`
`WHAT EVERY ENGINEER SHOULD KNOW ABOUT
`
`
`Lasers
`
`D. C. WINBURN
`
`log Ala/no.5; New Mexico
`
`
`
`MARCEL DEKKER, INC.
`
`New York and Basel
`
`IPR2017-021 12, Hamamatsu V. SEMICAPS
`
`SEMICAPS Ex. 2012 - 001
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`IPR2017-02112, Hamamatsu v. SEMICAPS
`SEMICAPS Ex. 2012 - 001
`
`

`

`
`
`Library of Congress Catalogingwin-Publication Data
`
`Winburn, D. C.
`What every engineer should know about lasers.
`
`Includes index.
`1. Lasers.
`I. Title.
`TA1675.W56
`1987'
`
`~g,ISBN 0-8247-7748-4
`
`621.36’6
`
`87-5279
`
`COPYRIGHT ©1987 by MARCEL DEKKER, INC. All Rights Reserved
`
`Neither this book nor any part may be reproduced or transmitted in
`any form or by any means, electronic or mechanical, including photo-
`copying, microfilming, and recording, or by any information storage
`and retrieval system, without permission in writing from the publisher.
`
`MARCEL DEKKER, INC.
`270 Madison Avenue, New York, New York 10016
`
`Current printing (last digit) :
`10 9 8 7 6 5 4 3 2 l
`
`PRINTED IN THE UNITED STATES OF AMERICA
`i-
`
`‘
`
`IPR2017-02112, Hamamatsu V. SEMICAPS
`
`SEMICAPS Ex. 2012 - 002
`
`IPR2017-02112, Hamamatsu v. SEMICAPS
`SEMICAPS Ex. 2012 - 002
`
`

`

` '5
`
`PULSED LASER BEAM TRAITS
`
`35
`
`provide CW outputs because the gas can be engineered to flow through the lasing
`chamber not only to replenish the gas but also to provide cooling resulting from
`the excitation method, usually xenon lamps. CW lasers often require long periods
`of time (several minutes, or even hours) to stabilize the beam’s intensity for very
`constant output. Essentially all alignment lasers are CW of low intensity emitting
`i in the visual color range to be easily sighted.
`In determining whether a laser beam is CW or pulsed, the American National
`Standards Institute, in the ANSI 2136.1 “Safe Use of Lasers” standard, defines
`a continuous wave as “The output of a laser which is operated in a continuous
`rather than a pulsed mode In this standard, a laser operating with a continuous
`output for a period >0.25 s is regarded as a CW laser.”
`.
`The intensity of a CW laser beamis measured'in the unit, watts per square i
`centimeter (W/crn2 ). This unit is often referred to as ‘power density” rather thanI-
`the technical term irradiance, used by physicists and defined in ANSI 2,136.1 as r
`the “Quotient of the radiant flux incident on an element of the surface contain- v
`ing the point at which irradiance is measured, (divided) by the area of that ele- (
`ment. Unit: watt(s) per square centimeter,W-cm" 2 .” In this work, the term power i
`density and the unit W/cm2 will be used to describe the intensity of a CW beam.
`1’
`-J
`
`PULSED LASER BEAM TRAITS
`
`The definitiori of a pulsed laser in this book will be that used in ANSI 2136.1, “A
`laser that delivers its energy in the form of a single'puise or a train of pulses. in
`this standard, the duration of a pulse (is) <0.25 5.” The term “energy density”
`wili be used to describe the intensity of a pulsed laser beam in terms of joules per
`square centimeter (Ifcmz). The ANSI 2136.1 standard defines a pulsed beamis
`intensity as “radiant exposure” and states it thusly: “Surface density of the ra-
`diant energy received. Unit: joules per centimeter squared (J ocm“2)”.
`The relationship of joules (energy) to watts (pewer) is:
`
`J = W X time (one second), one watt-second,
`J
`W = _—-———, onejoule per second;
`tlme (one second)
`
`or
`
`thus fast-pulsed laser users can claim that the power (W) used by entire cities Can
`be contained in one pulse of their laser. For example, in laser fusion research (in—
`ertial confinement experiments), if a laser is pulsed for one nanosecond, 10—9
`sec, and contains 40 kJ energy, the power calculation would yield:
`J
`40,0001
`w:# =——=4.><1o4><109
`
`= 4 x 1013 watts, or 40 Tarawattsll
`
`IPR2017-02112, Hamamatsu V. SEMICAPS
`
`SEMICAPS Ex. 2012 - 003
`
`IPR2017-02112, Hamamatsu v. SEMICAPS
`SEMICAPS Ex. 2012 - 003
`
`