Fiber Optics Illustrated Dictionary - Part 58 pot

Ku-band is used primarily for data transmission, private networks, and news feeds.. The term was derived from the Universal Service Ordering Code USOC commonly used until the time ofthe

Fiber Optics Illustrated Dictionary

While Hansen went on to develop linear accelerators,

the Varian brothers and other scientists, including

their friend and associate, Edward L Ginzton, used

the technology to develop radar systems during World

War IT, cofounded Varian Associates in 1948

The radio waves in historic Klystron tubes are drawn

from a high-voltage electron beam in such a way that

much of the energy is dissipated, resulting in low

ef-ficiency levels compared with succeeding

technolo-gies However, klystron technology was never fully

superseded, especially in broadcast applications, and

some scientists felt the efficiency could be improved

The LewisNarian version ofthe klystron technology,

developed in the mid-1980s, recovers the wasted

en-ergy by recycling the electron beam, effectively

dou-bling the usable portion of the radio frequency and,

consequently, reducing power consumption in UHF

television transmitters Commercial production ofthe

new technology began in 1990 on the product now

known as the CPI MDC klystron

Commercial broadcasting klystrons come in a

vari-ety of configurations supporting frequency bands

such as the C-band at different channel capacities

(usually 6, 12, or 24) There may be separate tubes

for image and audio amplification Cooling with

wa-ter is typical in klystron applications where the tube

becomes hot See bunching; Ginzton, Edward; cavity

magnetron; magnetron; Varian, Sigurd and Russell;

Varian Associates

KMI Corporation A fiber optics and

telecommuni-cations market research and consulting firm founded

in 1974 KMI is a subsidiary ofPennWell and part of

PennWell's Advanced Technology Division, with

re-search headquarters located in Providence, RI KMI

publishesFiberoptics Market Intelligence® as a

semi-monthly newsletter and provides various

com-mercial market studies, fiber optic systems wall maps,

marketing workshops, and databases See FiberFax,

Fiberoptics NewsBriefs, Fiberoptic Undersea

Sys-tems, Undersea News Service

KMID key material identifier Aterm associated with

Message Security Protocol

KNET See Kangaroo Network

knife-edge focusing Focus (wavefront) testing, as for

scientific instruments such as telescopes This is an

aid to visually assessing a lens or mirror Often a

Ronchi screen or knife-edge bushing is placed as a

mask at right angles to the light path before or

be-hind the point of focus in relation to a lens or

con-cave mirror to provide the knife edge Focusing is

then adjusted until the edge "cuts" the light beam

exactly at the point offocus Ifthe lens/mirror is

per-fectly shaped, the lens aperture should darken evenly

Ifthere are aberrations, the combination oflight rays

before or behind the knife edge will create lighter

spots

The technique, developed by Foucault (sometimes

calledFoucaultsknife-edge test or Foucaultstest),

facilitates that testing of the surface quality of

vari-ous lenses and reflecting elements It is actually a

special case ofthe Ronchi test, for components where

the radius of curvature is double the focal length

For more complex instruments, or those commercially fabricated, interferometric testing is now routine How-ever, for home-brew or less expensive components, the knife-edge test is still practical and can be set up with readily available materials

A wavefront spatial filtering technique was suggested

by O von der Loehe (1988), developed from the Fou-cault test It uses two orthogonal knife edges to mea-sure the two components ofa wavefront gradient See pyramidic wavefront sensor, Ronchi grating

Knife-Edge Focusing

Knife-edgefocusing is afairly straightfOlWard con-cept In this example, incoming (incident) light that has been collimated (parallel beams) is aimed at a knife edge (B) used as a reference mask to determine the best focal point A Ronchi grating or knife-edge bushing may be used as the mask It is moved back and forth through the focal plane such that the pat-terns in the grating change as the light interacts with the pattern and will appear clear and even (rather than striped or patterned) at the sharpfocus point be-tween the beforefoeus(C)and beyondfoeus (D) points.

It takes a littlepractice and is a bit easier with a Ronchi bushing (rather than with a Ronchi screen).

Knife-Edge Testing - One Example

A knife-edge tester (Foucault tester) can be made fairly readilyfrom afew materials It is important that the support for the tester is stable and still The light source (A) projects onto the surface being tested (in this case, a concave reflector - B) and is reflected back through the knife-edge Ronchi grating or bush-ing (C) to the eye of the viewer (D) The eye is

posi-tioned so that the returning light is blocked by the knife edge Aberrations in the evenness ofthe surface will show up as bright spots, indicating a flaw.

Many commercial knife-edge testers magnify the im-age so that flaws are more readily apparent.

knife switch In old telegraph keys, a type of switch

that could short key contacts in a series so the idle line was in a steady mark condition, with current flowing - also called a break switch Opening the knife switch interrupted the current in all the sounder

made aware that a message was imminent.

