1fg~~-PP I ied
`Optics
`
`January
`1971
`
`g
`0.-----~----~------~----~----~----~------~----~
`
`550
`
`60
`
`10
`
`530
`
`700
`
`0 r-
`0
`
`0 w
`0
`
`50
`0
`If)
`
`0
`
`y
`
`0
`=r
`0
`
`0
`
`0
`
`0
`0
`
`~+.o-o-----o~. ~-o--~~.-2o-----o~. 3-0---x-40.-4o-----o+. s-o _____ o~. s-o----o~.-7o----~o. oo
`
`CHROMATICITY DIAGRAM
`
`Vizio EX1019 Page 0001
`
`

`

`Applied
`Optics
`
`VOLUME 10
`NUMBER 1
`JANUARY
`1971
`
`Geo~e.,·;~;rot.':::.!C,:~b~"L.•t;.~~d~':r,O" Varian""• or Color Matching by 14
`A Visual Tristimulus Projection Colorimeter-A. Valberg
`Adjustment or the Munseii-Value and W*-Scales to Uniform Lightness Steps
`for Various Background Reflectancea-C. C. Semmelroth
`Internal Reflection Spectroscopy: Validity of Effective Thickness Equations
`- N. J. Herrick and A. I. Carlson
`Hadamard-Transform Exhaust-Analysis Spectrometer-J. A. Decker, Jr.
`A Grazing Incidence Monochromator for Satellite Studies of the Solar Hell
`Lyman-a Line at 303.1 A-P~ J. Bowen, J . A. Bowles, W. M. Glencross, R. J.
`Speer. A. F. Timothy, J . G. Timothy. and A . P . Willmore
`A Convenient Technique for Determ in ing the Relative Ouontum Efficiency of
`a Monochromator and Detector System-J. L. Konl, L J. Curtis, D. A.
`Chojnacki, and R. M. Schectman
`Motion Blurring with Decaying Detector Response-L Levi
`Elec~~~::-~~a:A'6fo~f the Amplitude and Phase fluctuations of a Wave
`
`8
`14
`u
`
`24
`28
`
`34
`
`38
`
`-.....42
`
`46
`51
`
`58
`
`65
`
`74
`
`11
`
`87
`
`" 105
`
`lOt
`
`~114
`11.9
`
`132
`136
`141
`
`144
`
`150
`
`154
`
`~161
`
`168
`
`174
`
`.......... 112
`
`187
`
`1!3
`
`201
`
`A Simple Double Beam Accessory for Absorption Spectroscopy-K . Leutweln
`Spectral Absorption Characteristics of the Major Components of Dust Clouds
`-D. F. Flanigan and H . P. DeLong
`Effects of Argon Atoms on the Self-Absorption and the Intensity of Hg 2537-A
`Radiation In Hg + Ar Dlschuges-T. J. H ammond and C. F. Gallo
`Statistical Band Model Parameters and Integrated Intensities for the 5.9-p,
`7.5 I'• and 11.3 " Bands of HNO, Vapor-A. Goldman. T. G. Kyle. and F. S.
`B onomo
`Radiance and Polarization of Light Reflected from Opti<J~IIy Thick Clouds(cid:173)
`G. W. Kattawar and G . N . Plass
`Rad~!~0s".;!~~~t~pt~cha,ni:~e1:ia~:!.:~~~k~edl~~~~ H~'h~~fe':~~ann~:~~~~~.e~~
`Schroeder
`Damping of Lattice Vibration s in Sollda-J . N. Plendl
`The Correction or Optical Aberrations by Neutron lrrodl1tlon-P. Sinai
`1m aves of Truncated One- Dimensional Period ic Bar T~rgets In Aberration·
`L imited Optical Systema-J. W. Foreman, Jr., G. H. Hunt, and E. K. Lawson
`Influence of Scattered Radiation on Narrow Field of VIew Communication
`links-D. E. Setzer
`Small-Angle Scattering of light by Ocean Water-H. T. Yura
`Bldi[=~~~~:~ ~~tf~~ ~~::~~t~ri!~~·R~f A~~~l~e~reen Soybean and Corn
`Cineholomicroscopy of Small Animal Mlcroclrculation-M. E. Cox, R. G.
