AFFIDAVIT OF Pamela Stansbury
`
`STATE OF NEW YORK
`
`COUNTY OF TOMPKINS
`
`)
`) ss.
`)
`
`Pamela Stansbury being offull age and duly sworn, deposes and says as follows:
`
`1. I am an employee of the Cornell University Library, and specifically Library Technical
`Services, located at Cornell University, Ithaca, New York 14853. I have personal
`knowledge of the facts set forth below.
`
`2. I am the Administrative Supervisor in Library Technical Services, which maintains
`bibliographical and processing information for many historical documents. I have held
`such position since 1996.
`
`3. Included in the Library's historical collection are various publications. As part of that
`collection, the Library maintains custody of an original issue of Applied optics, Volume
`10, Number 1, January 1971, which includes the paper Photoluminescent conversion
`of laser light for black and white and multicolor displays. 2: Systems I by D.A.
`Pinnow, L.G. Van Uitert, and M. Feldman.
`
`4. Mr. Richard F. Moncrief requested information about Applied optics, Volume 10,
`Number 1, January 1971 - specifically when this item was first made publicly available
`by the Library. As best I can determine, the publication was publicly available at the
`Cornell University Library as January 5, 1971.
`
`ANDREA DENISE SMITH COLON
`~
`!NOTARY PUBUC-STATE OF NEW YORK
`Tompkins County
`Registration #01SM6276256
`Commission Exp. 02/11/20l1
`
`Vizio EX1022 Page 0001
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`VIZIO 1017
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`

`
`plied
`Optics
`
`January
`1971
`
`0
`OJ
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`CHROMATICITY DIAGRAM
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`Vizio EX1022 Page 0002
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`VIZIO 1017
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`
`Applied
`Optics
`
`VOLUME 10
`NUMBER 1
`JANUARY
`1971
`
`• 14
`
`2A
`21
`
`38
`
`-.....42
`
`46
`51
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`5I
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`65
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`74
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`11
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`17
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`" 105
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`101
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`"""U4
`lU
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`1.21
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`U2
`136
`141
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`144
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`150
`
`154
`
`~151
`
`lil
`
`174
`
`........ liZ
`
`117
`
`lU
`
`201
`
`Geod'esic Chromaticity Diagram BaHCI on Variances of Color Matching by 14
`Normal Obser"er-o. L MacAdam
`A Visual Trlatlmulus Projection Colorimeter-A . Valberg
`Adjustment of the Mun .. II-Volue and W ._Scales to Uniform Lightness Steps
`for Various Background Reflectance-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. Dec ker, Jr.
`A Grazlnl Incidence Monochromator for Satellite Studies of the Solar Hell
`Lyman .... Line at JOl.l A-P: J. Bowen, J . A. Bowles. W. M . Glencross, R. J.
`Speer, A. F. Timothy, J . G. Timothy. and A. P. WUimore
`A Convenient Technique for Determining the Rolatlve Quantum EHicloncy of
`a Monochromator a_nd Detector System-J. L. Konl, L. J . Curtl5, 0 . A.
`ChoJnacki, and R. M. Schectman
`Motion Blurring with Decaying Detector Response--L. Levi
`Et·~~::..!'rru:Ar;,foftr the Amplitude and Pha5e fluctuations of a Wavo
`
`A Simple Ooubl_e Beam Accessory for Absorption Spectroscopy-K. Leutweln
`Spec'lral Absorption Characterlstlu of the Major Components of Dust Clouds
`- 0. F. Flanlgan and H . P. CeLona
`Effec'la of Argon Atoms on the S.lf-AbiiOrption and the lnten_slty of He ZSJ7-I.
`Radiation In He + Ar Dlscharee-T. J . Hammond and C. 1". Gallo
`Stat~~~~~~::1~.lM,.'1~'n::r:t":t~-o: vaar;:,:~t;._~~~;e.:tm1:~~~~~~~~fe'. ~hn°d 5r~s:
`B onomo
`Radiance and Polarization of Light Reflected from Optically Thick Clouds(cid:173)
`G. W. Kettawar and G. N. Plass
`Radlatlon-lnduced Chan••• In Rofractlwe Index and Absorption Coefflclent
`for Several OpUcal Material-D. R. Olson , H. 0. Dieselman, and J. 8 .