knockout Araised or indented region ofa receptacle

which can be punched out or othetwise removed to

provide access for wires,jacks, or other fittings

Com-mon in general purpose electrical junction boxes

Knowbot Information Service KIS Auniform

cli-ent/server means ofinteracting with, and displaying,

information from a variety of remote directory

ser-vices typically found on Unix systems, such as

Fin-ger, Whois, and others A query to KIS uses white

pages services to these types of systems and displays

the results of the search in a consistent format See

Knowbots

Knowbots In a Knowbot Information Service,

pro-grams that search and retrieve information from

dis-tributed databases as requested by the user Knowbots

may carry the information or may pass it among one

another See Knowbot Information Service

knowledge base system, knowledge-based system,

expert system Acomputerized system of storing the

accumulated knowledge ofhumans in a system which

accesses and manipulates the information using

arti-ficial intelligence programming strategies and rules

to accomplish information delivery and

problem-solving at a sophisticated level

knowledge engineering Acquisition of knowledge

from a human expert or experts and its incorporation

into a computerized expert system

Knowledge Interchange Format KIF Computer

language for the manipulation ofknowledge data and

interchange ofknowledge among disparate programs

Intended not as a user interface, but as an internal

rep-resentation for knowledge within programs or related

sets of programs

Knowledge Query and Manipulation Language

KQML A high level language that is part of the

DARPA Knowledge Sharing Effort It is a language

and messaging protocol for exchanging information

and knowledge as part of the larger project to create

technology to facilitate development of large-scale,

shareable databases KQML can be used to support

interoperability among intelligent agents in

distribu-tion applicadistribu-tions See Reticular Agent Definidistribu-tion

Language

Knowlton, Kenneth C (1931- )AnAmerican

pio-neer in computer graphics and researcher at Bell

Laboratories, Knowlton studied and experimented

with many aspects of computer imagery, computer

art, motion automation, and fast data storage, often

in collaboration with L.D Harmon

In 1959, Knowlton co-authored a report for the U.S

Patent Office entItledA Notation System for

Trans-literating Technical and Scientific Texts for Use in

Data Processing Systems.As his explorations turned

to computer imagery, Knowlton grasped a concept

often overlooked by artists using traditional "paint"

tools in a computer environment: the computer can

be used to generate types of art and images that

can-not (or should can-not) be executed by human hands In

the course of his research, he and his collaborators

produced a rich variety of mosaics, plots, grayscale

Remember that these pioneers had to invent and write their own software systems for accomplishing their goals In the 1960s, no commercial desktop paint and animation programs were available off-the-shelf (they weren't common until 1986) Many goals were attained by typing in raw numbers in low-level lan-guages To aid him in automating the animation pro-cess, Knowlton developed a motion language for cre-ating short films Together with filmmaker Stanley VanDerBeek, he developed a series of abstract ani-mated films calledPoem Fields.The tools invented

to enable artistic visions to be derived from computer technology are applicable to many areas ofscientific research and manufacturing including digitization, pattern recognition, artificial intelligence, robotics, and more In 1979, Knowlton coauthored articles on visual perception and the use of sign language as a form of telephone communication, with Vivien Tartter

Over the decades, Knowlton's interests in image pro-cessing and image generation remained strong and

he has been awarded numerous patents for his work

As examples, in 1990, Knowlton and Wang Labora-tories applied for a u.S patent for what is essentially

an ebook, an electronic book viewed through a video display (#5283864, 1994) Following this, in 1994, Knowlton and Wang applied for a patent for a docu-ment processing system including an optical scanner (#5517586, 1996) See Harmon, Leon; Shroeder, Manfred

Knuth, Donald (1938-) Knuth's texts on data struc-tures and algorithms are heavily used, and widely considered by programmers to be the "bible" of im-portant basic programming structure information Fundamental search and distribution trees and much more are in the Knuth texts It would be difficult to develop sophisticated database software without them Knuth is also known for authoring the power-ful document system called TeX(pron. tek), which

is one ofthe few that can handle complex mathemat-ics-related text formatting

KOLD-TV A pioneering digital broadcast station, KOLD 13 began using a networked digital video server in daily broadcasts in 1995 In October 1998, the Federal Communications Commission granted a number of commercial digital television station li-censes, including Station KNSV-TV, Phoenix, and KPHO-TV, Phoenix

Kompfner, Rudolf (1909-1977)AnAustrian archi-tect and engineer who worked in England as an ap-prentice architect in the mid-1930s where he invented

a split-beam oscilloscope tube Much of his physics background was self-taught, hands-on knowledge Following a World War II interment, Kompfuer was put to work on the development of a low-noise Klystron amplifier By 1943, he had invented a trav-eling-wave tube after which he became a scientific officer and Distinguished Scientist Following the war, he earned his doctorate at Oxford and went to work for Bell Laboratories, studying microwave tubes and continuing work on traveling-wave tubes

Fiber Optics Illustrated Dictionary

He became one of the lead workers on the historic

Echo satellite project

Kompfuer has received many engineering awards,

including the Duddell Medal and the Stuart Balantine

Medal of the Franklin Institute In 1973, he received

the IEEE Medal ofHonor for his contributions to

glo-bal communications technologies for his

develop-ment of the traveling-wave tube See Klystron,

trav-eling-wave tube

Konen Modem KouplerA battery-powered

com-mercial modem/modem adapter combination from

Unlimited Systems Konexx enables a modem to be

hooked into various types of phone lines and

cellu-lar phone systems while traveling

Kotel'nikov, Vladimir Aleksandrovich(1908- ) A

Russian contributor to fundamental research in

com-munication theory, and theory and practical research

in astrophysics He is especially well known for the

use of radio waves to locate and measure distances

to planetary bodies and for contributions to early

sat-ellite communications He is also remembered for

publishing "On the carrying capacity of 'ether' and

wire in electrical communication" (1933) that

de-scribes a theory of sampling and the representation

of a continuous signal from discrete samples His

theories were later supported by the work of Claude

Shannon Kotel'nikov served as V.P of the USSR

Academy of Sciences and chaired the Scientific

Council on radio astronomy While at the Institute of

Radioengineering and Electronics, he initiated

re-search in the submillimeter wave band See pulse

code modulation; sampling theorem; Shannon,

Claude

KPI See Key Performance Indicator

KQML See Knowledge Query and Manipulation

Language

Krum, Charles and HowardAnAmerican father

and son team who worked together in the early 1900s

to develop and patent a variety oftelegraph

transmit-ters and printing machines One of their early

suc-cesses was a printer created by interfacing a

modi-fied typewriter with a telegraph line, developed at the

end of 1908 With a mechanical apparatus ready to

use, it became necessary to develop some way to

syn-chronize the pulses and the printing For this, Howard

Crumb applied for a start-stop patent in 1910

krypton laserA type of gas laser which is primarily

krypton that can be used to produce intense red light,

or when used with certain optic enhancements,

sev-eral colors This is similar to an argon laser, except

that it produces a little less light; sometimes argon and krypton are combined Krypton lasers are

typi-cally water-cooled

Kurz, KarlInformation on this German experi-menter is scarce (he seems to be overshadowed by Barkhausen), but he apparently collaborated with Heinrich Barkhausen in discovering Barkhausen-Kurz oscillations See Barkhausen-Barkhausen-Kurz tube

