Edmund Optics(cid:15)(cid:3)(cid:44)(cid:81)(cid:70)(cid:17)(cid:3)
`(cid:40)(cid:91)(cid:75)(cid:76)(cid:69)(cid:76)(cid:87)(cid:3)(cid:20)(cid:19)10(cid:3)
`
`0001
`
`

`
`ELSEVIER SCIENCE B.V.
`
`Sara Burgerhartstraat 25
`P.O. Box 211, 1000 AE Amsterdam, The Netherlands
`
`First edition 1984
`
`Second impression 1985
`Third impression 1987
`Fourth impression 1996
`
`ISBN: 0-444-42360-5 (Vol. 6) (hardcoveri
`ISBN: 0-444-42834-8 (Vol. 6) (paperback)
`ISBN: 0-444-41903-9 (Series)
`
`© Elsevier Science B.V., 1984
`All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted
`in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior
`written permission of the publisher, Elsevier Science B.V., P.O. Box 521, 1000 AM Amsterdam, The Netherlands.
`
`Special regulations for readers in the USA. This publication has been registered with the Copyright Clearance
`Center Inc. (CCC), 222 Rosewood Drive Danvers, MA 01923. Information can be obtained from the CCC about
`conditions under which photocopies of parts of this publication may be made in the U.S.A. All other copyright
`questions, including photocopying outside of the USA, should be referred to the copyright owner, Elsevier
`Science B.V., unless otherwise specified.
`
`No responsibility is assumed by the publisher for any injury and/or damage to persons or property as a matter
`of products liability, negligence or otherwise, or from any use or operation of any methods, products, instruc-
`tions or ideas contained in the material herein.
`
`This book is printed on acid-free paper.
`
`Transferred to digital printing 2006 ‘
`
`.
`
`7'
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`
`
`0002
`
`

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`xiii
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`v
`vii
`ix
`xi
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`1
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`5
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`7
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`I
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`TABLE OF CONTENTS
`
`I
`I
`I
`I
`I
`I
`DEDICATION I
`I
`I
`I
`I
`I
`I
`FOREWORD I
`I
`I
`I
`I
`I
`I
`PREFACE I
`I
`AUTHOR'S PREFACE I
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`I
`I
`I
`I
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`I
`I
`I
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`I
`I
`I
`I
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`I
`I
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`I
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`I
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`I
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`Chapter 1
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`INTRODUCTION AND HISTORY I
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`References I
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`I
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`I
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`I
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`I
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`I
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`I
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`I
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`I
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`I II
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`I.
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`I
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`I
`I
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`II
`
`Chapter 2
`
`COMPOSITION, STRUCTURE AND PROPERTIES OF
`INORGANIC AND ORGANIC GLASSES
`
`KJ\J>bJl\):--
`
`I"I"!"!"‘\’!"“""
`
`I
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`I
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`I
`I
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`I
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`I
`I
`I
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`I
`I
`I
`I
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`I
`I
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`I
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`I
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`Glass-Forming Inorganic Materials I
`Crystallite Theory I
`I
`I
`I
`I
`I
`I
`I
`I
`I
`I
`Random Network TheoryI I
`I
`I
`I
`I
`I
`Phase Separation, Devitrification I
`I
`I
`I
`I
`I
`I
`Glass Forming Organic Materials I
`Crystalline and Amorphous Behaviour of Polymers I
`Thermal Behaviour oflnorganic and Organic Glasses
`Mechanical Properties oflnorganic Glasses I
`I
`Chemical Properties oflnorganic and Organic Glasses
`Electrical Properties. I
`I
`I
`I
`I
`I
`I
`I
`I
`I
`I
`I
`I
`I
`I
`I
`Optical Properties I
`I
`I
`I
`I
`I
`Materials Transparent in Ultraviolet and Infrared
`Photochromic Glasses
`I
`I
`I
`I
`I
`I
`I
`I
`I
`Glass Ceramics
`II
`I
`II
`References I
`I
`I
`I
`I
`l
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`I
`I
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`I
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`I
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`I
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`I
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`I
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`I
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`NATURE OF A SURFACE
`
`I
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`I
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`I
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`7
`8
`9
`10
`l
`l
`I2
`12
`I5
`15
`17
`19
`21
`24
`27
`32
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`34
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`34
`35
`36
`38
`39
`41
`44
`44
`45
`46
`49
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`I
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`Characterization ofa Surface I
`I
`Structure ofa Surface I
`I
`I
`I
`I
`I
`I
`Chemical Composition ofa Surface
`Energy ofa Surface I
`I
`I
`I
`I
`I
`I
`I
`I
`I
`I
`I
`Morphology ofa Surface. I
`I
`I
`I
`I
`Interactions Solid/Gas and Solid/Solid
`Production of Glass Surface
`I
`I
`I
`Drawing and Casting I
`I
`I
`Pressing and Moulding I
`Grinding and PolishingI I
`References I
`I
`I
`I
`I
`I
`I
`I
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`I
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`0003
`
`