`Buckles, and D. Whitlow
`Calorimeter for Laser Energy Measurements--M. M. Birky
`The co, Laser Signature Problem-P. C. Cia spy and Yoh-Han Pao
`co, Laser with Slmult-.neous Active and Passive 0-Swltching-0. M . Stafsud d,
`0. Ersoy. and S. P1zzica
`A Precision Variable, Double Prism Attenuator for co, Lasers-T . Oseki and
`S. Saito
`Photoluminescent Conversion of Laser Llvht for Bl1ck 1nd White and Multi·
`color Dlspl1ys. 1: Materlals-L. G. Van U ltert. D. A. Pinnow, and J. C.
`Williams
`Photoluminescent Conversion of Laser Light for Black and White and Multo·
`color Displays. Z: Systems-D. A. Pinnow. L. G. Van U otert, and M.
`Feldman
`Measurement of the Deem P•ram•ters of a L•aer Beam end Its Diffraction
`Field, Using a Hologram-T. Miyamoto and K. Yasuura
`A Contribution to the Comparison of Single Exposure •nd Multiple Exposure
`Storage Holograms-M. Lang. G. Goldmann, and P. Grar
`Holographic Subtractlon-K. Bromley. M . A. M onahan, J. F. Bryant, and B. J.
`Thompson
`A Hologr•phlc Interferometer for Me•suring Radl•tlon Energy Deposition
`Profiles In Transparent Liquids-E. K. Hu ssmllno
`·
`A Generalized Technique of Two-WavelenJth, Nondiffuse Holographic
`fnterferomet<Y"-F. Weigl
`A Technique for Recovering Doppler Line Profll•s from hbry-Perot Inter·
`ferometer Fringes of Very Low O.nslty-P. B. Hays and R. G. Roble
`Schlie reA Vlsuallz•tlon Dev ice Allowing an Arbitrary Orientation of the Lines
`with Respect to the Sc•nlling Dlrectlon-R. Grossin. M. Jannot, and S.
`Viannay
`
`January 1971 I Vol. 10, No. 1 / APPLIED OPTICS A5
`
`A monthly publication of the
`Optical Society of America
`
`J. N . Howard Editor
`P. R. Wakelfng Managing Editor
`
`Cover: See page 153.
`
`Published monthly by the Optical Socletyol
`America at 20th and Northampton Streets.
`Easton, Pa. 18042. Office of the Editor:
`FCRL, Bedford, Mass. 01730; 617·861·
`281. Office of the Managin~ Edotor:
`INC1 1613 Nineteen th Stree N.W.,
`ashonl{ton, D.C. 20009;
`202· 87·1773.
`Advertljong_ ofllce: American Institute of
`Physics, 335 E. 45th Street, New York, N.Y.
`10017; 212·MU 5·1940. Subscription rates
`gl!r year: Included in membershop dues to
`SA members; nonmembers and libraries
`$35. Songle copies $4; complete volumes
`$40Pa. Second class postage paid at Easton,
`0 Copyrll{ht 1970 by the Optical
`•
`S
`ociety of Ameroca, Inc.
`
`WW
`
`4A
`
`Vizio EX1019 Page 0002
`
`

`

`Photoluminescent Conversion of Laser Light for
`Black and White and Multicolor Displays. 1: Materials
`
`L. G. Van Uitert, D. A. Pinnow, and J. C. Williams
`
`.\ numoor. of pho~oluminet~cenL rnalerials have been found U> have properties that make them extremely
`useful ~or ~mprovm~ the quality of laser displays 118 w<•U 11.!1 offering simplification for multicolor systems.
`The pnnetplll funclton uf thfllle materials is that of eolor eonversion when coated onto a laser illuminated
`vi!'~iu~ '?!!en. A !ICO<Indary, yet signiiicMt, role is that of rendering t.he converted light incoherent.
`Th1:< elurunatcs .th.- unplfi88AIIL granular or epeddy texture 1\..""'<:iated wit.h din!(·~ viewing of diffusely acal(cid:173)
`terro co~erent light. lL L~ concluded that. virtually any vi ible color may be achieved by photoluminescent
`ronvel'!lll>fi of a mounrbromatic blue or ultraviolet la_-er beam.
`
`I.
`
`Introduction
`~n a r<'.ccnt rcvit>w of lt\Sor· di:;play technology Baker1
`pomtcd out that considcmblo motivation in this field
`~>lem!l from the promi"C of producing a cathode my tube
`typo of display with e."-'ICUI ially unlimited scr<.-cn size.