KS See Kearney System

KTHKungliga Tekniska Hogskolan The Royal

In-stitute of Technology in Stockholm, Sweden The institution provides education in optical communica-tions within its photonics courses

KTI Key Telephone Interface

KTS 1 See key telephone system 2 See Kill the Spams

Ku-bandA range of microwave broadcast frequen-cies from approximately 11 to 14.5 GHzwhich is

fur-ther subdivided into fixed satellite service (FSS) and broadcasting satellite service (BSS) Ku-band is used primarily for data transmission, private networks, and news feeds Satellites transmitting Ku-band signals tend to be powerful enough for the receiving dish to

be small and convenient Uplinks are in the 14- to 14.5-GHz range and downlinks in the 11.7- to 12.2-GHz range

In November 2000, The Federal Communications Commission (FCC) extended permission to provid-ers of nongeostationary satellite services to operate

in certain segments of the Ku-band and issued rules and policies to govern their operations.Itwas felt that this would stimulate new competitive services such

as high-speed Internet access, telephony services, and media broadcasts It was further hoped that satellite transmission availability would increase services to rural areas The FCC determined that Multichannel Video Distribution and Data Services (MVDDSs) could operate in the 12.2- to 12.7-GHz frequencies without interfering with incumbent Broadcast Satel-lite Services (BSS) See band allocations for a chart See broadcasting satellite service, direct broadcast satellite, fixed satellite service

KV Bell Telephone jargon for key telephones (K=key, V=voice) The term was derived from the Universal Service Ordering Code (USOC) commonly used until the time ofthe AT&T divestiture in the mid-1980s

KVW Bell Telephone jargon for wall-mounted key telephones See KV

KWH See kilowatt-hour

used to symbolize wavelength, especially optical

wavelength

Lsymb inductance See inductance.

L CXRA backbone communications system based

upon L carrier coaxial technology developed in the

1930s in the U.S., known generically by the public

through warning signs as theTranscontinental Cable

system The system was intended for key government

communications and civil defense, interconnected

through facilities with underground repeaters, and

maintained by Bell telecommunications workers,

designed to transmit both telephone and television

signals

In the postwar years, the system was upgraded about

every 10 years The L-l system ofthe 1940s gave way

to an L-3 system by the 1950s and 1960s (L-2 was

used for a special installation between Washington,

D.C and Baltimore.) Later, through the use

ofrepeat-ers every couple of miles, 20-tube L-4 cable centofrepeat-ers

were established approximately every 150 miles By

the 1970s, L-5 circuits had been established The

ca-pacity of the system improved from a few MHz in

the 1940s to 57 MHz in the 1970s with voice

capaci-ties increasing from a few hundred voice channels to

more than 100,000

Following the Cold War, the repeater stations, which

resembled stone garden sheds over concrete vaults

every few miles along the cable route, were sold The

old physical infrastructure was gradually replaced

with fiber optic cables (with 20 times the capacity of

the L-5 system) and satellite links See L carrier

L carrierAn older, analog, frequency division

mul-tiplex (FDM), long-haul phone system that was

com-mon before digital services became prevalent

(met-ropolitan areas using FDM more commonly usedN

carriers).u.s.Department of Defense L carrier

com-munication systems in the post-World War II period

stretched in two main east-west links from

Washing-ton, D.C., west to California and south to the tip of

Florida, with many smaller trunk tributaries See L

CXR

L multiplexLMX Analog multiplexing circuits in

L carrier coaxial transmissions media

LSeries RecommendationsAseries oflTU-T

rec-ommended guidelines for construction, installation,

side plant telecommunications These guidelines may

be purchased from the ITV-T Since lTU-T specifi-cations and recommendations are widely followed by vendors in the telecommunications industry, those wanting to maximize interoperability with other sys-tems need to be aware of the information dissemi-nated by the ITU-T A full list of general categories

is listed in Appendix C and specific series topics are listed under individual entries in this dictionary, e.g.,

K Series Recommendations See L Series Recom-mendations chart

L systemSee L CXR

Ll cacheSee level 1 cache

L2 cacheSee level 2 cache

L1&L2Designations for the two radio frequencies (1227.6 and 1575.42 MHz) broadcast by Global Po-sitioning System (GPS) satellites See Global Posi-tioning System

L2F1 See Layer2Forwarding Protocol.2.Legacy

to the Future

L2TPSee Layer 2 Tunneling Protocol

L2TPextSee Layer2Tunneling Protocol extensions

L-bandA portion of the electromagnetic spectrum assigned for radio communications, ranging from 500

to 1500 MHz Within this range, the frequencies be-tween 950 and 1450 MHz are set aside for mobile communications Global Positioning Systems (GPSs) use the L-band frequencies, as do some of the planet probe systems See band allocations for chart

L-band, opticalIn optical communications, an lTU-specified transmission band in the 1565- to 1605-nm frequency range Until 2001, this spectrum was not widely supported