`
`xiv
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`Chapter 4
`
`CLEANING oF SUBSTRATE SURFACES .
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`la;'~’:‘;.gs;r2;.;_.a.,32:;.2g...;.-r.
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`-BUJIN)-‘
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`‘ON-UI:J>-.La.).l\);—-:-L-L—L.
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`:“:“:'=-.‘>:'>:“:‘>:".4>:'*‘.“:'>4>V.;)fi)n—-—-I-—n—-n—In-4n—n-un—In—:—u
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`Cleaning Procedures .
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`Cleaning with Solvents .
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`Rubbing and Immersion Cleaning .
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`Vapour Degreasing .
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`Ultrasonic Cleaning .
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`Spray Cleaning .
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`Cleaning by Heating and Irradiation .
`Cleaning by Stripping Lacquer Coatings .
`Cleaning in an Electrical Discharge .
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`Cleaning Cycles .
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`Cleaning of Organic Glass .
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`Methods to Control Surface Cleanliness
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`Maintenance of Clean Surfaces .
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`Chapter 5
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`GLASS AND THIN FILMS .
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`5.1
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`5.2
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`5.2.1.1
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`5.2.1.2
`5.2.2
`5.2.2.1
`5.2.2.2
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`5.2.3
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`.°‘.°‘.°‘S3‘.°‘F".°‘.°‘.°‘.°‘
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`t~.)t~)t~JI\)t\J_I\)t~)_-—_-—_-—.....~N__
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`64
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`Correlation between Glass and Thin Films .
`Adhesion between Substrate and Film .
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`Methods of Adhesion Measurement
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`Parameter Influencing Adhesion .
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`Coating and Substrate Materials .
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`Influence of the Coating Method .
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`Aging .
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`Practical Aspects of Adhesion Measurement
`Scotch Tape Test .
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`Final Comments to Adhesion .
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`5.2.3.2
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`5.2.3.4
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`5.2.4
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`5.2.4.1
`5.2.4.2
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`5.2.4.3
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`5.2.5
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`Chapter 6
`
`FILM FORMATION METHODS.
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`.°‘.°‘ iii
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`Subtractive Methods
`Chemical Processes .
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`s~»~—-
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`6.2.1.4. l .l
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`6.2. l .4. l .2
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`6.2.1.4. l .2.l
`6.2. 1.4.1 .2.2
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`6.2. l .4. 1 .3
`6.2.l.4.2
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`6.2. 1 .4.2.l
`6.2.l.4.2.2
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`6.2.l.5.2.l
`6.2.l.5.2.2
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`6.2.l.5.2.3
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`6.2.l.5.2.4
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`6.2.l.5.2.5
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`6.2.l.5.2.6
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`6.2.l.5.2.7
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`6.2.l.5.2.8
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`Formation, Structure, Optical and Mechanical Properties .
`Coating Procedure .
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`Deposition of Organic Films from Solutions .
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`Chemical Vapour Deposition at Low Temperatures .
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`Atmospheric Pressure and Low Pressure CVD .
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`Spray Coating _
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`Atmospheric Pressure CVD .
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`Compound Films .
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`Metal Films .
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`Low Pressure CVD .
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`Plasma Activated and Photon Activated CVD .
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`Plasma Activated CVD .
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`Photon Activated CVD .
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`Physical Vapour Deposition .
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`Vacuum Technology .
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`Vacuum Pumps .
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`Mechanical Displacement Pumps .
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`Diffusion Pumps .
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`Molecular Pumps .
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`Cryo Pumps .
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`High Vacuum Process Systems .
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`Film Deposition by Evaporation and Condensation in High
`Vacuum .
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`Evaporation .
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`Energy, Velocity and Directional Distribution of the
`Vapour Atoms and Thickness Uniformity of the Films
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`Efficiency of Energy and Mass
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`Evaporation Techniques .
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`Transit of the Vapourized Species Through the Reduced
`Atmosphere .
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`Condensation and Film Formation .
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`Evaporation Materials .
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`Evaporation Plants .
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`Film Deposition by Cathode Sputtering .
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`General Considerations .
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`Sputtering Threshold and Sputtering Yield .
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`XV
`
`92
`93
`93
`94
`94
`94
`96
`96
`96
`109
`ll4
`115
`1 l7
`120
`120
`125
`127
`130
`134
`135
`I35
`139
`140
`141
`145
`l45
`l49
`152
`156
`158
`
`169
`l70
`
`l74
`189
`191
`
`198
`199
`203
`207
`213
`215
`218
`
`14
`Jl
`
`
`
`0005
`
`

