Applied Optics and Optical Design, Parts One and Two PDF
Preview Applied Optics and Optical Design, Parts One and Two
APPLIED OPTICS AND OPTICAL DESIGN A. E. CONRADY IN TWOPARTS PART ONE DOVER PUBLICATIONS, INC. NEW YORK PartOne copyright© 1957, 1985byDover Publications, Inc. All rights reserved. ThisDoveredition,firstpublisbedin1992,isareissueoftheeditionfirstpublishedby Doverin1957(PartI)and 1960(PartII).TheDovereditionofPartIwasanunabridged andcorrectedrepublicationoftheworkoriginallypublishedbytheOxfordUniversity Press, London,in1929.PartIIwasoriginallypublishedbyDoverPublications,Inc., in 1960; this part was a posthumous publication edited and completed by Dr. Rudolf Kingslake(then DirectorofOptical Design,EastmanKodakCompany, Rochester, New York)withtheassistanceofDr.FredH.PerrinoftheEastmanKodakCompanyResearch Laboratories. Librarv ofCongressCataloging inPublication Data Conrady, A. E. (AlexanderEugen) Applied optics and optical design I A. E. Conrady; edited and completed by RudolfKingslake. p. cm. Includes bibliographicalreferences and index. ISBN 0-486-67007-4(pbk. :v.I).- ISBN 0-486-67008-2(pbk. :v.2) 1. Optics. 2. Opticalinstruments. I. Kingslake, Rudolf. II. Title. QC371.C62 1991 535-de20 91-33198 CIP Manufacturedin the UnitedStates by CourierCorporation 67007404 www.doverpublications.com APPLIED OPTICS AND OPTICAL DESIGN A. E. CONRADY Edited and completed by RUDOLF KINGSLAKE INTWOPARTS PART TWO DOVER PUBLICATIONS, INC. NEW YORK PartTwocopyright© 1960, 1988byDoverPublications, Inc. All rights reserved. ThisDoveredition, firstpublishedin1992,isareissueoftheeditionfirstpublishedby Doverin1957(PartI)and1960(PartII).TheDovereditionofPartIwasanunabridged andcorrected republicationoftheworkoriginallypublished bytheOxfordUniversity Press,London, in1929.PartIIwasoriginallypublishedbyDoverPublications,Inc., in 1960; this part wasa posthumous publication edited and completed by Dr. Rudolf Kingslake(thenDirectorofOpticalDesign, EastmanKodakCompany,Rochester,New York)withtheassistanceofDr.FredH.PerrinoftheEastmanKodakCompanyResearch Laboratories. Library ofCongressCataloging inPuhlication Data Conrady,A. E. (AlexanderEugen) Applied optics and optical design / A. E. Conrady; edited and completed by RudolfKingslake. p. em. Includes bibliographicalreferences and index. ISBN0-486-67007-4(pbk. :v.I).- ISBN0-486-67008-2(pbk. :v.2) I. Optics. 2. Optical instruments. I. Kingslake, Rudolf. II. Title. QC37l.C62 1991 535-dc20 91-33198 CIP Manufacturedinthe UnitedStates by CourierCorporation 67008203 www.doverpublications.com INTRODUCTION ALTHOUGH even the simplestproperties oflenses are proved in this book, the proofs and their discussion are brief, being included chiefly for the purpose of establishing a uniform and consistent system of nomenclature and of sign con ventions. For that reason some acquaintance with elementary general optics will be distinctly helpful to the beginner, and the optical section of a good modern text-book on Physics will supply the desirable information. As nomen clature and sign conventions are almost sure to clash with those adopted in this book, this preliminarystudyshouldbe, asfar aspossible,limitedto the descriptive parts, keeping an open mind with regard to signs and symbols. The mathematicalknowledge which is assumed in the book does not, as a rule, go beyond ordinary geometry,algebra,and trigonometry,but analytical geometry and elements ofthe calculus are also employed in certain sections. Serious students should bear in mind that the book is arranged in strict logical order and that it should therefore be worked through systematically from beginning to end. Moreover the present volume is almost entirely devoted to the development of general methods for the solution of optical problems, with very little specialization for isolated cases of restricted interest; hence there are very few sections which could be safely omitted. Owingto thelarge amount of ground to be covered repetitions or needless elaborations have been avoided, and even facts or conclusions ofthe highest importancemay be found stated only once and in the fewest words compatiblewithclearness and completeness. There is a deplorable tendency among students to concentrate on the mathe matical equations and their proofs. These, whilst necessary and highly useful, are merelythe dry bones ofapplied optics. Thesoul ofthe subjectwill be found in the numerous pages of plain letterpress with hardly any mathematical inter mezzos, where the more important equations are discussed in order to discover their true optical significance and the best methods of applying them in the solution of practical problems. Students who intend to take up optical design asaprofessionshouldalsorealize from the very beginningthatskill and ingenuity in numerical calculations will play a prominent part in determining their value to an optical establishment; they should therefore devote a considerable part of their available time to actual numerical work and should master as soon and as completely as possible the numerous hints and suggestions on this much neglected subject which will be found in almost every chapter of the book. 2 INTRODUCTION Whilst everything included in the text will find valuable applications in solving optical problems, it is not necessary, and would indeed be quite impossible for the vast majority of people, to remember the whole contents of the book. To assist the student in