The development of better efficiency, high-density erbium doping in the early 1990s facilitated the de-velopment of practical L-band systems Benchtop erbium-doped fiber amplifiers (EDFA) may now be used with DWDM L-band networks (as they are for C-band), enabling optical amplification without hav-ing to convert optical signals to electrical and back again

In January 2001, Lucent Technologies announced it had completed the first installation of a C+L-band optical network for NTT Communications (Japan) This increased capacity by opening up the previously

Fiber Optics Illustrated Dictionary

ITU-TLSeriesReeommendations

Recommendation/Description

L.l Construction, installationand

protection of telecommunication

cal?les•• inpubliC; networks

L.2 ImpregnatioQofwoodenpoles

L.3 Armouring ofcables

L.4" AluminiumcabJe sheaths

L.5 Cable sheaths made of metals other

than leador aluminium

L.6 Methods·ofi-eeping cablesund~rgas

pressure

L.7 ApplicatiOtl()fjoint cllthodic

protection

L.8 Corrosion caused by alternating

current

L.9 Methodsoffenninating"metalUc

cable conductors

L.I0 Optical fiber cables for duct, tunnel,

aerial, and buried •application

L ll Joint use oftunnelsbypipelines and

telecommunication cables, and the

staridardizatjoD of underground duct

plans

L.12 Optical fiber'joints

L.l3 Sheath jointS<andorganiZersof

optical fiber cablesinthe outside

plant

L 14 Measuremenfmethodtodetermine

the tensile performance of optical

fiber cables under load

L.IS OpticallocaFdistribution networks

-factors tobe considered for their

construction

L 16 Collductive plastic material (CPM)

as protective covering for metal

cable sheaths

LJ 7 Implementation ofconnecting

customers into the public switched

telephone network (PSTN)via

opticalfib~rs

L.18 Sheathclosuresforterrestrialcopper

telecommunication cables

L.l9 Outside plant coppernetworks for

ISDN services

L.20 Creation of a fire secllrity code for

telecommunication facilities

L.21 Fire detection and alarm systems,

detector and sounder devices

L 22 Fire protection

Recommendation/Description

L 23 Fire extinction- classification and

location of fire extinguishing installations and equipment on premises

L.24 Classificationof outside plant waste L.25 Opticalfiber~ablenetwork

maintenance L.26 Optical fiber cables for aerial

application L.27 Method.fo17estimating.the

concentration of hydrogen in optical

fibercables L.28 EXffim.alad<iitional protection for

marinized terrestrial·cables L.29 As-laid report and maintenance/repair

logror marini:l;edterrestrial cable installation

Markers on marinized terrestrial cables

L.31 Optical fiberattenuators

L 32 Protection devices for through-cable

penetrations offrre-sector partitions L.33 Periodic control of fire extinction

devices in telecommunication buildings

L.34 InstallationofOpticalFibre Ground

Wire(OPGW) cable L.35 Installation of optical fiber cablesin

the access network L.36 Single mode fiber optic connectors L.37 Fiber optic (non-wavelength

selc;qtive)brapcbingdevices L.38 Use of trenchless techniques for the

construction of underground infrastructures for telecommunication cable installation

Investigation of the soil before using trenchless techniques

L.40 Optical tiber outside plant

maintenance support, monitoring and testing system

L.41 Maintenaqcewavelengthonfibers

carrying signals

L.44 Electric power supply for equipment installed;is outside plant

L.45 Minimizing the effect on the

environment from the outside plantin

telecommunicationnetworks L.46 Protection·oftelecommunication cables and plant from biological attack

L.47 Access facilities using hybrid fiber/ copper networks

was made possible by Lucent's new DWDM L-band

optical amplifier and dispersion-shifted fiber that is

more suited to carrying multiple wavelengths in the

L-band than in the C-band By the end of2001a

num-ber of leading optical firms were supplying L-band

components, such as dynamic gain equalizers that

could be configured by the customer for L- or C-band

ranges

Optical circulators optimized for DWDM L-band

applications typically come in two grades (A& B)

and feature low insertion loss, high isolation and

minimal distortion

LAASSee Local Area Augmentation System

label1 A symbol, or group of symbols, often

mne-monic, that identifies or describes an item, routine,

record, file, application, or process 2 In

program-ming, a reference point, usually for aprocedure,

func-tion, or subroutine The label may have a specific

meaning to the interpreter or compiler that processes

the code instructions or it may be a convenience for

the programmer for organizing code and simply be

ignored when the code is processed, depending upon

the environment 3.Innetworks, a convenient name

for a device to facilitate access For example, a printer

on a network known to the system as LZPTX5103,

may be assigned a label such as Building 3 Laser, to

make it easier for people to recognize 4.InATM and

Frame Relay networks, a short, fixed-length

identi-fier that facilitates packet/frame forwarding See

la-bel switching

label swappingIn label switching networks, a router

will commonly assign a new label to the received

transmission in preparation for forwarding it to the

next "hop" or leg in its journey toward the

destina-tion See label switching

label switchingIn ATM networks, a switching

mechanism intended to take advantage of the

flex-ibility and scalability of Internet Protocol (IP)

rout-ing Label switching combines some of the aspects

ofLayer 2 switching with Layer 3 routing, so the

dis-tinction between switching and routing is not as clear

as in other transmission schemes A label-switching

router can forward IP datagrams based upon a label

associated with the packet and will usually assign a

new label for the subsequent routing "hop" in the

connection See Multiprotocol Label Switching,

op-tical-label switching, tag switching

label-switched pathA network route that is

estab-lished based upon a label associated with a data

packet in a network, with a new label typically

as-signed dynamically for each subsequent hop in the

path (most routers do not spport static LSPs) The path

must be established before test data or

communica-tions data can be effectively routed through the LSP

A signaling protocol is typically used to set up paths

See label switching

labeled multiplexing Inintegrated services digital

networks (ISDN) and ATM networks, a routing

mechanism in which multiplexing is carried out by

concatenating blocks ofchannels with different

iden-tifiers in their labels

shortest path in network routing 2 A means of in-serting copy protection labels into data, such as com-pressed video data, so the information can be tagged,