`Schroeder
`Damping ot Lattll;e Vlbratloas In Solld-J. N . Plendl
`The Correc11on of Optlc,al Aberrations by Neutron lrradl•tlon-P. Sinal
`Images of Truncated One-Dimensional Periodic Bar Tar .. ts In Aberration·
`Limited Optical System~. W. Foreman, Jr .. G. H. Hunt , end E. K . Lawson
`Influence of Scattered Radiation on Narrow Field of VIew Communication
`Unk-0 . E. Setzer
`Small-Angle Scatt_erlng of U.ht by Ocean Water-H. T . Yura
`Bldll:'.~;~~ ~~H'!~ ~~:;:t~f'!~~~·R~fA~~~~::r~raen Soybean •nd Corn
`ClneholomkroKOpy of Small Animal Mlcroclrculation-M . E. Cox, R. G.
`IBuckles, and D. Whi tlow
`Calorimeter for La .. r Enerty Measurement-M. M. Birky
`Tho co, Laser Signature Problom-P. C. Claspy and Yoh·Han Pao
`CO, Laserwlth Slmultan-us Activo and Passive O ·Swltc:hlng--0. M . Stafsudd,
`0 . Ersoy, and S. Pinlca
`A Precision Variable, Double Prism Attenuator for COt Laser-T. Osekl and
`S. Saito
`Photoluminescent Con"erslon of La .. r Light for Black and White end Multi·
`color Displays. 1: Materlai-L. G. Van U i tert, 0. A. Pinno w , and J. C.
`Williams
`Photoluminescent Con"erslon of La .. r Light for Black and White and Multi·
`color Displays. Z: System-D. A. Pinnow, L. G. Van U lt ert, and M.
`Feldman
`Measurement of the Beam Parameters of a Laser Beam and Its Diffraction
`Field, Using a Hologra-T . Miyamoto a nd K. Yasuura
`A Contribution to the Comparison of Single Exposure and Multiple Exposure
`Stora1• Hologram-M. Lang, G. Goldmann, and P. Graf
`Holoeraphk Subtrac'llon-K. Bromley. M _ A. M onahan, J. F. Bryant. and B. J.
`Thompson
`A Holelraphk Interferometer for Measuring Radiation Ene rgy Deposition
`PrOfiles In Transparent Liquid-E. K . Hussmann
`A Gener•llzed Tedlnlque of Two-Wavelen]th, NondiHv.. Hologra11hk
`Interferometry-F. Wel&l
`A Techalque for Recoverl"' Oopplor Line Proflln from Fabry-Perot l"ter·
`feromnter Fringes of Very Low Oensity-P. B. Hays and R. G. Roble
`Schlleroa VIsualization Device Allowing an Arbitrary Orientation of the Unes
`wltll ltespect to the Scan"'"' Dlrect~R . Grossln , M. J annot , and S.
`Vlannay
`
`J anuary 1971 / Vol. 10, No. 1 / APPLIED OPTICS A5
`
`A monthly publication of the
`Optical Society of America
`
`J. H. Howard Editor
`P.R. Wakellng Managing Editor
`
`Cower: See page 151.
`
`Published monthly by the Optical Society ol
`AmeriQ at 20th end 'Northampton Streets,
`Easton, Pa. 11042. Office of the Editor:
`AFCRL. Bedford, Mass. 01730: 617-161·
`42111. Office of the Managing Editor:
`WINC1 1613 Ntneteenth ~eel• N .W ..
`WashmKton, D.C. 20009:
`202...,87-lm.
`Advartising offlce: American Institute of
`P_h~slca~ 335 E. 45th Street, New York, N .Y.
`111117: <12·MU 5-1940. Subsetlpbon rates
`~year: included tn membership dues to
`OSA m'mbera; nonmembers and libraries
`• Second class postage paid at Easton1
`. . 0 CopyTi~t 1970 by the Optiea
`Soc
`tety of Amertea, Inc.