`
`xvi
`
`6.2.l.5.3.3
`6.2.1.5.3.4
`6.2.l.5.3.5
`6.2.l.5.3.6
`6.2.l.5.3.7
`6.2.l.5.3.8
`6.2.1.5.3.9
`6.2.l.5.3.l0
`6.2.1.5.3.1l
`6.2.l.5.3.l2
`6.2.1.5.3.l3
`6.2.1.5.3.14
`6.2.l.5.4
`6.2.1.5.4.1
`6.2.l.5.4.2
`6.2.1.5.4.3
`6.2.l.5.5
`6.2.1.5.5.1
`6.2.l.5.5.2
`6.2.1.5.5.3
`6.2.1.5.5.4
`6.2.l.5.5.5
`6.2.l.5.6
`
`4
`
`4
`
`4
`
`4
`
`4
`4
`
`4
`
`Ejection ofother Particles and Emission of Radiation
`4
`Ion Implantation 4
`4
`4
`4
`4
`4
`4
`4
`.
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`Alterations in Surface Films, Diffusion and Dissociation
`Sputtering Rate 4
`.
`4
`.
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`Particles Velocity and Energy 4
`.
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`Angular Distribution 4
`4
`4
`.
`4
`4
`4
`4
`4
`4
`4
`4
`4
`Composition ofthe Sputtered Material
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`The Gas Discharge. 4
`4
`4
`4
`4
`4
`4
`4
`4
`Thickness Uniformity and Mass Efficiency in Sputtering 4
`Sputtering Materials .
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`.
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`Sputtering Plants 4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4‘ 4
`4
`4
`4
`4
`Comparison Evaporation — Sputtering
`Film Deposition by Ion Plating.
`4
`4
`4
`Characteristics oflon Plating 4
`4
`4
`Advantages oflon Plating. 4
`4
`4
`4
`4
`Applications oflon Plating 4
`4
`4
`Reactive Deposition Processes 4
`General Considerations
`4
`4
`4
`4
`Reactive Evaporation 4
`4
`Activated Reactive Evaporation
`Reactive Sputtering 4
`4
`4
`4
`Reactive lon Plating 4
`.
`4
`4
`Plasma Polymerization
`References 4
`4
`4
`4
`4
`
`4
`4
`
`4
`4
`4
`
`4
`4
`
`4
`4
`4
`
`4
`
`4
`4
`
`4
`
`4
`
`4
`4
`4
`
`4
`4
`
`4
`
`4
`4
`
`4
`4
`4
`4
`4
`4
`4
`.
`
`4
`
`4
`4
`4
`
`4
`
`4
`4
`
`223
`224
`224
`225
`226
`226
`227
`228
`239
`242
`244
`246
`247
`248
`250
`253
`256
`256
`258
`262
`268
`269
`270
`275
`
`8-3.1
`8.3.2
`8.4
`8.4.1
`8.4.2
`8.4.3
`8.5
`8.6
`8.7
`
`Chapter
`
`9.1
`9.2
`9.3
`9.3.1
`9.3.2
`9.3.3
`9.3.4
`9.3.5
`9.3.6
`9.4
`
`4
`
`.
`
`4
`4
`4
`
`4
`4
`
`4
`
`4
`4
`
`4
`
`4
`
`4
`
`4
`4
`4
`4
`
`4
`4
`
`4
`
`4
`
`4
`
`4
`
`4
`
`4
`4
`4
`
`4
`
`4
`4
`4
`
`4
`4
`4
`
`4
`4
`
`4
`4
`
`4
`
`4
`
`4
`4
`4
`
`4
`
`4
`
`4
`4
`4
`4
`4
`4
`
`4
`
`4
`4
`4
`
`4
`
`4
`4
`4
`4
`
`4
`
`4
`
`4
`4
`
`4
`
`4
`
`4
`4
`
`4
`
`_
`4
`
`4
`4
`
`4
`
`4
`
`4
`
`4
`
`4
`
`4
`
`4
`4
`4
`
`4
`
`4
`
`4
`
`4
`
`4
`4
`4
`
`4
`
`4
`
`Chapter 7
`
`FILM THICKNESS4
`
`4
`
`4
`
`4
`
`4
`
`4
`
`4
`
`4
`
`4
`
`4
`
`4
`
`4
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`4
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`4
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`4
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`4
`
`4
`
`4
`
`4
`
`4
`
`4
`
`4
`
`4
`
`4
`4
`4
`4
`4
`4
`4
`4
`General Considerations
`4
`4
`Methods Applicable to all Types ofFilms 4
`4
`4
`Interference Methods .
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`4
`Stylus Methods
`4
`4
`.
`4
`4
`4
`4
`4
`4
`4
`4
`4
`.
`4
`4
`4
`Methods Applicable to PVD Films 4
`Optical Reflectance and Transmittance Measurements
`Oscillating Quartz Crystal Microbalance 4
`4
`4
`4
`4
`4
`4
`Vapour Density Measurement by Mass Spectrometry 4
`Trendsin Monitoring Technology
`4
`4
`4
`4
`4
`4
`References 4
`4
`4
`4
`4
`.
`4
`4
`4
`4
`4
`
`4
`
`4
`
`4
`
`4
`
`4
`4
`
`4
`
`4
`4
`
`4
`
`4
`
`4
`
`4
`
`4
`
`4
`
`7.1
`7.2
`7.2.1
`7.2.2
`7.3
`7.3.1
`7.3.2
`7.3.3
`7.4
`
`Chapter 8
`8.1
`.
`8.3
`
`4
`
`4
`
`4
`4
`4
`4
`4
`4
`4
`
`4
`4
`4
`
`4
`
`4
`4
`
`4
`4
`
`4
`4
`4
`
`4
`
`4
`
`4
`
`4
`
`4
`
`4
`
`4
`.
`4
`
`287
`
`287
`291
`291
`292
`293
`293
`297
`304
`306
`308
`
`341
`311
`322
`
`4
`
`A
`
`_
`
`9.4.1
`
`9.4.2
`9.4.3
`
`9.4.4
`9.4.5
`9.4.6
`9.4.7
`9.4.8
`9.5
`9.5-1
`9-5-2
`95-2-1
`9-5-2-2
`9.6
`
`9.6.1
`
`9-6-4
`9-7
`
`PROPERTIES or THIN FILMS 4
`Structure 4
`4
`4
`4
`4
`4
`4
`4
`4
`.
`4
`4
`Microstructure 4
`4
`4
`4
`4
`4
`Chemical Composition. 4
`
`4
`4
`
`4
`4
`4
`
`4
`4
`4
`
`4
`4
`4
`
`4
`44
`
`4
`4
`4
`
`.
`
`4
`4
`4
`
`4
`4
`4
`
`4
`
`4
`
`4
`
`4
`4
`
`.
`4
`
`4
`4
`
`4
`
`4
`
`i
`
`0006
`
`