or otherwise identified, and can only be written or read under prescribed circumstances This type of system is being developed to enable vendors to pro-vide digital services to home consumers without fear that the products will be widely pirated and redistrib-uted.Itis being experimentally applied to the design

of copy-protectable mass storage devices

Laboratory for Computer ScienceLCS An inter-departmental facility at the Massachusetts Institute

of Technology (MIT) engaged in computer science research and engineering LCS was founded in 1963 with support from the u.S Defense Department as a result of the launching of the Sputnik satellite

Members of the LCS have been involved in many important historical computer network developments including the ARPANET, Ethernet, Internet, and World Wide Web They have also been involved in research and development of encryption

technolo-~Pi~~~E~?=~~~~i:~~~~~Ci~:~~~~opment, and RSA Data Security LCS works coop- ' eratively with relevant departments and with the MIT

Artificial Intelligence Laboratory

LACLoop Assignment Center

LACESee Low-power Atmospheric Compensation Experiment

lacing cordA strong cord, sometimes coated or waxed, used to bundle wires strung along the same path

ladarlaser Doppler radar See Doppler, laser, radar

LADT See Local Area Data Transport

lagTo delay, linger, slacken, slow, be retarded, or tarry Lag occurs in computer applications when the speed of the system is unable to match the speed of the interaction of the user Lag is characteristic of dialup modem communications, where the speed of the data transmission doesn't match the speed of the computer processor Lag occurs on data networks when congestion occurs; that is, the number ofpack-ets may exceed the ability ofthe system to handle and transport them See cell rate, hysteresis, leaky bucket

LAGEOS IThe Laser Geodynamics Satellite, devel-oped and launched by the Marshall Space Flight Cen-ter in May 1976 LAGEOS was one of the earlier mote-sensing satellites used for Earth sciences re-search

Lakeside Programming GroupA collaboration of programming friends, which included Bill Gates, Paul Allen, and Ric Weiland The group created a payroll program in COBOL for a company in Port-land, Oregon They were informally named after the Lakeside private school attended by its members At the same time, the group had a programming contract

to build scheduling software for a school

Eventually Gates and Allen formed Traf-O-Data in the early 1970s, to create a traffic analysis program

The partnership that led to the formation of the

Fiber Optics Illustrated Dictionary

Microsoft Corporation See Gates, William; Allen,

Paul; Microsoft Corporation

LAISee Location Area Identity

LAM 1 line adapter module 2 See Lobe Attachment

Module

LAMA See Local Automatic Message Accounting

lamb dipInlaser technologies, a point in the

absorp-tion spectrum that dips (is lower in intensity) in

rela-tion to the overall absorprela-tion cross-secrela-tion (which is

generally Gaussian) When plotted, it graphically

re-sembles a small crater (there may be small

subsid-iary peaks within the overall transmittance dip) The

location ofthe lamb dip provides areference for

tran-sition frequencies that are Doppler-shift-free, which

is useful in certain laser spectroscopy applications

A lamb dip may be observed in laser operation or may

be generated by a sodium cell, for example, for

tun-ing and actively stabiliztun-ing a laser (e.g., a dye laser)

Passing a same-frequency probe beam through a

la-ser in the direction opposite the lala-ser pumping beam

reveals the transitional lamb dip pattern

lambda(symb - A)The 11th letter of the Greek

al-phabet, used as a symbol in a number of

mathemati-cal and logimathemati-cal contexts Lambda symbolizes the null

class, von Mangoldt's function, and wavelength

Lambda-Connect ProjectA Lawrence Livermore

ultracomputing development project funded by the

Laboratory Directed Research and Development

Pro-gram In recent years, the performance gap between

processing units and the links between the processors

has been widening This interesting project in

paral-lel multiprocessing seeks to narrow the gap by

over-coming the bottlenecksin transmitting data among

processors via traditional electronic connections

The LL team believes it can replace electron flow with

photon flow (light pulses of different wavelengths)

Speed improvements of up to 32 times are

consid-ered feasible The use of optical interconnects also

makes it practical to pack microprocessors in higher

densities which, presumably, also improves data

transport speeds and processing times

Ultracomputing projects are of particular interest to

strategic and scientific computing applications and

may be used by the U.S Department ofEnergy (DoE)

Accelerated Strategic Computing Initiative for

nuclear technologies simulations and testing and to

the Department ofDefense (DoD) for strategic

plan-ning and intelligence gathering and processing See

lambda switching, optical burst switching

lambda switchingAlso called wavelength

switch-ing, this is a technique used in high-speed optical

networks to switch individual optical wavelengths

into different paths to route data through the network

It is more akin to circuit switching than packet

switch-ing and can be implemented as end-to-end

connec-tions Fiber optic networks typically use lambdas

(wavelengths) in the near infrared spectrum,

trans-lating into frequencies ofaround 100 terahertz(THz).