`Ho concluded that althoujl;h nde<tuate light benm modu(cid:173)
`lation and scanning technique~ arc prCJqJntly available,
`broadly applicable equipment awaits the development
`of nn efficient mull icolor ltlS(lr t-ourcc.
`Although i!uch a mult icolor source would indeed be
`d&~irable, the prospect!! for its realization, even in the
`llowever, it is clear
`distant future, arc speculative.
`that eflicicnt monochromatic or limited color mnge lm:~er
`source!'! cun and wiU be drv<'lopt'<f.l The purpo~~t• of the
`prcl!Cnt work is to show thut a monoehromntic laser
`s~urce Is !lati.sfactory for whito light and multicolor
`drsplnyt! when advantngt> is tnkcn of photoluminescence
`thO t\bHorptiun Of light o( 0110 W!LVelength and the SU~
`sequent cmiHsious at another wavelength. By prop(cid:173)
`erly coating a viewing scr(l('n with existing orp;unic and
`inorganic pho~phonl it i. possible to efficicntlv conv<'rt
`mo!lochromatic blue or ultraviolet ~r lip;ht into
`virtually any viKible colur including white. Au addi(cid:173)
`tional benefit of thi~> couver ion i1:1 the eliminution of
`the unplca.'4ant granular texture generally 1\riSocinted
`with din>et viewing of diffu ely scnttercd coherent
`light ,1 because the conv('rfed light is incoherent.
`The bo.t~ic phytJics of pbotoluminesct•nt convctl!ion is
`qwtr l!iruple. PhotonR from a light beam such ru1 a
`~r beam are ~bsorbed in fi matorial which is thereby
`ratl!(Jd to an excttcd st11tc.
`'!'his excitation equilibrates
`in a briof intervul, typicnlly JO-• sec to 10 ~flee. Equil-
`
`Thll authora are wilh Bell Telephone Laborotorif.'l!, Inc., Mur(cid:173)
`ray HiU, New Jersey 07974.
`Received 16 March 1970.
`
`150 APPLIED OPTICS I Vol. 10, No. 1 I January 1!171
`
`ibrotion can proceed both rudiutivcly by the emission of
`a photon and nonrudiativcly by, for example, a sel'ies of
`phonon interactions. A mntt'rial is considered to be a
`phosphor if radiative emis.~ion iR observed. The rela(cid:173)
`tive trt-ngth of radiative trnmitions i specified in terms
`of t be pho .. phor's quantum efficiency, defined aa the
`rotio of emitted photont~ to nbsorbed photons. In
`general, the energy of the emit ted photons is less than or
`equal to t be energy of the ltbsorbed photon ( tokes's
`Jaw). Thut is, the color of the emitted Light is either
`unchnng<'<.l or hifted in the direction of longer wave(cid:173)
`length.. In certain limited case ami- tokes (shorter
`wavelength) emis~ion is al o possible when additional
`energy is ~<upplied to the single photon e.xcited state by
`other means such as thermal excitation or multiple
`photon absorption.• In tho presrnt work we will con(cid:173)
`sider only Stokes emitting pho!'!phors which have suf(cid:173)
`ficiently high quantum efficiencies to be of interest for
`laser diRplay applications. Some emphasis will be
`placed on those materials that can be excited by the
`argon ion Jnser which is presently the most suitable
`sourer for a laser display sy tern.
`
`II. Characterization
`There are four ba..'lic propertirs that characterize
`photoluminescent materials. They nre (1) ab orption
`and emis:;iou spectra, (2) couver "ion lifetime, (3)
`quantum efficiency, and (4) ab~orption cross section.
`It should be noted that the last three propertie can be
`functions of the e."<citing \nwelength. The features
`that make a phosphor desirable for application in ltlSer
`display sy terns can be related to these properties.
`First, the phosphor must have a high absorption cross
`section for the exciting loser wavelength so that nearly
`total absorption can take place in a thin layer of mate(cid:173)
`rial that is coated ooto a screen. The phosphor should
`have an emission spectrum in a de."-irecl wavelength
`
`Vizio EX1019 Page 0003
`
`

`

`range with a high quantum efficiency, say, 50% or
`greater, since the display screen size is limited by avail(cid:173)
`the conversion
`able light intensity. In addition,
`lifetime should be sufficiently shot·t so that the screen
`will not be overly persistent; there is no perceptible
`consequence if t he lifetime is exceptionally short_$
`Finally, the phosphor should be inexpensive, stable, and
`preferably nontoxic.
