This category covers establishments primarily engaged in manufacturing instruments and apparatus that measure an optical property and optically project, measure, or magnify an image, such as binoculars, microscopes, prisms, and lenses. Included are establishments primarily engaged in manufacturing optical sighting and fire control equipment. Establishments engaged in manufacturing contact lenses and eyeglass frames and lenses are classified under SIC 3851: Ophthalmic Goods.
333314 (Optical Instrument and Lens Manufacturing)
Companies in this industry manufacture a plethora of devices, including weapon-firing control mechanisms, optical laser-sighting systems, binoculars, borescopes, camera lenses, contour projection apparatus, gun sights, opera glasses, interferometers, microscopes, telescopes, periscopes, and spyglasses. Most devices in this industry use lenses. Some products, however, do not utilize lenses, such as rifle-aiming circles and some types of surveying equipment; they simply help users to align or measure objects. Electronic optical devices that do not use glass or plastic lenses, like the electron microscope, are classified elsewhere.
Long-term growth in the industry will depend on the ability of U.S. companies to continue to introduce new optical technologies and improve on existing ones, such as advanced laser-optics, new liquid-crystal devices, and scanning equipment. The latter, used for business, home, security, and banking purposes, has been one of the most promising areas for the optical industry. Infotrends Research Group Inc. predicted that eight million scanners would be sold by the year 2000.
The largest segment of this industry—about one-third of industry sales—is sighting, tracking, and fire control equipment, much of which is used in missile systems, combat aircraft, and other defense applications. Optical test and inspection equipment, which makes up about 7 percent of sales, includes a variety of mechanisms. Much of it is used by other industries, like automobiles and steel, for quality control and other purposes. About 4 percent of industry output is in the form of binoculars and astronomical instruments, and about 3 percent consists of microscopes. About half of the industry's sales are garnered from miscellaneous devices.
Most products in the industry use compound (more than one) lens systems. A series of several convex and/or concave lenses often is used to magnify light reflected from an image. Although a single convex lens theoretically will focus incoming light, such a system typically suffers from defects that cause blurring and distortion. Therefore, many lens systems, such as those in cameras, use eight or more lenses in series or cemented together to reduce aberration, coma (blurring), and distortion.
Lenses typically are manufactured from glass in a process called grinding. First, the glass is cast in blocks, strips, panes, and rods, or it may be molded into a rough lens form. Then it is cut and rough-ground using a diamond abrasive on a grinding wheel. Fine grinding is accomplished using a silicon carbide or emery abrasive. For fine optical instruments, final polishing may take several hours using a precise lapping tool. Finally, the edge of the lens is ground so that its axis is centered precisely. Sometimes the lens is coated with a substance that reduces distortion. In addition to glass, transparent plastics also are used for lenses. They are simply molded, rather than ground.
Modification of simple glass lenses has been practiced since ancient times, but the development of compound lens devices did not occur until 1600. That year, Dutch lensmaker Hans Jannsen and his son, Zacharias, mounted sliding lenses in a tube to form the first simple microscope. In 1611, a compound lens system that used a convex lens in the microscope's eyepiece was built by Johannes Kepler.
Historians often credit Hans Lippershey of Holland with inventing the telescope in 1608, when he accidentally aligned two lenses of opposite curvature and different focal length. The concept, however, may have been first understood in the thirteenth century by friar Roger Bacon. Galileo Galilei developed the first lens, or refracting, astronomical telescope in 1609. Christian Huygens improved Galileo's design soon afterward, with a telescope that reduced aberration. While these simple devices suffered a variety of defects, they achieved useful results.
During the remainder of the seventeenth century, compound optical instruments were vastly improved to increase magnifying power and reduce distortion. Important developments included Isaac Newton's design of a reflecting telescope that used mirrors to reduce aberration in 1668. Innovations during the eighteenth century largely reduced aberration and distortion in both telescopes and microscopes, resulting in apparatus that closely resembled the instruments commonly used during most of the twentieth century.
Early in the twentieth century, optical apparatus manufacturers focused on increasing power, or magnification. New lens manufacturing and mounting techniques allowed significant gains in this area. Conventional glass lens magnifying technology, however, was approaching its limit. Large refracting lenses suffered from distortion caused by sagging under their own weight. After World War II, scientists began searching for optical instruments that used alternatives to glass lenses, such as radio waves and magnetic lenses, to improve microscope and telescope devices.
In addition to the development of optical devices that did not use glass lenses, new types of optical devices emerged during the mid-1900s. Optical apparatus that could be used to control laser beams, for example, became an important industry offering. And the creation of new electro-optical devices opened up entirely new markets in other industries. By the 1980s, electro-optical equipment was being used to analyze and control manufacturing processes, guide missiles, operate audio-visual systems, and perform many other functions. Optical interferometers, for example, were developed to measure wavelengths, and optical metallographs were created to study the structure of metals and their compounds.
According to the U.S. Census Bureau, there were at least 500 companies engaged in the manufacturing of optical instruments and lenses in the late 1990s. The industry employed approximately 22,100 persons, and generated about $3.74 billion in shipments in 2000. States with the most establishments in the industry were California, Massachusetts, and New York. The industry could be divided into two major product classes: more than two-thirds of revenues came from companies manufacturing optical lenses and equipment (such as binoculars, camera and microscope lenses, and astronomical instruments), while the remaining segment of the industry produced optical sighting, tracking, and fire-control equipment.
In the late 1990s, several new optical products appeared on the market, keeping industry leaders in keen competition. On the verge of widespread product application were "switchable optical elements" (SOEs)—new devices that combined diffractive structures with electro-optical components. Potential commercial applications of SOEs included reading glasses that changed magnification degrees electronically, windows that redirected sunlight to the ceiling for more diffuse room light, camera lenses that zoomed from wide-angle to telescopic without moving parts, and sunglasses with lenses that darkened with the flip of a small switch located in the frame.
With much of the demand coming from the military and law enforcement sectors, a rapid increase in commercial applications was expected in the night-vision optical device market (including night-vision goggles and scopes), which had grown to $404 million by 1997.
In 1999 scientists optically recorded the most volatile cosmic eruption ever detected—capturing a gamma ray burst from nine billion light years away. The images were taken at the Los Alamos National Laboratory with a telephoto camera having the acronym of ROTSE-1 (Robotic Optical Transient Search Experiment 1). The system incorporated space satellites that, upon detecting bursts, alerted ground telescopes that in turn scanned the sky in the identified region.
On the forefront of telescopic technology was the linear tracking of stellar/heavenly bodies, replacing traditional tape encoders. In 1998 the first Heidenhain LIDA 105C exposed linear encoder was supplied to an 8m Gemini telescope on the top of Mauna Kea, Hawaii; the second was to be added to another 8m Gemini in Cerro Pachon, Chile, after its completion at the TELAS/NFM factory in France in the year 2000. These systems allowed telescopes to pinpoint specific areas of the sky with extreme accuracy.
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