In conjunction with multiplexing, which enables

many separate wavelengths to be transmitted along

a single fiber, lambda switching can be used to

cre-ate virtual circuits Qwest and other carriers began

to deploy lambda switching in their telecommunica-tions networks ca 2000 and 2001 See dense wave-length division multiplexing, Gilder's law, lambda, optical cross connect

lambdasphereThe environment within optical trans-missions paths that channels many wavelengths George Gilder is a speaker and well-known propo-nent of optically switched networks and is credited

with coining the term lambdasphere See Gilder's

law, lambda switching

lambert (symb - L) A centimeter-gram-second

(CGS) system unit ofluminance, equal to the bright-ness of an ideal diffusing surface that radiates or re-flects light at 1 lumen per square centimeter

Lambert's law, Lambert's cosine lawThe reflec-tion of radiant energy incident upon a small surface

in a particular direction is proportional to the cosine

of the angle between the reflected direction and the perpendicular (normal) of the surface

This relationship provides a means to calculate how much ofthe incident light (or sound) is reflected, as-suming the reflected light is constant in all directions

(essentially an ideal diffuser) and the angle ofinci-dence and associated angle ofreflectance are small.

Given these parameters, the perceived intensity ofthe light is independent of the angle at which the reflect-ing surface is viewed, but will vary accordreflect-ing to the angle of incidence at which the radiant energy en-counters the diffusing surface, as governed by Lambert's law Stated another way, the intensity of the incident light is relative to the angle ofincidence Body reflectance models follow Lambert's law Lambert's law was a prevailing relationship until the 1980s Then, the advent of graphics and acoustics modeling software and semiconductor-based instru-ments (e.g., goniometers) caused it to be more closely scrutinized for its generalizability for wider angles and different surfaces

In graphics, Lambert's law has been adjusted and generalized for smooth surfaces by L.B Wolff, thus overcoming some of the "small angle" limitations of Lambert's law In acoustics, Lambert's law's gener-alizability to diffusers was questioned, leading to the development and dissemination of diffusion cient data in much the same way absorption coeffi-cient data has been available See Bouguer's law, in-cidence angle

Lambertian reflectorA material that reflects light

in many directions (essentially an ideal reflector), thus diffusing it according to Lambert's law See Lambert's law

lameA colloquial term often used in programming

or electronics to derisively describe an uninspired or poor device, program, or solution to a problem The term is based upon the concept of limping along on one leg and thus not embodying positive qualities such as speed, efficiency, or grace Aperson who fre-quently comes up with weak or lame comments or solutions may be dubbed a "lamer."

lame delegationOn the Internet, a situation in which one or more authoritative domain name servers (DNS) that convert Internet Protocol (IP) addresses

the specified domain (which may have been called

by a system higher in the hierarchy) Lame

delega-tion occurs for a number of reasons:

Secondary servers, which are expected to

function as authoritative servers, may not

re-spond correctly If a secondary server is

un-specified, or not working correctly, the

situ-ation is lame in the sense that the second

"leg" isn't working properly Since

second-ary name servers are not mandated, only

rec-ommended, this is not an uncommon

occur-rence; most people associate this meaning

with the term

• The name server may respond incorrectly

from a cache rather than directly or may be

configured incorrectly

• There may be a lack ofcommunication

Ifus-ers change domain names, manage their own

IP numbers, or switch Web hosts without

co-ordinating with the name serving authority

and the ISP, all sorts of lame delegation

er-rors can occur

Lame delegations can result in email delays, lookup

slowdowns, and even a Web site "disappearing" from

the Internet (not being accessible) Ifthe primary and

secondary servers are on the same physical machine

and that machine goes down, there is no backup name

server and a lame delegation would be in effect until

the system came back online See domain name

server, lame

laminate n.A structure composed of layers, often

tightly sandwiched or bonded together Laminated

materials are often used in electronics, from early

voltaic piles, which sandwiched moistened

materi-als between layers ofmetal plates, to magnetic cores

and semiconductors, in which layers of various

ma-terials are combined according to their

electromag-netic properties.Anindividual layer in a laminated

structure is called aply.See semiconductor, thin film,

voltaic pile

Lamm, Heinrich(ca 1908- ) A German inventor

who studied medicine at the University of Munich,

Lamm was interested in creating an analogy to

in-sect vision using a bundle of optical fibers He

ac-quired fibers from the Rodenstock Optical Works and

painstakingly positioned the fibers to create a bundle

that could transmit an image for a short distance The

practical limitations deterred Lamm and a similar

concept had been patented already by Clarence W

Hansell who collaborated with television inventor

John L Baird, so Lamm ended up as a surgeon in

America rather than a well-known inventor of fiber

optics transmission systems See Hansell, Clarence;

Kapany, Narinder

lampAnilluminating device that converts energy into

light (usually visible light) In its basic form, a lamp

consists ofa light-producing source and a holder such

as a wick in an oil-holding vessel, bulb in a handheld,

battery-operated container (flashlight), fluorescent

bulb in a fluorescent receptacle, light-emitting diode

in a desk or floor stand

Lamps were used in some of the earliest communi-cations technologies By blocking the light from a lamp to signify dark or light, a binary communica-tions code could be devised to send signals over dis-tances A shutter made the process easier Shuttered lamps were used for many decades to send signals overland and among ships at sea

Lamps are also used as sources for photographic lighting, especially as "flash bulbs" to provide supple-mental illumination in low-light conditions Not all lamps emit light in the visible frequency ranges In-frared or ultraviolet light cannot be directly seen by humans, but the subjects illuminated may be seen with special equipment that translates the reflected light into visible frequencies or other forms ofenergy See Edison, Thomas A

LAMPSee Large Advanced Mirror Program

lampblackA sooty, dark carbon dust deposited by a smoking flame, as on the inside ofa glass lamp globe While its presence in lamps is usually undesirable, lampblack has commercial applications in the fabri-cation of some types of resistors

LANSee local area network

LAN adapterA hardware peripheral device or card that connects a computer to a local area network (LAN) Not all computers require LAN adapters; some come equipped with network cards and ports ready to attach to various connectors, commonly 1DBase-Tor 10Base-2 However, some require an in-termediary device between the network card and the network cable in the form of a LAN adapter