`
`223
`
`224
`224
`225
`
`226
`
`226
`227
`
`228
`
`239
`242
`
`244
`
`246
`
`247
`
`248
`250
`
`253
`
`256
`256
`
`258
`262
`268
`
`269
`
`270
`275
`
`287
`
`287
`291
`291
`
`292
`
`8.3.1
`
`8.3.2
`8.4
`
`8.4.1
`8.4.2
`
`8.4.3
`
`8.5
`
`8.6
`
`8.7
`
`Surface Analysis
`.
`Depth Profiling
`Mechanical Properties .
`Stress.
`.
`.
`.
`
`Hardness and Abrasion
`
`Density.....
`Chemical and Environmental Stability .
`Optical Properties ofThin Films .
`.
`Electro—Optical Materials and their Properties
`References
`
`Chapter 9
`
`APPLICATION OF COATINGS ON GLASS
`
`9.1
`
`9.2
`
`9.3
`
`9.3.1
`
`9.3.2
`9.3.3
`9.3.4
`9.3.5
`
`9.3.6
`9.4
`
`9.4.1
`
`9.4.2
`9.4.3
`
`9.4.4
`9.4.5
`9.4.6
`
`General Considerations
`
`.
`
`Calculation ofOptical Film Systems
`Antireflective Coatings .
`.
`.
`.
`Single Layer Antirellection Coatings
`Double Layer Antireflection Coatings .
`.
`Multilayer Antireflection Coatings
`.
`Antireflection Coatings at Oblique Incidence .
`Inhomogeneous Antireflection Coatings .
`.
`Applications ofAntireflection Coatings.
`.
`Rear Surface Mirrors, Surface Mirrors and Beam S
`Mirrors .
`.
`.
`.
`.
`.
`.
`
`plitter
`
`RearSurface Mirrors .
`
`..
`
`Metal Film Surface Mirrors
`
`Beam Splitter Mirrors
`Neutral Density Filters
`Dielectric Mirrors
`
`.
`
`.
`
`.
`
`.
`
`.
`
`.
`
`.
`
`.
`
`.
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`.
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`.
`
`.
`
`.
`
`xvii
`
`332
`
`335
`
`341
`342
`353
`356
`
`357
`
`359
`381
`
`384
`
`391
`
`391
`395
`
`399
`399
`401
`
`402
`
`405
`
`406
`406
`
`407
`409
`
`409
`414
`
`419
`419
`421
`
`
`
`
`
`
`
`
`
`zcééxéc~a%'-‘.14:.....:.'r;‘:.~:,;.<-i~".:»~;:.;.~:4-’:;_:‘;.;.:3';,~;.,‘->‘;-:.r'~.~«-;-v,~~»-;;~_«-W,~
`
`
`
`
`
`
`
`
`
`j
`
`9.4.7
`9.4.8
`9.5
`9.5.1
`9.5.2
`
`9.5.2.1
`
`9.5.2.2
`
`9.6
`9.6.1
`
`9.6.2
`
`9.6.3
`
`9.6.4
`9.7
`
`9.8
`
`Cold Light Mirrors and Heat Mirrors
`Laser C oatings
`Artificial Jewels .
`
`.
`
`.
`Separation ofLight by Filters .
`Low- and High-Pass Edge Filters
`Band Pass Interference Filters
`
`Narrow-Band Filters
`
`Broad—Band Filters .
`
`.
`
`.
`Absorptive Films .
`Eye Protection Films .
`Photo Masks .
`.
`
`.
`.
`
`.
`
`Scales, Reticles, Apertures
`Phase Plates .
`.
`.
`.
`.
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`.
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`.
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`.
`.
`
`.
`
`.
`
`.
`
`.
`
`.
`
`.
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`.
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`.
`
`Transparent Conductive Coatings .
`Energy Related Coatings .
`.
`.
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`
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`.
`
`424
`427
`428
`428
`
`433
`
`433
`436
`
`437
`
`437
`
`438
`
`440
`
`440
`441
`444
`
`%5
`
`3i
`
`1
`
`293
`293
`
`297
`304
`
`306
`
`308
`
`341
`
`311
`
`322
`
`332
`
`0007
`
`