singling out the principal fundamental facts which should be firmly fixed upon the memory so as to be instantly available in thinking out or discussing optical phenomena or problems when books are not at hand, brief 'special memoranda' have been added at the end of each chapter. These should prove useful when their stated purpose is borne in mind; but they should on no account be looked upon as representing everything that is of real value or importance in the particular chapter. PREFACE THIS book is the final result of about thirty-five years of continuous devotion to the study and practice of applied optics, beginning about 1893 with first attempts, purely as a scientific hobby, to fathom the mysteries of the design of telescopeandmicroscopeobjectives. Thehobbydevelopedintoaprofessionsome five years later, and a large number of new types of telescopic, microscopic, and photographic lens systems were the result, followed during the great war by the design of most of the new forms of submarine periscopes and of some other Service instruments. It was probably the uniform success of this work which causedme to be invitedto the principalteaching positionin the new Department of Technical Optics founded in 1917 at the Imperial College of Science and Technology. The increased opportunities for research thus provided, and espec iallythe close contactwithstudents,following upon along period ofwidelyvaried practical experience, have been invaluable in determining the form in which the subjectofappliedopticsispresentedin thepresentwork. Every effort has been made to limit the subjects dealt with and the methods employedtowhatthelate SilvanusP.Thomsoncalled' realOptics'andtoexclude the purely mathematical acrobatics, which he called ' examination optics'. Progress in applied optics has been retarded to a most deplorable extent by the widely accepted belief that the two principal methods of attacking individual problems, namely the elegant but approximate algebraical method and the more empirical but rigorously exact method of trigonometrical ray-tracing, must necessarily be antagonistic and mutually exclusive. It is hoped that this book will permanently establish the opposite doctrine that the two methods are ideally fitted to be applied in closest conjunction, the analytical method readily finding a rough solution (which, however, is hardly ever close enough to admit of actual execution), while the trigonometrical method quickly and systematically adds the necessaryfinishingtouches. In order to raise this co-operation of the two methods to the highest possible efficiency, the algebraical expressions have been put into such a form and the adoptedvariables have beensochosenasto rendertheprogressionfrom the rough analytical solution to the exact trigonometrical calculations as smooth and as simple as possible, the aim throughout being to reach the exact final result with the least total expenditure of time and trouble. In some cases this last demand has led to the final adoption of equations which obviously could be algebraically transformed into apparently simpler expressions, the reason being, as isexplicitly shown in one or two instances, that the algebraically simplest formula is by no means always that which can be most quickly evaluated numerically. Considerable attention is devoted throughout the book to a subject which is hardly mentioned elsewhere. As the final prescription for a new optical system can only be executed within certain limits of precision, and since, moreover, in manycases-probablythe majority-itis impossibleto correct allthe aberrations, the important question always arises in practice: At what magnitude does any iv PREFACE one aberration become a serious menace to the proper performance of a given optical system? It is this question which is answered in this book in the case of all the ordinary aberrations, chiefly on the basis of the important quarter-wave limit laid down by the third Lord Rayleigh in 1878, but strangely neglected until comparatively recent years. The present volume includes all the ordinary ray-tracing methods, the general theory of perfect optical systems, the complete theory ofthe primary aberrations, and as much ofthe higher aberrationsas is required for the design ofalltypes of telescopes,oflow-powermicroscopes,and ofthe simplestphotographicobjectives. A second volume will give the necessary additions to the theory, largely on the principle of equal optical paths, to extend the scope of the complete work to the systematicstudy and design ofpractically alltypes ofoptical systems,with special attention to high-power microscope objectives and to anastigmatic photographic objectives. A.E.C. EDITOR'S PREFACE IN attempting to reconstruct what Professor Conrady most probably intended to publish as Part II of his book Applied Optics and Optical Design, our principal source was the typewritten notes that he issued to students between 1921 and his retirement in 193I. He had expanded and partly rewritten large sections of these notes, which are reproduced here virtually unchanged; the only alterations are editorialin characterandwere made necessary by the fact thatsome sectionsofthe original Part II lecture notes had already been printed in the published edition of Part 1. These typewritten notes constitute the entire chapters on optical path differences (XII, XIII, and XVII), on optical tolerances (XIV), on the (d'- D') methodofachromatism(XV), on