`
`Ill. Materials
`Rather than attempting to cover the broad field of
`phosphors, we will discuss, b:1 way of particular ex(cid:173)
`amples, those materials that we consider to be par(cid:173)
`ticularly suitable for laser display systems. They
`generally fall into two categories, inorganic rare-earth
`phosphors and orgauic dye phosphors. To a lesser ex(cid:173)
`tent we will also consider inorganic compounds that are
`activated by transition metals and other organic mate(cid:173)
`rials such as the aromatic hydrocarbons.
`
`A. Inorganic Phosphors
`According to Pringsheim, 6 practically all molecules
`that are photoluminescent in condensed states are
`rather complex. The only exceptions are the positive
`ions of some rare-earth metals. The optical properties
`of these ions are so little perturbed by the surrounding
`medium that, even in crystals, they behave almost like
`isolated atoms, and their energy levels arc well known.7
`The rare-earth Tb!+ is a particularly useful ion since
`the wavelength for maximum absorption of its 6D4
`manifold corresponds quite closely to the blue (4880
`A) emission of the argon ion laser. When this ion is
`embedded in a properly chosen host, such as a tungstate
`or a molybdate, it will emit upon excitation a strong
`greenish-yellow color which has a peak at approximately
`5440 A.7 The lifetime is approximately 0.5 msec,
`and the quantum efficiency is high, approaching 100%.
`We have examined the performance of Na9.6Tb0.5W04
`under excitation by an argon laser ( 4 80 A) and find
`that 1-mm thick sample absorbs approximately 50%
`of the incident beam. This absorption cross section is
`substantially lower than optimum since a considerable
`thickness of material would be required to coat a display
`screen.
`
`1.0,.---------.------...,
`~
`~ ... 0.5
`
`ABSORPTION
`
`EU EMISSION
`
`2:
`tc
`..J "' 0::
`
`WAVE LENGTH (A)
`
`Fig. I. Relative absorption spectra of TbH and EuH and the
`emission spectra of Eua+. When these two rare-earth ions are
`inrluded in the same host, such as NauTbe.uEuo.uWO,, absorp(cid:173)
`lion of-argon lru;er radiation at 4_880 A is du.e to Tbl+wh.ile excita(cid:173)
`lion transfer to Eua+ results in the characteristic Eua+ emission
`spectrum which peaks in the red at 614.0 A.
`
`/EMISSION
`
`:r
`....
`~
`....
`
`0::
`
`"'0.~ ! 0::
`
`WAVE LENGTH (A)
`
`6000
`
`7000
`
`Fig. 2. Relative absorption and emission spectra of YAG:Ce.
`The broad absorption band is due toad-baud excitation.
`
`It is possible to achieve other colors by photolumines(cid:173)
`cent conversion using different rare-earth ions. For
`exam11le, Sm~+ has a peak emission at 59 0 A, EuH at
`6140 A, Dy!+ at 5740 A, and Era+ at 5520 A..7 How(cid:173)
`ever, none of these transition!-' other than those for TbH
`can be directly excited to any extent by the 4 0-A line
`of the argon laser. Generally, shorter wavelength ·
`excitation is required. However, indirect excitation of
`Eu!+ is possible through an intermediate Tb!+ ion.8
`For example, excitation transfer from TbH to EuH in
`N ao.,Tbo.2SEuo.2sW04 causes this material to emit a
`strong red color under 4 0-A illumination. The ab(cid:173)
`sorption bands of TbH and EuH and the emission of
`EuH are displayed as a function of wavelength in Fig.
`1. The absorption cro s section, quantum efficiency,
`and lifetime of this material nre s.imilar to Nao.~Tbo.~­
`W04 discussed above.