`
`1!. Stn&le copies $4; complete volumes
`
`Vizio EX1022 Page 0003
`
`VIZIO 1017
`
`

`
`Photolu_minescent ~onversion of Laser Light for Black
`and Wh1te and Mult1color Displays. 2: Systems
`
`D. A. Pinnow, L. G. Van Uitert, and M. Feldman
`
`Heoont .technulogietu development.' permit the m'>dtdation and scanning or laser beams at rateR c'Ompa(cid:173)
`rablo ~tt.h ~ho~e or ~lcctron beams in television receivera. This accounts for much of the current interest in
`lAser t~lummatoo d~:~play ~yatem• wbkh are not constrained in si~e, as jg the cathode ray tube, by the
`ne~'!Stty of II vacuum cnclo3ure. The purpose of thll pre ent work is to show bow photolumine.~ceut ma(cid:173)
`ten~ls ca? be ~~~ in Cl.lnjunction with recently developed aroustooptic deBectol'l.l and modulatol'l.l to
`achteve lugb Qualtty. Ja,er di.iphly system'!. The principal function of the photoluminescent materials il!
`~hat of ~lor \lill\Ve~~·on. when ~oalcd onto a viewing screen. This allows an additional degree of freedom
`Ul lase•· d~p!ay ongm~ong by removing lhe spectral constrain Ill imposed by the limited number of practical
`lJII!Cr emtsstons. Varto~.,; scbelll&l for both black and white and mwLicolor displays are explored.
`So~e of the COI~cepts. wlurh evolvt.>d have been experimentally verified by the operation of a system which
`proJected the v1deo stgn&l from a PICTUHEPI[ONE set. Tbe ~ource was an argon ionla~er which emit(cid:173)
`ted a ~onochromatic blue (4 0-A) beam. Afler acoustooptic modtdation and deBertion, the blue beam
`w.M dtre<'l-ed to a pho•phor screen where it wa.~ converted into a brighter and speckle-free black and white
`dtNp)ay.
`
`I.
`
`Introduction
`Iu PtLrt 11 we discussed the characteristics of a
`'-... number of photoluminescent materials that can effi(cid:173)
`ciently convert ultraviolet and visible light into light of
`a similnr or longet· wavelength spectral content. Here
`we will confliuer the application of these materials to
`white light and rnulticolor displays that use laser
`BOUJ'Ccs. A considerable effort in the field of laser
`scanned clisplo.ys hn been prompted by potential
`applicntions for which the cathode ray tube (CRT) is
`unsuited. One purticulnrly important application of
`laser systems i that of lt\rge screen multicolor displny.
`Such syst,oms hn.ve becu successfulJy developed in a
`number of labomtories1 including Zenith, Texus Instru(cid:173)
`ments, General Telephone and Electronics, and Hitachi.
`In general, they :u·e COillplicatecl, expensive and re-(cid:173)
`qui~~d 1\. ubstantiul and careful engineering ~fJort. A
`maJOr source of engineering complication has been the
`necessity of using three separately modulated laser
`beams of different colors to achieve the desired color
`gamut and the use in many cases of mechanical scanning
`motion. We have found that a greater freedom of
`ac~ion as well a~ possible simplifications could re ult by
`usmg photolunu ncflccnt scrocns to provide some
`switching action between colors. In this paper we will
`describe some t>chemes for color switching and the
`
`The authors are with BeU Telephone Laboratories, Inc., Mur(cid:173)
`ray fJill, New Jersey 07974.
`Received 16 March 1970.
`
`154 APPLIED OPTICS I Vol. 10, No. 1 I January 1971
`
`systems they make possible. We will al.o r<'port
`experimental results of a particularly simple la rge
`screen black and white system which is speckle-free
`and provides PICTUREPHONE resolution.
`In discussing laser display systems it is instructive to
`compnre them with the conventional CRT systems.
`technological advances
`in acou tooptics'·4
`Hocent
`and electrooptics• permit efficient and inertialess modu(cid:173)
`lation and scanning of laser b eams at rates approaching
`or compt\rable with tho e of electron beams in tclevi. ion
`CRT's. The principal diffe1·ence bct.weeu laser and
`CRT systems is not in resolution but in screen shape
`and size. Laser systems are inherently projection
`systems which can use flat screens; while the conven(cid:173)
`tional CRT, which is most often directly viewed, has
`considerable volume. Generally, the size of a CRT
`screen is limited br mechanical considerations to at
`most 76 em in diameter.6 Even if the CRT ima"e i
`projected, the viewing area. is constrained by the light
`intensity that can be developed a t the CRT screen.