`
`.
`.
`.
`.
`.
`.
`.
`.
`Solderable Coatings .
`.
`.
`.
`.
`.
`.
`.
`.
`Integrated Optics .
`.
`.
`Integrated Optics Components .
`Present Status and Trend .
`.
`.
`.
`.
`Scientific Applications .
`.
`.
`.
`t
`.
`References .
`.
`.
`.
`.
`.
`.
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`.
`.
`.
`.
`.
`
`445
`.
`445
`.
`. 447
`.
`451
`.
`454
`
`AUTHOR INDEX
`
`
`
`:_M,,,i..,.g~;~—-,-pp».-,,-1~,.~:.s»,«;,~.wVW.‘-.,,.,.,,V
`
`9%
`
`s
`
`0008
`
`

`
`428
`
`Artificial jewels of glass and plastic with vapour-deposited interference layer
`systems present a great variety of very appealing colour nuances. Even
`opalescence effects can be produced by deposition of all—dielectric or dielectric-
`metallic multilayers onto rough gem surfaces [119] which are achieved by wet
`chemical etching or sand blasting of the cut glass bodies. Generally, it can be stated
`that high quality coated artificial jewels are always made from cut glass bodies.
`The finish of the facets achieved by cutting is quite superior to that obtained by
`pressing. The Swarovski Company in Wattens, Tyrol (Austria) have developed
`special machines to out
`large quantities of glass jewels and to coat
`them
`economically. Swarovski thus became the most famous and important producer of
`coated artificial jewels in the world.
`
`9.5.
`
`SEPARATION OF LIGHT BY FILTERS
`
`Light separation by filters can be performed with coloured glass or dyed gelatine
`filters. The quality of separation and the thermal stability of the filters, however,
`have been improved considerably by the use of thin film interference systems, see
`[4, 5,
`l 15].
`
`9.5.1
`
`LOW- AND HIGH-PASS EDGE FILTERS
`
`These filters are characterized by producing an abrupt change between a
`region of rejection and a region of transmission. They are generally produced from
`all-dielectric multilayer systems with corrected side bands to increase transmit-
`tance on the short or long wavelength side, as is shown in Fig. 30, or on both sides
`of the rejection region. The filters are sometimes also combined with absorbing
`
` iili
`
`
`
`
`
`
`Transmittance(%)
`
`IOU100---ji---
`
`
`
`.4- OOC) 1500 2000 2500 3000 3500 4000 4500 5000
`Wavelength (nm)
`
`Fig. 30
`
`IR Iongwave pass filter and IR shortwave pass filter.
`
`
`
`C
`C
`e
`
`,"‘."'1(("}“/3
`
`
`
`TronevniOOan:-aI0/.\
`
`F
`L
`
`
`
`TranernifianraI04-»\
`
`2'3
`
`
`
`0009
`
`

`
`429
`
`coloured glasses to improve and/or extend the rejection zone. Another way to
`extend the rejection zone is to place a second stack in series with the first and to
`ensure that their rejection regions overlap.
`In this category belong blocking or transmitting filters for separation ofbroad
`spectral ranges in the ultraviolet, the visible and the near infrared range. Such
`blockers can be used for suppression of the unwanted higher or lower orders of
`various narrow and broad band interference filters, or to block disturbing uv
`radiation and to limit the sensitivity range of a receiver. Some examples are shown
`_
`,
`in Figs. 31 and 32.
`
`100
`
`90 —
`
`80
`
`E 70
`C
`8 60 g
`
`g 50
`40 _,
`E 30
`+-
`
`C ‘
`
`20
`
`10
`
`O
`
`
`
`300
`
`400
`
`500
`Wavelength (nm)
`
`.
`600
`
`Fig. 31
`UV blocking filter / Light source spectrum: Mercury lamp.
`
`700
`
`100
`
`'53:;
`:cmc_
`,y wet
`Stated
`OdieS_
`led by
`:1oped
`them
`lcer of
`
`:latine
`
`vever,
`IS, SCC
`
`een 3'
`1 from
`15r_mt'
`lS1d€S
`
`)rbing
`
`O
`
`90
`
`BO
`
`70
`60 (I)
`A
`50 5
`
`40 .-‘‘l
`30
`
`20
`
`10
`
`.3
`8
`C
`E
`
`§
`
`C 9
`
`+-
`
`400
`
`500
`
`600
`
`900
`800
`700
`Wavelength (nm)
`
`1000 11001200
`
`Fig. 32
`MR blocking filter / Sensitivity of receivers: Silicon cell.
`
`
`
`0010
`
`