LAN awareApplications, systems, and devices that can recognize and appropriately respond to an inter-faced connection to a local area network (LAN) This usually involves communicating with other devices

on the net as security permits, locking and unlock-ing files as needed, queryunlock-ing appropriately, etc Some operating systems are designed to be LAN aware, others run with third-party software

LAN Channel StationLCS 1 In frame-based net-working, a channel protocol for LAN/mainframe in-tercommunications.In ffiM mainframe-related LCS, host applications define a consecutive pair of subchannels for channel reads/writes through TCP/IP LCS enables a local area network (LAN) MAC frame

to be transported and provides a command interface for activating/deactivating and querying LAN interfaces

2 A Bus-Tech commercial control unit emulation (also known as 8232) that provides a pass-through for exchanging data between a local area network! wide area network (LAN/WAN) and a mainframe through TCP/IP

LAN EmulationSee asynchronous transfer mode, LANE

LAN ManagerAnearly, commercial OS/2-based multiuser network operating system intended to run over TCP/IP or NetBEUI protocols Microsoft and 3Com's LAN Manager came in two versions: for MS-DOS, Microsoft Windows, and IBM'sOS/2,and for UnixlUNIX connections

Fiber Optics Illustrated Dictionary

LAN Protocols A catchall phrase for a wide variety

of protocols developed for local area computer

net-works, such as AppleTalk, Ethernet, TCPIIP, IPX, and

others

LAN segment In Frame Relay, a LAN linked to

an-other LAN using the same protocol through a bridge

See bridge, hop, router

LAN Server Acommercial multiuser network

oper-ating system from ffiM, based on OS/2 and NetBIOS

LAN Server supports a variety ofclient computer

op-erating systems, including OS/2, Microsoft DOS and

Windows, and Apple Macintosh It has been

super-seded by the OS/2 server version

LAN switch A local area network (LAN) switch, in

its simplest sense, is a stand-alone box with

connec-tions, which simply directs traffic along one or more

pathways However, with improved technology, LAN

switches are incorporating more and more intelligent

processing capabilities, and some are almost

indistin-guishable from routers Some are available as

modu-lar peripheral cards that fit into multiswitch card

chas-sis

LAN switches can help reduce or more efficiently

handle congestion and can improve response time on

networks They have the capability to redirect the

World Wide Web queries ofusers to local caches, and

reduce Internet queries and can help balance network

traffic among servers

LANCE Local Area Network Controller for Ethernet

Land, Edwin Herbert (1909-1991)AnAmerican

inventor who studied briefly at Harvard University,

Land is best known for his development ofpolarizers,

in the form of polarizing film sheets, in 1929.Itis

less well known that Land was a prolific inventor who

earned more than 500 patents in his lifetime, most of

them directly related to optics (especially

photogra-phy) He cofounded the Polaroid Corporation

(origi-nally the Land-Wheelwright Laboratories) with G

Wheelwright, in 1937, to develop and market his

in-ventions and demonstrated "instant" photography to

the Optical Society ofAmerica in 1947 He received

a patent for this historic photographic technology in

1951 (U.S #2,543,181)

In 1982, Land left the Polaroid Corporation but

con-tinued research on human visual perception

The Edwin H Land Medal was established by the

Optical Society of America (OSA) and the Society

for Imaging Science and Technology in his honor in

1992

Land attack, land.c A malicious software program

that became prevalent on the Internet in 1997, the

Land attack was similar to an earlier SYN attack

pro-gram Land was programmed to attack systems

us-ing Internet Protocol (IF) communications by

inter-fering with the stack Certain routers were also

vul-nerable Abroad segment of operating systems from

Apple, Cisco, Microsoft, and Sun and several BSD

systems were found to be vulnerable Some machines

crashed while others hung or experienced slowdowns,

depending upon how robust the operating system was

and whether it could still function while one aspect

of it was caught in an endless loop through spoofing

that tricked the system into calling itself A more Microsoft-aggressive version called latierra.c was later released on hacker sites Vendors posted patches

to reduce or remove the vulnerability and updated subsequent releases of software to reflect these changes See Denial of Service attack, Trojan horse, virus

land/groove recording, land and groove recording

A high-density recording technology for magneto-optical media DVD disc surfaces are divided into annular zones, keeping the length ofa sector and the recording density mostly constant through the disc The zones are divided into two types of tracks: land tracks and groove tracks These tracks, inturn,are divided into sectors The hierarchical division into smaller units is similar to the storage and access for-mats used on hard disks, with adaptations to fit the nature ofoptical disks Data are recorded on the land (the higher surface) and the groove (the indented sur-face), while address information is encoded in the pits Permanent data that are readable but not writ-able by the user are kept separate from the user re-cording fields See wobbled groove, wobbled land groove

LANDA Local Area Network Dealers' Association This is now called NetPros by LANDA The organi-zation promotes and supports excellence among Ca-nadian resellers, consultants, and systems integrators

in the information technology (IT) industries http://www.netpros.ca/

landline, land-line, land line Communications cir-cuits, especially telegraph and telephone, which travel through terrestrial wires and stations Many mobile units interface with landlines, so that even if a call originates as a wireless call, it may be completed as

a landline call to extend distance and free up wire-less channels

Landsat A series of satellites first launched through federal funding in the mid-1960s for remote sensing

of the Earth from space

The Landsat Earth sensing system launches were ini-tiated in 1966 as a response to the announcement of plans for launching civilian Earth Resources Obser-vations Satellites (EROS) As a result, NASA began

to plan a satellite launch in order to secure informa-tion on Earth resources and provide for nainforma-tional se-curity provisions in space

This led to the launch of the Earth Resources Tech-nology Satellite (ERTS-l) in 1972, with similar sat-ellites launched in 1975 and 1978 The program was renamed Landsat in 1975 Landsats 4and 5 were launched in the early 1980s, and jurisdiction was transferred to the U.S National Oceanographic and Atmospheric Administration (NOAA)

In 1986, during the Reagan administration, jurisdiction was changed to a commercial company, EOSAT, and the primary users became large institu-tions that could afford expensive satellite data Com-plete archiving of data was not always undertaken EOSAT designed and built Landsat 6, which failed

on launch

In 1992, legislation was passed to return future

Land-ofNASA's Mission to Planet Earth program in 1994.