`The Ce!+ and EuH ions are exceptions to the general
`observation that the fluorescence of rare-earth ions is
`little affected by the host. This is so because their
`emissions are from d-bands which strongly interact with
`the crystal field.$ A rather unusual but useful material
`is made by adding cerium to Ya.Als01s (Y AG). The
`lower excited states of the crystal field components of
`tue 5d configumtion of the YAG: Ce composition are
`sufficiently low in energy that absorption of 4 80-A
`light hecomes appreciable. 1° Figure 2 shows the ab(cid:173)
`sorption and emission spectra in detail. Note that the
`peak of the etnission spectrum occurs at 5500 A, the
`wavlength at which the eye is most sensitive. We
`have found that at 4 0 A the absorption cross section
`is approximately 30 dB/ mm/ wt %of Ce added to the
`Y AG host. In addition to this relatively large absorp(cid:173)
`tion cross section, this compound has a very short life(cid:173)
`time of approximately 0.07 ~sec (Ref. 11) and a quan(cid:173)
`tum efficiency of approximately 70%. 10 These proper(cid:173)
`ties make YAG:Ce very attractive for display screen
`this material may be
`applications. Furthermore,
`tuned for a particular Ube. By replacing some Y with
`Gd the peaks of the absor·ption and emission spectra
`shift to somewhat longer wavelengths, while replacing
`Al with Ga causes the opposite cffect. 10 Other Ce8 + and
`Eu2+ compositions that .have been investigated9•10
`require excitation at wavelengths substantially shorter
`than 4 0 A, general!y in the ultraviolet. 4
`In addition to the rare-earth compounds, there are
`large clas8es of inorganic phosphors ~which have II- VI
`hosts such as ZnS and activators such as Bi, 1\In, Cu,
`
`January 1971 I Vol. 10, No. 1 I APPLIED OPTICS 151
`
`Vizio EX1019 Page 0004
`
`

`

`Table I. Ablorptlon and Fluorescence Bands of Dyes In
`Aqueous or Alcoholic Solutions, after Prlngsheim ~>·•
`
`Firs~
`absorption
`band
`
`l•'lnoreiltence
`Color
`Daud
`
`IIV
`
`2!)00-4600 viole~
`strong
`(32()())
`4400-.'i200
`filOO 5900 yellow-green
`(4!)40)
`(5180)
`very strong
`4500-.~ti()() li200~000 yellow
`
`(5400)
`strong
`(5170)
`4600 -5560 5180 5880 yellow
`wel\k
`5.17.>
`5165
`
`(5436)
`
`,'\500 6700 ornnge
`V('ry weak
`(6000)
`
`4 00 6000 5500 7000 rt'd
`(5500)
`strong
`(UO.iO)
`.)360 6020 yellow
`4800 5!100
`(6260)
`(55ii0)
`stnmg
`4550 0000 5600 MOO omnge
`medium
`li600 6500 orange
`medium
`
`5400 -.5900
`
`uv- 5200
`uv- fi400
`
`30()()-4_500 4000-4800 blue-violet
`nwdittm
`4750 6400 green
`5050 6700 ~reeni h-
`yellow
`{5850)
`medium
`4700 MOO green wenk
`uv-5100
`uv--5000 48ii0 6600 yellowish-
`gree_n
`strong
`
`4000 6000 5:)00-7000
`(524.0)
`(6000)
`(63!)0
`
`red ~trong
`
`yellow-red
`
`dayglow phenomenon has found considerable use in
`advertising display and is due to strong ab orp(cid:173)
`tion of blue and green Light with subsequent emission
`at the various louger wavclengths. 13
`The fluorescing hydrocarbons and dyes are em(cid:173)
`ployed in very dilute form in order to achieve optimum
`quantum efficiency. Usually pigments (solid particles
`that catTy dye) are formed by di~solving the dye in an
`organic resin solution which is subsequently condensed
`to an in~olublo atato by tho application of heat. 14 Tn
`certnin cuscR the efficiency is enhanced if the dye is
`adsorbed on rolloi<ll! such as fibers or gel particle.<> of
`high polymers. u RcprcscntMivc materials and the
`color which they fluoresce include pyrclene (blue),
`fluorescein (rellow-g!'l>cn), eosin (yellow), Rhodamine-B
`(red), Rhodaminc-60 (yellow), acridine (blue), acri(cid:173)
`flavine (yellow-green), naphtluucne red (red), Auro(cid:173)
`minc-0 (yellow-green), and 7-diethylnmino-4 methyl
`coumarin (blue) as well as other xanthene, aziue, oxa(cid:173)
