Harnessing Light Optical Science and Engineering for the 21st Century (1998) / Chapter Skim
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6 Manufacturing Optical Components and Systems
6 Manufacturing Optical Components and Systems
Pages 235-274
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As new mass consumer markets have emerged that rely on optical technology such as compact disk (CD) players and laptop computer displays the implementation of high-volume mass-manufacturing techniques similar to those of the electronics industry has revolutionized this segment of the optics industry.
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From page 236... ...
optics industry's ability to compete internationally in the increasingly important mass markets, especially the new mass markets that continue to emerge? Following a brief history of optics manufacturing in the United States and a short overview of the current state of the industry, the chapter divides into two main parts: (1 )
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An Overview of the Industry Today The nature of the optics industry continues to change. Mass production techniques are used to manufacture components for an increasing C h a p t e r 6 237
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The United States excels in this high-value, low-volume portion of the optics industry. Most of the industry that serves the low-volume, high-accuracy component market remains dependent on very traditional fabrication methods, although it is increasingly facilitated by high-quality interferometric test equipment.
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From page 239... ...
and thermal analysis software would be even more effective if fully integrated into optical design software. Manufacturing of optical components and systems requires a large skilled and semiskilled workforce, and emerging new mass markets will increase the optics industry's need for trained workers.
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DOD should continue to maintain technology assets and critical skills in optics manufacturing in order to meet future needs. Some government projects require so many specialized optical components that they have a significant impact on the entire optics industry, despite the low volume for each of their individual components.
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This is the Center for Optical Manufacturing (COM) at the University of Rochester, which has made significant progress in the development of high-speed machines to generate surfaces that require C h a p t e r 6 FIGURE6.1 A single spherical-surfaced lens (left)
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Although most spherical optical components are produced for use in imaging systems, other applications are also important for a healthy U.S. optics industry.
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is investigating the fabrication of conformal optical components. Except in some infrared applications, machined aspheric surfaces usually require a computer-controlled polishing or finishing step.
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It is vital to the future of the U.S. optics industry that domestic production of aspherical optical components be made more cost-effective.
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COM's major thrusts are the integration of computers into optical component manufacturing, the development of computercontrolled optical component manufacturing equipment, the development of deterministic processes using this equipment, and the transfer of the resulting technology to industry. Some of the key challenges being addressed include improved inspection techniques for in-line process control, new machine geometries for making aspherical parts, and improved tools for optomechanical design.
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From page 246... ...
Optical Coatings The last step in making an optical component, especially a highvalue component, is often to apply a thin film of light-controlling or protective coating. These coatings range from simple metallic reflectors, to antireflection coatings, to multiple-layer filters, to high-efficiency dielectric reflection-enhancing bandpass coatings.
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From page 247... ...
Roll coalers can be used for some low-precision applications on flexible substrates. Among the technical issues for optical coatings are cost, durability, low body and surface scatter, high efficiency, production yield, and environmental stability.
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Optical Glasses, Polymers, and Specialty Materials A wide variety of optical materials are used in image-forming components. In addition to their optical properties such as transparency and index of refraction, practical considerations such as isotropy, homogeneity, and environmental stability are usually also important.
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Other optical materials tailored for particular applications include ultrapure silica for optical fibers, erblum-doped glass for fiber amplifiers, and sol-uel materials for specialized filters and wave~uide devices: some ~ , ~ , ~ .
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To achieve such astonishing performance the lens must be fabricated and assembled to near-perfect tolerances. Important manufacturing issues for future systems include image and tolerance modeling, surface figure, surface finish, metrology, asphere production, mounting, and production of short-wavelength sources.
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optics industry. Case Study: Optics for the National Ignition Facility Government programs are another major customer for high-value specialty optics.
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optics industry. From development through production, approximately $200 million will be spent on optical components for the program.
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Key Technical Challenges Among the major challenges in the design and fabrication of lowvolume optical components are the following: The cost-effective manufacture of general aspherics and conformal components and their use in a wide variety of instruments and devices; Deep-UV optics for microlithography to permit the continued reduction in feature size and enlargement of chip area that will take the semiconductor chip industry through several more cycles of economy and speed; and Low-cost, low-volume, surge-capable optical manufacturing, which is essential to maintain efficiency and support the continued devel opment of mi I itary optical systems. High-Volume Manufacturing of Optics The high-volume mass production portion of the optics industry uses manufacturing methods quite different from those discussed above and faces its own technical and structural challenges.
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From page 254... ...