Planning began for the Landsat 7 project

Landsat satellites are in near-polar orbits, designed

to be sun synchronous; that is, the satellites cross the

equator at the same local sun time in each orbit Thus,

lighting conditions are kept uniform The satellites

are equipped with telemetry and remote sensing

equipment, including cameras and multispectral

scan-ners

Data collected from early Landsat projects were

stored in X-format, that is, band-interleaved by pixel

pair (BIP-2) This format was superseded by EDIPS

(EROS Digital Image Processing System) with a

resolution of3596 pixels x 2983 scanlines, in

band-sequential (BSQ) or band-interleaved-by-line (BIL)

formats

LANE LAN Emulation Local area network (LAN)

emulation services and protocols running over

asyn-chronous transfer mode networks See asynasyn-chronous

transfer mode and the appendix for greater detail

languageIn computer programming, a means

ofrep-resenting instructions, procedures, functions, anddata

through symbols and syntax which can be interpreted

into machine instructions to control the computer

Common high- and medium-level programming,

scripting, and page description languages include

Perl, Java, C, C++, PostScript, LISP, Pascal, BASIC,

Cobol, and FORTRAN Acommon markup language

used on the Web is HTML There are also job

con-trollanguages, description languages, graphics

guages, and low-level assembly and machine

lan-guages

Language of Temporal Ordering Specification

LOTOS A language for the formal process and

al-gebraic specification of computer network protocols

for concurrent and distributed networks, described as

ISO 8807-1990 LOTOS has been used

internation-ally to specify many systems, especiinternation-ally by

univer-sity groups LOTOS is applicable to the specification

ofOpen Systems Interconnect (OSI) model systems,

for example

Lankard, John R.In collaboration with Peter P

Sorokin, Lankard described tunable organic dye

la-sers in the IBM Journal ofResearch and

Develop-mentin 1966 at about the same time dye laser

tech-nology was being developed by Schmidt et al in

Germany

Lankard continued to study lasers over the subsequent

decades, coauthoring articles on organic dye lasers

in the 1960s, Q switches in the 1970s and laser

ap-plications in the 1980s and 1990s, such as laser

etch-ing and thin film packagetch-ing See laser history;

Sorokin, Peter P

LANNET1 large artificial neuron network 2

Asub-sidiary company ofMadge Networks, N.V., and

lead-ing supplier of next-generation Ethernet and ATM

switching technologies for local area networks

(LANs) LANNET was acquired by Lucent

Tech-nologies in 1998

LANtasticA commercial peer-to-peer

NetBIOS-based network operating system from Artisoft It

sup-including Microsoft DOS and Windows, ffiM's OS/

2, Apple's Macintosh, and various Unix clients

lapAdevice used for grinding piezoelectric crystals Since the resonance frequencies of crystals are due

in part to their size and shape, the lap provides a means to fine-tune the crystal See detector, piezo-electric, quartz, Y cut

LAP 1 link access procedure 2 See Link Access Protocol

laplaciometerAnearly analog calculator designed for complex mathematical work by J Atanasoff and some of his graduate students in the 1930s The laplaciometer was used to analyze the geometry of surfaces These developments led to the design and creation of the historic Atanasoff-Berry Computer (ABC) See Atanasoff-Berry Computer

LaplinkApopular, practical commercial hardware/ software networking utility introduced in 1986 for transferring files between computers, especially be-tween laptop computers and office workstations It

is very common for mobile computer users to want

to transfer the information from their laptops to their desk computers, and sometimes to transfer in the other direction as well (e.g., sales leads) Laptops typically have smaller hard drives and higher secu-rity risks than desktop computers, making it advis-able to regularly move the data offthe laptop Trans-fers can be achieved in a number ofways, through a serial port, over a parallel connection, or through phone lines In 1995 LapLink Host was added to the product line to provide technical support to remote workers

Laplink was developed by Traveling Software, Inc.,

a Washington State company devoted to supporting the needs of mobile users, founded in 1982 by Mark Eppley

lappingAtechnique for wrapping electrical tape, foil,

or other ribbons around a central core so that the next edge overlaps the previous one, in order to create close contact and a good seal

lapping filmAfinely abrasive polyster substrate sold

in color-coded sheets according to grade.Itis com-mercially available in a variety of minerals, micron grades, and backings The film may be in resealable bags to preserve its properties and prevent contami-nation by moisture and solid particles It is available

in different shapes for manual or machine polishing applications Successive grades allow finer and finer polishing, similar to the process ofusing finer grades

of sandpaper to finish a wood product Plain and ad-hesive backings are available Aluminum oxide, sili-con carbide, and cerium oxide lapping films are used for a variety of types of surfaces Diamond lapping films are suitable for harder surfaces such as metals Diamond lapping film is available in several styles: fine or course diamond particles can be bonded di-rectly to film backing or the diamond particles can

be encapsulated within a soft ceramic coating which

is then bonded to the film

Lapping film may be used to polish fiber filament ferrules, magnetic media, oxide and thin film disks,