`zioe, thioazine, acridine, flavin, naphthalimide, and
`coumarin derivatives. Additional d11ta on the ab ·orp(cid:173)
`tion and emission of selected dyes are given in Table I. 1
`•
`We have ext~mincd in conAidPrable detail a oaph(cid:173)
`thalimide
`dye,
`4-amino-1,8-na phthul-p-xenylimide
`(yellow-green), and two Rhodamine dyes (orange and
`red) that have been cast into an adhesive coated plastic
`film for commercial usc (Minnesota 1\fining and Manu(cid:173)
`facturing Company, Scotchcal F luorescent Film, types
`34 ' 3, 34.84, and 348.1). Their emission spectra for
`4880-A excitation, which are shown in Fig. 3, exhibit
`peaks at fi200 A (yellow-green), 0000 A (orange), and
`62001 (red). We have determined that their Lifetimes
`are all considerably less than 1 !lSCC, a nd their absorp(cid:173)
`tion cross section!! are~o large thnt the entire laser beam
`is absorbed within the thin films which are approxi(cid:173)
`mately 0.1 mm thick. Their absorption bands are
`<1uite broad, including essentially all the violet and blue
`and a portion of the green. We have estimated from
`analysis of reflection spcctr·a reported by Ward'8 that
`
`Compounds
`
`I. Xanthene
`Fhtoran
`
`Fluorescein
`(Dihydroxyfluoran)
`Eo!> itt
`(Telrabrom<JIIuo-
`rescein)
`Erythrosin
`(Tetraiodc>lluo-
`rescein)
`no~e bengale
`(Tetraiodoletra-
`rhloroBuorescein)
`llhodamine B extra
`
`1Utodamine OG
`
`Acridine red
`
`Pyronine B
`
`II. Acridine
`Acridine
`
`Acridine yellow
`Euchryaine
`
`·-...
`
`Hhoouine A
`ArriBa vine
`(Trypatla vine)
`
`rn. Azine
`Magdala red
`
`Safraoine
`IV. Thia.zine
`Thionine
`
`orauge
`4 00--6300
`medium
`(5800)
`red medium
`Met-hylene blue
`5500-7000
`• Approximate limits or band~ in A; peaks of bands in
`parentheses.
`
`and Ag, and mtuly nctivatcd tungstate.'!, molybdates,
`vanadates, phm"lphnlcs, gcrmnnatcs, a nd silicates that
`also have strong band fluorescence." We have not
`found these materials to be part iculurly useful since
`most are not readily excited by argon radiation or are
`of inadequate quantum efficiency.
`
`B. Organic Phosphors
`There arc a number of aromMic hydrocarbons and
`organic dyes !nat when proper·ly treated exhibit strong
`fluorescence over a broad portion of lhc visible spec(cid:173)
`t rum. Under white light illuminMion several of these
`appear to glow with a particular colot· ranging from
`greenish-yellow through orange to bright red. This
`
`152 APPLIED OPTICS I Vol. 10, No. 1 I January 1971
`
`0~000
`
`~000
`... VE LENGTH IAI
`
`Fig. 3. Relative emission spectra of nnphthalimide dye (3485)
`and Rhodnmine dyes (348.'3 and 3484) due to excitation by lhe
`4880-A line of an argon laser.
`
`Vizio EX1019 Page 0005
`
`

`

`their quantum efficiencies are above 50%. Thus,
`these materials are almost perfectly suited for Ia er dis(cid:173)
`play systems.
`The colors of these fluorescing dyes may be modified
`somewhat by varying the type of carrier which is used
`to form pigments and, to :1 lesser extent, by varying
`the type of vehicle, or binder, into which the pigment is
`incorporat<:d. It is also possible to modify colors by
`combining fluorescent dyes with nonfluore cent dyes
`that selectively absorb a portion of the emission spec(cid:173)
`trum. For example, the emission spect.rum of ·t he
`naphthalimide dye (ty pe 3485J show in Fig. 3 peaks at
`5300 A, in the green. Normally this fluorescence ap(cid:173)
`pears to have a yellowish-green cast due to the broad
`tail of the emission spectrum which extends into the
`yeLlow a nd red. H owever, this tail can be substan(cid:173)
`tially reduced by tho addition of a nonfluorescing green
`toner such as phthalocyatline, 13 which a bsorbs in lhe
`yellow and red. The result then is fl. t radeoff of
`brightness for tho ability to limit t he spectral content.