The advent of the erblum-doped optical amplifier in the late 1 980s revolutionized systems design by eliminating the need to regenerate signals electronically every few tens of kilometers to compensate for attenuation by the optical fiber. Even more importantly, the optical ampl if ier made WDM practical for the first time, by making it possible to route individual wavelengths separately in a point-to-multipoint BOX 6.1 THE IMPORTANCE OF MATERIALS SCIENCE AND ENGINEERING IN OPTICS MANUFACTURING Materials production and materials processing are essential enabling elements in the manufacture of optical devices and systems.
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Further advances in optical telecommunications will depend on continued cost reduction and increased functionality and integration. Such advances will require the introduction of high-volume manufacturing technology that incorporates automated production lines and on-line process controls.
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From page 256... ...
High-power fiber lasers, Raman amplifiers, dispersion compensators, and fiber-grating filters and reflectors are now reaching the commercial marketplace. Such devices will be integral parts of broadband telecommunications networks as well as nontelecommunications applications such as optical sensing, optical gyroscopes, automobile collision avoidance, and medical applications.
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, laser arrays, low-cost packages, and higher-power lasers; Developing practical green, blue, and ultraviolet lasers; and Developing high-performance, low-cost imaging arrays. For all photonic components, performance is critically dependent on materials quality, composition, and control (see Box 6.2~.
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As materials processing improves and the integration of multiple photonic components on a chip becomes standard, however, continuous improvements will be required in substrate material quality. In the meantime, materials processing does remain the major limitation on the wafer yield of complex photonic devices, and improvement in all aspects of process control and equipment design will be essential in achieving the high yield and low cost required to make extensive photonic integration viable.
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A recent advance in the cladding-pumped fiber laser is the enormous (approximately a thousandfold) brightness conversion of GaAIAs laser arrays in an optical fiber.
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The most troublesome issue has no counterpoint in electronics, however. The issue is coupling an external optical fiber connection to an optical waveguide with submicron tolerances.
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optical design, including coupling, mode matching, minimization of reflections, polarization management, connectorization, and stability to submicron tolerances; (2) physical design, including support of the fragile photonic chip materials, stress, ease of assembly, and standards; (3)
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This section discusses two technical issues of this type, optical design and the role of metrology, and two structural concerns, the question of standards and the difficulty of identifying and characterizing the "optics industry." Optical Design and the Impact of Increased Computer Power The development of effective and comprehensive optical design programs that are capable of handling a wide variety of optical components is a success story of the U.S. optics industry.
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The programs are remarkably capable with passive optical components, although there is as yet little integration of active optical components into the design process. The dramatic increase in computing speed and the simultaneous dramatic fall in computing cost have greatly influenced the optical design process.
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Better tolerancing is a challenge for the optical design community. Areas that need improvement include communication of the fabrication and testing limitations of the optics shop, communication of the tolerancing set and compensators, better understanding of the manufacturing cost breakpoints, and more enthusiasm for the tolerancing process.
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From page 265... ...
Improvements in software are necessary for the design and optimization of nonimaging components. Optical design tools must advance to handle integrated optical and mechanical design; for example, standards for representing precision surfaces are needed that are compatible with mechanical design programs.
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The ability to manufacture diffractive optical components with high throughput requires the ability to sculpt profiles on submicron structures to accuracies on the order of tens of angstroms. The advancement of microlithography requires concomitant advances in metrolo~v.
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Integrating optical design with mechanical design will require standards for the representation of precision surfaces. In the area of metrology, there are no recognized calibration standards for surface roughness, scattering, or cosmetic defects.
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optics industry has been a follower, not a leader, in adapting to new international opportunities. Active government and industrial participation in the setting of strong international standards for optical components is especially important because of the diversity of the U.S.
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approach $8 billion, which represents an average annual increase of 10% (see Table 6.2~. This growth rate is probably representative of the optoelectronics industry as a whole, but the survey was not all-inclusive, and so the exact size and composition of the industry are not known (U .S.
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Cathode-ray tube displays 16.3 1.8 Data storage (media only) 13.0 1.0 Flat-panel displays 11.5 0.2 Sensors (including imaging)
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industrial base, much of the optics industry appears to have been overlooked. For example, the new North American Industry Classification System (NAICS)
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From page 272... ...
Thus, although the industry makes a significant contribution to the economy, this contribution comes in so many small pieces that it is hard to fully recognize and understand. Annual revenues are in the tens of billions of dollars, but precise characterization is difficult because the optics industry does not align well with the government's standard statistical categories.
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Optical design is a key strength of the U.S. optics industry.
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From page 274... ...
DOD should continue to maintain technology assets and critical skills in optics manufacturing in order to meet future needs. The Bureau of the Census should involve representatives of the optics industry in the next revision of the NAICS codes.
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