamps, they are more effective in delivering light to a specific location e. On the other hand, the sulfur-dimer lamp has very high-efficiency, but it is more difficult to deliver the light efficiently to distant locations where it can be used by people to see. For these reasons, it is important that light sources be judged not only on their energy efficiency but also in terms of human visual response and ease of distribution.
halmanetla.tk A set of standards encompassing all of these effects is being worked on by universities, industry, and government agencies, but it has yet to be universally adopted. Such standards would be extremely helpful in light source selection and would help to direct future research in this important area.
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. This section discusses some recent exciting developments.
Related Remote Sensing Photography Using Fiber-Optic Technology
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