`l n
`order to provide a black and white picture with bright(cid:173)
`nes comparable with tho.t of a typic..'ll motion picture
`display the projection CRT screen size is limited to
`approximately 2 m! even with anode voltages on tl10
`order o[ 75,000 V, wllere x-ray radiation and hc1.1.t
`dissipation become serious problems.8
`In contrast,
`screen heat dissipation is not a problem in laser di.::;play,
`since the beam is directly projected to as large an area
`as can be comfortably viewed with the available laser
`intensity. A rough estimate of the relation between
`light intensity and viewing area is tha t 1 W to 2 W of
`
`Vizio EX1022 Page 0004
`
`VIZIO 1017
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`

`
`available laser light are required for each square meter
`of a diffusing screen to achieve typical television bright(cid:173)
`ness levels,' while a factor of 3 less in intensity is satis(cid:173)
`factory for theater viewing. For certain applications,
`directional screens can be used which reduce the re(cid:173)
`quired laser power by factors of up to several hundred.
`The laser source is a limiting factor in many display
`system designs. By taking advantage of photolumines(cid:173)
`cent color conversion we can remove spectral con(cid:173)
`straints imposed by the limited number of practical
`laser emission wavelengths. Of the presently known
`laser types, the argon ion la er has already proven
`satisfactory for long term stable operation at a level of
`several watts,8 and experimental units have demon(cid:173)
`strated output. up to 100 W.9 Although this laser is
`satisfactory for a display system source in almost all
`respects, its efficiency is typically only on the order of
`several hundredths of 1 o/o.10 Thus an argon laser
`source adequate to illuminate a 1 m2 screen would re(cid:173)
`In com(cid:173)
`quire several killowatts of electrical power.
`parison, only a few watts of electrical power are needed
`for modulation and scanning of the laser beam. a Be(cid:173)
`cause of this laser inefficiency the operating expense fo;:
`a display system using an argon laser source will tend
`to limit its applications either to commercial uses
`involving large audiences or uses where very low light
`intensities are acceptable. However, it should be
`pointed out that low efficiency is certainly not funda(cid:173)
`mental to laser operation. For example, operation of
`an infrared (10600 A) Nd:YAG laser at 2.4% effi(cid:173)
`ciency has already been demonstrated, 11 and efficiencies
`of approximately 10% appear to be po ible. 12
`For the present, however, the argon ion Ia er is the
`most suitttble prototype for a display system source.
`It has prominent emission lines in the blue (4 0 A)
`and green (5145 A). Because photoluminescent con- .
`version can only produce light of a similar or longer
`wavelength, it is essential that the source have at least
`one blue or ultraviolet emis ion. The additional
`emission of a second color, such ns the green line of the
`argon laser, can be used to advantage in certain systems
`that will be di cussed in , ec. III. By using phosphors
`described in Part 1, 1 it is po::;sible to convert a portion of
`the blue-green beam into red, which is the remaining
`componeut necessary for a multicolor display. This
`technique is substantially simpler than the alternate
`approach taken by others2 of adding an additionnl red
`Ia er source to the di play system and avoids the
`problem that presently available red lasers are even
`less suitable for a display system than the argon laser.
`The two principal choices are the He-Ne laser (632 A),
`which is inherently limited to low power operation for
`reasonable sizes by the low $ain per unit length, 13 and
`the krypton ion laser (6471 A), which is nearly an order
`of magnitude less efficient than the argon laser. 14 An
`additional advantage of photoluminescence is that the
`converted light is incoherent so that tho unpleasant
`granular or speckled texture generally associated with
`viewing diffusely scattered coherent light is elimi(cid:173)
`nated.u
`The recently developed Cd- Hc laser which emits in
`
`the blue (44i6 A) should also servll as a useful prototype
`ource, although its intensity is limited like that of the
`He-Ne laser. 10 In addit.ion to the above lasers, it is
`possible to make multicolor laser hybrids by combining
`two or more gases into a single laser tube.17 Experi(cid:173)
`ments with mixed gas lasers which combine argon and
`krypton or· He- re-ed to achieve mult.icolor emission
`indicate that the over-a It efficiency of the mixed systems
`arc considerably less than optimized lasers having
`single components. For e..xample, the red emi ion
`from a He- Je-Cd laser has beeu observed to be only
`about one-fourth of that from an optimjzed He-I\e
`Jaser. 17 Thus, the present hybrids have a serious
`problem because of their inefficiency.