`
`greet
`greet
`prim
`cyan
`com!
`dens
`
`
`
`10C
`
`9c
`
`ac
`79
`2‘:
`6c
`‘”
`E 5c
`.33-
`4c
`5,
`5 so
`¢
`
`20
`10
`0
`
`Fig 35
`Com,
`(TL = d
`
`430
`
`Furthermore, the dichroic colour filters should be mentioned here. General—
`ly, additive filters of this type are produced in the three primary colours: blue,
`green and red. Through a combination of dielectric, mostly oxide, coatings with
`coloured glasses, colour filters achieve a complete suppression from the ultraviolet
`range to the near infrared without causing a noticeable loss oftansmittance in the
`passband region. Because the coloured glass and the cement are thermosensitive,
`the maximum thermal load is, for about 100°C, relatively small.
`lf, however,
`all-dielectric oxide systems are produced with the coatings deposited on both sides
`ofthe substrate, then the filter also has high transmittance in the pass band region
`and a broad suppression range in the visible. Cut—on and cut-off slopes are then
`relatively steep, with the result that colour outputs of high purity are achieved
`with these products. Basic designs of the red, the longwave pass, and blue, the
`shortwave pass, colour filters can be modified so that the cut-on and cut-off
`positions are shifted to other wavelengths. This change can be effected without
`altering colour filter spectral characteristics, namely its high transmission, broad
`blocking region, and steep slopes.
`Typical specifications of additive colour filters are given in Table 4.
`
`TABLE 4
`
`ADDITIVE COLOUR‘FlLTERS
`
`
`
`
`With coloured glass:
`T Z 65%
`l—j4;)O—450 nm
`
`
`T s
`
`505 - 760 nm
`
`
`
`Green
`
`T < 1%
`
`400-475 rim
`
`"
`
`T 2 75%
`
`525-550 nm
`
`
`400 - 575 nm
`
`T 2 80% J 625- 760 nm
`
`
`Subs1ratc:Coated glass laminated to coloured
`glass
`
`610-760nm
`
`Glass thickness: 2 -4 mm
`
`Thermal load:
`
`100°C maximum
`
`
`
`
`
`Blue
`
`l
`
`Green
`
`all dielectric:
`400—460 nm
`
`505 - 760 nm
`
`400 -485 nm
`
`530-555 nm
`
`590-760 nm
`
`l_l:ed
`
`
`400 - 575 nm
`
`630- 760 nm
`T 2 80%
`Substrate:Heat-resistant TEMPAX coated on
`both sides
`
`
`
`Glass thickness: I mm
`l"‘
`
`Thermal load: 400°C
`
`With such all-dielectric oxide systems, thermal loads up to about 400° C are
`readily feasible.
`Balzers subtractive colour filters are dielectric interference filters whose
`passbands extend over the spectral region of two primary colours: yellow over the
`
`0011
`
`

`
`431
`
`green and red regions, magenta over the blue and red, and cyan over blue and
`green. When subtractive colour filters are placed in the path of a light source, a
`primary colour results. Thus yellow and magenta filters yield red, yellow plus
`cyan produce green, and magenta and cyan provide blue. Through suitable
`combinations, the subtractive colour filters can produce every colour hue in any
`density to full saturation.
`Typical specifications of subtractive colour filters are given in Table 5.
`
`qeral-
`blue,
`;with
`violet
`in the
`sitive,
`vever,
`isides
`
`TABLE 5
`
`:
`i
`
`“gm”
`: then
`SUBTRACTIVE COLOUR FILTERS
`llCV€d
`e, the
`:ut-on‘
`T 2 80%
`530 — 760 nm
`’ h
`
`
`
` broad
`
`
`
`T > 75%
`
`400-460 nm
`
`
`
`
`
`
`650 — 730 nm
`
`420 — 565nm
`
`
`
`63°-Wm
`Substrate: Heat-resistant TEMPAX
`
`
`
`Glass thickness: l mm
`
`Thermal load:
`
`400°C maximum
`
`(%)
`
`Transmittance
`
`0
`
`D
`
`C are
`
`whose
`ver the
`
`400
`
`500
`
`600
`Wavelength (nm)
`
`700
`
`Fig. 33
`Colour temperature conversion filters TL/TK.
`(TL = day light, TK = artificial light)
`
`
`
`0012
`
`

