Optics and Photonics Essential Technologies for Our Nation (2013) / Chapter Skim
Currently Skimming:
Appendix C: Additional Technology Examples
Appendix C: Additional Technology Examples
Pages 288-330
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 288... ...
DEFENSE AND NATIONAL SECURITY This section discusses the changes in many of the areas that were addressed in "Optics in National Defense," Chapter 4 of the National Research Council's (NRC's) 1998 Harnessing Light: Optical Science and Engineering in the 21st Century.1 The subsections below provide an update for the areas of surveillance, night vision, laser systems operating in the atmosphere and in space, fiber-optic systems, and special techniques (e.g., chemical and biological species detection, laser gyros, and optical signal processing)
|
From page 289... ...
Average power levels are approaching the kilowatt level, and pulsed amplifiers with peak powers approaching 100 kW have been demonstrated.2,3,4,5 Several vendors are offering lasers with output powers up to 150 W There are also several vendors offering narrow line-width, rapidly tunable 2.1 µm laser sources.
|
From page 290... ...
6 See, for example, IPG Photonics, "2 Micron CW Fiber Lasers." Available at http://www. pgphotonics. i com/products_2microns.htm.
|
From page 291... ...
-constrained platforms. Laser Rangefinders, Designators, Jammers, and Communicators The significant increase in laser diode efficiency coupled with the decrease in cost has enabled recent advances in laser designators.
|
From page 292... ...
Special Techniques The special techniques (i.e., chemical and biological species detection, laser gyros, and optical signal processing) evaluated in the NRC's 1998 report11 have evolved in different ways.
|
From page 293... ...
A new advance since the 1998 report is in the area of star-trackers, which can augment inertial naviga tion systems to improve long-term stability. Optical Signal Processing Optical processing has not changed very much since the NRC's 1998 study.14 It continues to be very promising, since some mathematical functions can be performed very rapidly using optical analog techniques.
|
From page 294... ...
Technologies such as mounts for solar modules and electronics are also crucial to the commercialization of solar power technologies. Work has been done to model the competitiveness of a given solar technology quantitatively given the variability of many uncertain factors.
|
From page 295... ...
FIGURE C.3 An updraft solar tower power plant scheme. SOURCE: Redrawn and slightly modified by Cryonic07.
|
From page 296... ...
A sample output of SAM is shown in Figure C.4, although the program produces an enormous amount of information and only a small part of the output is rep resented in the figure. Models that can predict the performances of solar power relative to alternate sources of energy have been developed.
|
From page 297... ...
An approximate cost breakdown of these components is presented in Table C.1.19 The electronics cost is substantially reduced for concentrating solar power (CSP) systems, as the generator can produce AC power directly to the grid and the battery is unnecessary.
|
From page 298... ...
Optics and Photonics in Diagnostics The high-speed blood work mentioned in Chapter 6 can also help determine the status of the patient's immune system. When the AIDS epidemic was first detected in the early 1980s, the cause of the disease was unknown.
|
From page 299... ...
These key portions of a patient's genome are measured today in optical instruments that can quantify millions of sequences in a single test using optical lithography technology, which was developed originally to manufacture integrated circuits and was modified to work with DNA molecules. The activity levels of specific genes can provide insight into the causes of tumor growth and thus allow oncologists to prescribe the most effective drugs.
|
From page 300... ...
Biomedical Optics in Everyday Life Glucose Monitors Optical methods are also used to monitor chronic conditions, such as the monitoring of the glucose level in diabetic patients by means of compact, cell phone-sized, battery-operated readers that analyze the concentration in the blood serum. These devices use optically active reagents that react with glucose in a small blood sample placed on a very inexpensive disposable paper strip and change the optical properties of the strip depending on the amount of glucose in the sample.
|
From page 301... ...
, called phase variance optical coherence tomography (PVOCT) , appears to have the potential to eliminate the need for the administration of an intravenous fluorescent dye, thus making this procedure much safer.
|
From page 302... ...
This process can now be performed with phenomenal precision using laser surgery guided by OCT data.22 Advances in Endoscopic Surgery Prosthetic devices can restore hearing in many older adults who have experi enced degenerative hearing loss and in children born with hearing deficits. Insert ing these devices often requires delicate surgery in the close environment of the ear canal, surrounded by very delicate tissue structures.
|
From page 303... ...
procedure. telecommunications industry, several new types of fiber-optic cables have been developed that allow the effective delivery of mid- and far-IR lasers, wavelengths that are highly absorbed by soft tissue, into previously inaccessible portions of the human anatomy like the inner ear.
|
From page 304... ...
utilize submicron layers of optical materials surrounding a hollow core, which al lows the far-IR light from the CO2 laser to be delivered to delicate bone and tissue structures of the inner ear. This new fiber-coupled source has found great utility in otology, providing effective methods for the surgical implantation of prosthetic devices restoring hearing to adults and children who have hearing impairments.
|
From page 305... ...
These optical signatures, as indicated in Figure C.7, can be used to diagnose quickly and noninvasively the cause of hypoxia and can help determine the most effective treatment. Rapidly growing tumors require high blood flow to supply sufficient nutrients and oxygen to support tumor growth.
|
From page 306... ...
Using high-efficiency fluorescent organic dyes and low noise detectors, single DNA molecules with specific sequences can be detected even when contained in a sample with a large concentration of background DNA molecules. This high sensitivity and specificity have allowed the development of techniques that separate the sample into multiple individual wells, where the number of wells is large enough that only a single molecule is likely to be in any individual well.
|
From page 307... ...