`In contrast to t he many yellow and rod emitting dyes,
`blue emitting dyes are less common. H owever, ex(cid:173)
`amination of pyrelene in dilute a lcoholic solutions in(cid:173)
`dicates that. it is blue fiuorescing when excited by short
`wavelength blue light such as 4579-A emission of an
`argon laser or the 441 6-A emission of a cadmium laser,
`while it becomes green fluorescing under longer wave(cid:173)
`length blue excit.at.ion such as the 48RO-A line of an a r(cid:173)
`gon laser. In addition, pigments of coumarin which
`fluoresces blue under ncar ultraviolet excitation a re
`commercially availa ble. 13
`
`IV. Conclusion
`There exists a sufficiently wide ra nge of efficient m;(cid:173)
`ganic and inorgauic phosphors t hat can be excited by
`laser wa velengths ranging from the ultraviolet to grc~r.n
`and that have emission spectra covering the entire
`visible. For example, a suitable combination of blue,
`green, and red emitting phosphors can be mude to
`fluoresce any color desired including white when illumi(cid:173)
`nated by o. blue or ultraviolet laser source.
`If the
`
`source itself is blue, a portion of its intensity may be
`directly scattered and blended with the emission from
`green and red phosphors to achieve a similar color ·
`gamut. These concepts have been verified using an .
`argon ion laser source which omitted only blue 4880-A
`radiation. In conclusion, photoluminescent conver(cid:173)
`sion of a monochroma tic laser source provides an attrac(cid:173)
`tive means for achieving white and light and multicolor
`for display system applications.
`
`The authors acknowledge with thanks helpful dis(cid:173)
`cussions with E. A. Ch andro s and C. V. Lundberg
`concerning organic dyes and pigments. The authors
`also t hank H. W. Grodkiewicz, A. G. D entai, and C . J.
`Schmidt for t he growth and preparation of test samples
`and S. H. Williamson for assistance in experimental ·
`measurements.
`References
`1. C. E. Baker, IEEE Spectrum 5, 39 (December 196S).
`2. J . E. Gcusic, II. J . Levinslein, S. Singh, R. 0. Smith, and L.
`G. Van Uitert, Appl. Phys. Lett. 12, 306 (1968).
`3. L. H . Enloe, Dell System Tech. J . 46, 1479 (1967).
`4. P . Prin~tSheim, Fluorucence and Phosphorescence (lntersci(cid:173)
`ence, New York, 1949), pp. 1- 10.
`5. J . D. Gould and W. L. Makous, I nformation Display 5,
`25 (November/ Deccmbe1· 1968).
`6. Ref. 4, pp. 285-289.
`7. L. G. Van Uitert, J. Electrochem. Soc. 114, 1048 (1967).
`8. L. G. Van Uilert and R. R. Soden, J . Chern. Phys. 36, 1289
`(1962).
`9. G. Bla.~se, W. L. Wattmaker, J . W . ter Vrugt, and A. Bril,
`Philips Res. Rep. 23, 189 (1968).
`10. G. Blas.~e and A. Bril, J . Chern. Pbys. 47, 5139 (1967).
`11. G. Blasse and A. Bril, Appl. Phys. Lett. 11 , 53 (1967).
`12. Ref. 4, pp. 594-645.
`13. Day-Gio Color Corporation, Cleveland, Ohio, Tecl1. Booklet
`No.ll70-A.
`14 . .!!:. U. Bobalek and W. von Fisher, Organic P rotective Coatings
`(Reinhold, New York, 1953), pp. ll5- 118.
`15. Ref. 4, p. 423.
`16. R. A. Ward, "The Day-Glo' Daylight Fluorescent Color
`Specification System (Day-Glo Color Corp., Cleveland,
`Ohio).
`
`COVER
`
`This mont h's cover shows constant ·hue and saturation loci derived from geodesic chroma·
`ticity diagram. The radii of the constant·saturation circlas on the ~ • ., diagram were 20n;
`the angular separations of points were 18°/n. The constant·hue loci shown correspond to
`radii separated by t s • in t he f ,'! diagram.
`
`January 1971 I Vol. 10, No. 1 I APPLIED OPTICS 153
`
`Vizio EX1019 Page 0006
`
`