`
`432
`
`
`
`
`
`
`
`Lightabsorbedoremitted,arbitraryunits.
`
`
`
`Absorption
`
`tck
`
`iflu
`the:
`
`in r
`
`ten.
`
`33:
`
`the
`
`ini
`
`fluc
`to a
`
`FIT
`rnu
`
`asc
`
`is n
`she
`
`laye
`tran
`
`star
`
`dem
`Ina»
`con
`
`9.5;
`
`tran
`
`I)ep
`narr
`
`9.5L
`
`ont
`
`nwo
`
`hafl
`vacu
`
`fihei
`
`evap
`thw
`
`Optii
`
`400
`
`450
`
`500
`
`550
`
`600
`
`Wavelength (nm)
`
`Fig. 34
`Absorption and emission of FITC-protein conjugate as function
`of wavelength.
`
`100
`
`10
`
`
`
`Transmittance(°/o)
`
`Fig. 35
`Excitation filter for FITC immuno—fluorescence.
`
`Wavelength (nm)
`
`
`
`0013
`
`

`
`
`
`433
`
`Applications for dichroic colour filters encompass TV cameras, film printers,
`telecine equipment, colour printers, colour enlargers, signal
`lighting, studio
`illumination, colour separating, and colour sorting. The stability and durability of
`these oxide coating products make them suitable for a wide range ofenvironments
`in manufacturing, the laboratory, and the photographic darkroom.
`As well as additive and subtractive colour filters, there are also colour-
`temperature conversion filters for natural and artificial light applications. Figure
`33 shows an example ofsuch filters.
`Generally, in many types of long- and shortwave-pass filters, the steepness of
`the edge is not ofcritical importance. It is important, however, with filters applied
`in fluorescence microscopy where the excitation and emission bands of special
`fluorescent tracers mayhave such a small spectral distance, that they do overlap
`to a certain degree. This happens, for example, with fluorescein-iso-thio-cyanate
`FITC, a fluorochrome used in immunofluorescence. For excitation, the maxi-
`mum absorption is at about 490 nm and the emission maximum is at 520-525 nm
`as can be seen in Fig. 34. When such an exceptional high degree of edge steepness
`is required, then the easiest way ofimproving it is to use more layers. Figure 35
`shows an example of an excitation filter consisting of more than 31 TiO2/SiO3
`layers inclusive the correcting layers in the stack. These filters show very high
`transmission of 80% minimum in the area of excitation. In the blocking area
`starting at 510 nm, the transmission in lower than 5xl0‘3. The transmission
`decreases towards longer wavelengths and is lower than lxl 0*‘ at the fluorescence
`maximum of /l: 520 nm. The red part of the spectrum is suppressed by
`combination with a special colour glass.
`
`'
`
`9.5.2 BAND PASS INTERFERENCE FILTERS
`
`Band pass filters are generally characterized by a region of possibly high
`transmission,
`limited on either side of the spectrum by regions of rejection.
`Depending on the width of the transmission region, one may distinguish between
`narrow-band and broad-band filters.
`
`9.5.2.1 NARROW-BAND FILTERS
`
`A typical narrow-band filter is the metal dielectric Fabry-Perot filter basing
`on the Fabry-Perot interferometer. An interference filter of this type consists of
`two highly reflecting but partially transmitting mirror films spaced optically one
`half wavelength apart [120-122, 4, 5]. For the production of such filters, the
`vacuum deposition method has proved most successful. In the simplest case, the
`filter is made by depositing first a silver film onto a plane glass substrate then
`evaporating a 1/ 2 or a multiple of an absorption-free dielectric material following
`this with another film of silver. For symmetry, protection and stabilization of
`optical properties of the arrangement, another plane glass is added using, for
`
`0014
`
`

`
`
`
`200
`
`300
`
`400
`
`500
`
`600
`
`700
`
`800
`
`900 1000
`
`Fig. 36
`Meta|—die|ectric interference filter FILTRAFLEX B-20 (Balzers).
`
`Wavelength (nm)
`
`example, a conventional optical cement. Figure 36 shows the spectral transmit-
`tance of a metal—dielectric F. P. Filter. The thickness of the dielectric intermediate
`
`or spacer layer determines the position of the transmission band within the
`spectrum and the degree of background transmission. The wavelength for which
`the internal multiple reflections in the forward direction are in phase will be
`strongly transmitted, other wavelengths are suppressed. First-order filters, that is,
`forward reflections differing in phase by only one wavelength, generally have a
`peak transmittance of 30 to 40% with a half width of the transmission curve of
`about 20 nm. Second-order filters, in which the forward reflections differ in phase
`by two wavelengths, may have the same peak transmittance as the first-order
`filters, but a half width of only about 10 nm. The undesired orders of the filter can
`be blocked by edge filters or coloured glasses.
`An extensive mathematical treatment was performed by Hadley and Den-
`nison [l2l, 122]. Only the most important formulae characterizing aFabry-
`Perot filter are given here
`The transmitted intensity IT is:
`
`IT = [(l+$—)2 +§r%sin2
`
`n5tscos((pS+6)}]
`
`-1
`
`The maximum transmittance Tm is:
`
`Tmax 7'' T2/(]"R)2
`
`The minimum transmission Tm.“ outside the transmittance curve is:
`
`Tmin = T/(l+R)2
`
`Finally the half width HW is given by:
`
`HW= (1-R)/X7z\/R
`
`'
`
`(12)
`
`(13)
`
`(14)
`
`(15)
`
`
`
`0015
`
`