Hydraulic injection molding presses and injection compression molding presses are now employed by most optical FIGURE C.8 (Left) A commercially available 5-axis computer numerically controlled grinder.
|
From page 308... ...
°C 72 88 82 170 Water absorption 3% 0.3 0.25 0.2 0.25 Haze % 1-2 2 2-3 dN/dN × 10–5 /°C −8.5 −10 to −12 −12 Color/tint Water clear Water clear Water clear Amber Benefit 1 High transmission High transmission High index Impact resistant and purity and purity Benefit 2 Scratch resistance Excellent UV Clarity Thermal and Chemical resistance properties chemical resistance Benefit 3 High Abbe value 82% transmission High index Low dispersion at 924-301 nm, 1 High melt flow mm CT SOURCE: Courtesy of Syntec.
|
From page 309... ...
During the past decade, domestic and offshore manufacturers have marketed systems capable of producing precision-molded glass lenses. Figure C.9 shows a molding machine developed and produced in the United States and com mercially available around the world, and Figure C.10 shows molding inserts and molded asphere lenses.
|
From page 310... ...
310 Optics and Photonics: Essential Technologies for O u r N at i o n FIGURE C.9 Commercially available glass molding machine. SOURCE: Courtesy of Moore Nanotech, LLC.
|
From page 311... ...
FIGURE C.11 Moldable glasses types available from Rochester Precision Optics. SOURCE: Courtesy of Rochester Precision Optics.
|
From page 312... ...
The quality of lenses produced from the glass molding process is highly de pendent on the ability to produce molding tools. Molding inserts are single-point diamond turned or ground and post-polished.
|
From page 313... ...
as a fabrication process for optical components has grown in popularity since the mid-1970s. SPDT is now routinely used to produce finished optical elements as well as mold inserts for polymer lenses and glass molding.
|
From page 314... ...
314 Optics and Photonics: Essential Technologies for O u r N at i o n produce the required components. Polycrystalline materials are more difficult to machine and generally considered not diamond-machinable.
|
From page 315... ...
FIGURE C.14 HELIOS advanced plasma reactive sputtering tool. SOURCE: Courtesy of Leybold Optics.
|
From page 316... ...
Extremely tight toler ances for some of these aspheric geometries are the challenge for available metrol ogy. Testing variability for ultrahigh-precision optics, as in optics for lithographic applications, often needs to be 3 to 5 times smaller than the tolerance of the optic being measured.
|
From page 317... ...
Another advancement, shown in Figure C.16, combines laser Fizeau interferometry and displacement measuring interferometry to reduce measurement uncertainty. Gray-Scale Lithography for Diffractive- and Micro-Optic Components Gray-scale lithography has become an important method for the fabrication of diffractive- and micro-optical components for optical systems applications spanning the range from the deep UV (193 nm)
|
From page 318... ...
the surface-relief pattern directly into the substrate material. Common substrate materials for reactive-ion-etched optical components include fused silica, silicon, and germanium.
|
From page 319... ...
The polarizers are crossed, but in the absence of electric current, the thickness of the liquid-crystal layer is such that it rotates the polarization by 90°, so light is passed. Applying an electric field alters the alignment of the liquid crystal so that the light is not rotated and light is thus blocked.
|
From page 320... ...
The first-generation three-dimensional LCD televisions used such active shutter glasses, seen in Figure C.20. The shutter glasses were themselves crude LCDs, consisting of a single large pixel per eye.
|
From page 321... ...
Svedberg. this solution meant that the shutter glasses for any one eye were passing light only during one out of four frames.
|
From page 322... ...
One might expect brightness to be an issue with an active retarder as it is with active shutter glasses. However, the brightness issue can be greatly reduced by synchronizing the two displays and segmenting the backlight.
|
From page 323... ...
This coupling is attenuated by a finger touching the cover glass, which provides a path to ground through the body. This reduction in capacitive coupling can be measured, and based on the readings from each unit cell the center of the touch position or positions can be interpolated to higher resolution than the cell spacing.
|
From page 324... ...
There have been efforts within the industry to eliminate the separate substrate that is dedicated to the touch sensor function. Of the existing substrates considered for integration with this function, the leading candidates are the underside of the cover glass and the face of the color filter glass.
|
From page 325... ...
If a large sheet of uncut cover glass were to be ion exchanged, after which the transpar ent conductors were patterned, dicing individual covers from the large sheet would be difficult because the sheet already had been ion exchanged. Even if success in dicing were achieved, this still would be problematic because none of the exposed edges would have been ion exchanged, and thus central tension would be exposed.
|
From page 326... ...
Although the dedicated touch substrate is commonly bonded directly to the cover glass, the bonded assembly itself is only sometimes bonded to the front polarizer of the display. Such direct bonding results in additional coupling of display noise, which is a particularly challenging problem with larger displays, like those of tablets, since ITO is such a poor conductor.
|
From page 327... ...
2012. "Optical Touch Overview." Available at http://www.nextwindow.com/optical/.
|
From page 328... ...
Cover glass, by contrast, has relatively high thermal expansion, as this is currently thought necessary to achieve a glass capable of ion exchange. Nevertheless, if an internal polarizer were to be achieved, researchers would be highly motivated to create a glass that combines cover and color filter functionality.
|
From page 329... ...
Amorphous oxides could do more than simply serve as passive electrodes. They could also replace amorphous silicon as the active semiconducting material in TFTs.
|
From page 330... ...
silicon devices; thus the display industry can leverage much of the existing infrastructure and know-how. A key advantage amorphous oxides hold over amorphous silicon is their higher charge-carrier mobility.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.