microscopeobjectives(XVI), and on symmetrical photographicobjectives(XIX). Mostofthe new ChapterXI wasleft by Conrady, handwritten in its final form ready for publication, bearing the heading'Chapter XI' and continuing the numerical series of section numbers and figure numbers from the end of Chapter X in Part 1. Unfortunately the manuscript ended abruptly nearthe conclusion of section [87]; butenough data were given to enable that section to be completed. The remainingsource of manuscript was Conrady's personal set of handwritten notes coveringasupplementarycourseoflectureswhichhe gave to seniorstudents during 1925 and 1926. Much of this material had already been included in ChapterVI ofthe published Part I, and there was some degree of repetition in the 1926 series, but these notes provided almost the only source of material on photo graphic objectives. After slight editing and rearranging, and with some changes in notationso as to be consistentwith the rest of the book, these notes now consti tute section [88] on photovisual objectives, sections [II5], [I16], and [I17] on simple achromatic eyepieces, section [II9] on anastigmatic landscape lenses, sections [122] and [123] on symmetrical anastigmats, and most of sections [124] and [125] on the Petzval portrait lens. Conrady's published scientific papers contain much material which he naturally incorporated into the text of this book; an exception isthe path-difference deriva tion ofthe optical sine theorem, which has been reprinted in section [96] ofPart II by kind permission of the Royal Astronomical Society. Professor Conrady wrote always for the student and for the reader who would teach himselfthe technique of optical design by his own personal effort. Feeling that such a reader would be disappointed to find only uncompleted numerical examples to illustrate the methods described in the text, I have undertaken to complete some of these examples and to add others where none existed in the original manuscript. I also took the liberty of writing full instructions for, and worked examples of, the design of a simple telephoto lens and of a Cooke triplet objective. The procedures in these instances follow strictly Conrady's notation andmethods, ofcourse, andtheyare intendedto make up obviousomissionswhich Conrady would undoubtedly have filled himself had he been able to do so. The sectionsthatIhavewritteninaccordancewiththisunderstandingare thefollowing: EDITOR'S PREFACE section [87]F, last half, on the Gauss condition; section (88], last part, on photo visual objectives; section [125], last half, on the Petzval portrait lens; the whole of section [126] on telephoto lenses; and the whole of section [127] on the Cooke triplet lens. I was also responsible for section [II3], in which the results of the OPD studies in Part II are related to the closely similar results derived by strictly geometrical methods in Chapter VI of Part I. After a long period of unchange, the methods used in the design of lenses are today suffering a drastic upheaval as a result of the introduction of, first, the electric desk calculator, and now the electronic digital computer. In Conrady's time a designer would be willing to take almost any trouble to avoid the labour of tracing numerous rays by six-figure logarithms; he would arrange his calculations sothat he couldextractthe greatest possibleamount ofinformationfrom every ray he traced, and he would use many theorems and auxiliary formulae to yield information on the properties of a lens in a region beyond that in which the rays had been traced. Conrady's own contributions to this aspect of the science are considerable: the sine theorem, the (d'- D') method of achromatism, the funda mental laws of oblique pencils, the calculation of OPD along a traced ray, the use of optical tolerances based on the Rayleigh limit, and the Seidel aberration con tribution formulae, are noteworthy instances. The analytical design methods given in the new Chapter XI indicate a number ofways by which an approximate solution can be reached quickly without tracing any rays at all, and in all his work Conrady would carry such procedures as far as he could, to the point where the need to consider finite thicknesses and apertures made ray-tracing unavoidable. Onefeelsasense ofregretthatthe moderndesignerwithhis high-speedcomputing machinery may be tempted to ignore these elegant analytical and approximate solutions in favour of blind trial-and-error ray-tracing. However, it is gratifying to observe that in some computing establishments Conrady's formulae are being rediscovered and found to be highly suitable for employment in the writing of elaborate programmes for the automatic or semi-automatic design of the simpler types of lenses. My wife has been of very great help to me in editing and completing Part II. Shealso drew the diagrams for both partsof the book, and appropriately provided the Foreword for Part II. We are both very grateful to Dr. F. H. Perrin of the Kodak Research Labora toriesfor hischaracteristicallycarefulwork in criticallyreadingthemanuscriptand making many valuable editorial suggestions. We must also express the great indebtedness of the optical world to Mr. Hay ward Cirker, president of Dover Publications Inc., for reprinting Part I and for undertaking the publication of Part II. R.K. Rochester,New York. August 1958.
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