`
`435
`
`In the equations, T = transmittance of a single mirror layer, R = reflectance of a
`single mirror layer, A=absorption of a single layer, X =order of interference,
`n,t,= optical thickness of the spacer layer and azangle of radiation within the
`layers.
`Examples of fields of application of such filters, producing monochromatic
`light, are in colourimeters, sensitometers, polarimeters, refractometers, interfero-
`meters, fluorimetrical measuring instruments, flash-photometers, microscopes,
`etc. Filters are manufactured for the near infrared and the visible range using Ag
`mirrors and for the ultraviolet using Al mirror films. The corresponding spacer
`layers are often made of cryolite, thorium fluoride, magnesium fluoride or lead
`fluoride. For infrared applications, materials such as germanium, silicon and
`tellurium and gold are also used. Most filters are designed for applications at room
`temperature and at normal
`incidence of light. Peak transmittance is shifted
`towards shorter wavelengths if either the temperature is decreased or the angle of
`incidence is increased e. g. [I23]. The angle of incidence of the light determines the
`wavelength at which transmission is maximum. In fact,
`/l,,,,,,,
`is shifted in the
`shorter wavelength direction with increasing angle of incidence and simultaneous~
`ly the transmission is slightly reduced. Inclination of the filter therefore offers the
`opportunity to move /1,,,,,, within a small range. For light beams of considerable
`convergence or divergence incident at an angle, the effect
`is to broaden the
`transmission band. Where light is polarized, the displacement varies, depending
`upon whether the polarization is parallel or normal to the plane of incidence.
`Fabry—Perot filters are also available commercially, with local continuously
`changing spectral transmittance. Such continuous filters are deposited on glass
`strips or on circular disks.
`Vital to the operation of an interference filter is a very high reflectance of the
`mirror coatings adjacent to the spacer layer. The absorption of the metal mirrors
`can be reduced and thus the maximum transmittance of the filter increased if both
`
`metal layers are increased in reflectance by additionally deposited high reflecting
`dielectric multilayers [I24]. In this way, with a first-order filter, a half width of
`2 nm and a transmittance maximum of 41 % can be obtained [I24].
`If, however,
`the metal mirrors are completely replaced by absorption-free all-dielectric high
`reflecting multilayers, one can achieve a peak transmittance of greater than 75 °/o
`with a half width of only 2 nm, which is considerably better than the usual
`metal-spacer~metal system. Figure 37 shows an example of an all dielectric
`NIR—interference filter. The relation between half width and tenth width in a
`
`Fabry—Perot filter is 1 :3. Such a transmission curve is not of ideal shape. To obtain
`a more rectangular shape of the transmittance band and to eliminate the
`disturbing influence ofabsorptions on the bandwidth, considerations analogous to
`coupling of tuned electric circuits led to acceptable results [125- I 3 I]. By coupling
`together tuned electric circuits, the resultant response curve is more rectangular
`than that of a single tuned circuit. This also happens when coupling together
`single Fabry—Perot
`filters. From the multiple half-wave filters the double
`half-wave (DHW) type of the form: // mirror / half wave spacer/ mirror / half
`wave spacer / mirror //
`is often fabricated. The filters may be either
`
`I3)
`
`14)
`
`15)
`
`
`
`0016
`
`

`
`436
`
`100
`
`90
`
`A
`‘~’\: 70
`§ 60
`g 50
`40
`C
`Q 30
`l‘
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`0
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`p
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`i: 0°
`Substrate: BK
`-
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`g
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`g
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`5
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`9
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`400 500 600 700 800 900 1000 1100 1200 1300
`
`t
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`t
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`l
`
`«
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`Q
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`9.
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`al
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`0
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`at
`
`b a
`
`1
`
`a:
`fl
`
`o.
`
`n
`If
`
`9
`
`Wavelength (nm)
`
`Fig. 37
`All—die|ectric narrowband interference filter I. = 1064 nm.
`
`metal-dielectric or all-dielectric. The relation between halfwidth and tenth width
`
`in a DHW filter is better than l:l.8.
`When using an interference filter, the uncemented mirror surface must always
`face the light source. Where filters are to be used above 40°C, the time ofexposure
`should be kept as short as possible, and in no case should temperatures of 70° C be
`exceeded. Mechanical stresses and strains can destroy a filter. It is recommended
`that filters are stored in dry air at temperatures not exceeding 40°C, e.g. [l32,
`133]. For information on the influence of neutron bombardment ofinterference
`filters, see c. g. [I34]. Each filter is guaranteed by most manufacturers for a period
`of one year. Other more special types of monochromatic filters are rather seldom
`produced and will therefore not be discussed further here. Details are given in:
`reflection interference filters [I2l, 122, 124, l35, 136];
`frustrated total reflection filters [124, 135, 137];
`induc