`
`II. Color Control
`There are many analogies between display systems
`that use electron beam sources and those that use laser
`beams. For example, both types of beam can be used
`to illuminate a phosphor which in turn produces a
`visible color. In the standard color CRT display three
`spatially separated electron guns are used to illuminate,
`respectively, three different colored phosphors through
`a shadow mask. A similar technique is also practical
`with laser displays. Thus, one method for achieving
`multicolor is by illuminating from different spatial
`directions.
`An alternate method for achieving a multicolor effect
`with a CRT is the use oi a single electron gun which
`excites a white phosphor screen located behind a ro(cid:173)
`tating multicolor wheel. 18 Transparent red, blue, and
`green segments of the wheel sequentially appear in
`front of Lhe CR1' resulting in a repeating sequence of
`di crete color frames. The wheel rotate sufficiently
`fast so that an observer cannot distinguish the separate
`color frames but instead sees 011ly the total effect.
`V ariationJS on this approach can all be categorized as
`active (i.e., moving) screen methods.
`imilar methods
`arc also possible with a laser. system, although the
`scr.een may be substantially different from that used in
`the CRT system.
`In addHion to these well-known methods, which are
`applicable to both electron beam and laser beam illu(cid:173)
`mination, there are several unique features of laser
`beams which can be used to advantage in achieving a
`multicolor system. First, the laser beam itself may
`provide at least one color, and in the important case of
`·ext,
`the argon ion la.rer there are two distinct colors.
`a laser beam, or for that matter any light beam, has
`two orthogonal polarization states which can be used
`to transmit separate color information. And, finally,
`light beams can be brought to a focus in very short
`distances by passive elements such as plastlc lenslets
`which can be made an integral part of a viewing screen.
`The internationally accepted OlE chromaticity dia(cid:173)
`gram 1~ shown in Fig. 1 c:m be used as a guide in assessing
`the color quality of a display system.
`In this diagram
`the saturated (monochromatic) colors are located on the
`perimeter of the horseshoe shaped plot, while colors of
`decreasing saturation approach illuminant C which is
`
`January 1971 I Vol. 10, No.1 I APPLIED OPTICS 155
`
`Vizio EX1022 Page 0005
`
`VIZIO 1017
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`

`
`converted light from either Rhodamiue dye phosphors,
`type 3483 or 34 4, can produce a white appea•·ance
`since a straight line connecting these primaries on the
`chromaticity diagram passes very near illuminant C.
`0-A light and converted
`Similarly the combination of
`light f1·om a YAG :Ce phosphor will produce a somewhat
`yellowish-white appearance since the line connecting
`these primaries passes above illuminant C. To achieve
`a truer white with this phosphor requires a tihorter la ·er
`wavelength such as the less intense 4579-A line of the
`argon laser or the 4416-A line of the Cd- He laser.
`A combination of more than two primarie can a! o
`be u ed to produce white. As an e:«ample, a Cd- He
`laser beam which illuminates a correctly proportioned
`mi~ture of ~fgO and dye phosphors 3483 and 34 5 can
`be used to aebieve a white appearnncc. Alternately,
`the MgO could be replaced by pyrelene (a blue to blue
`converting phosphor) to eliminate speckle completely.
`R egardless of how many pho-·phors are used, it is
`apparent from tl10 chromaticity diagram that a nec(cid:173)
`essary condition for achieving a true white is thnt the
`illumino.ting laser beam have a wavelength of approxi(cid:173)
`mately 4900 A or shorter. Otherwise it would be
`impo~ ible to include illuminant 0 within a. polygon
`who~e primm·ie are the source and any combination of
`longer wavelengths t,ho.t can be achieved by conver::sion.
`FortunMely, the argon ion l11Ser can satisfy this nec(cid:173)
`essar\' condition.
`A fnctor which must be considered in the choice of
`photoluminescent materials is the relative sensitivity of
`the eye. 20 Figure 2 clearly demonstrates that there is
`an incren ingly steep falloff in the eye's sensitivity as
`wavelength varies from the yellow-green portion of
`the spectrum at about 5550 A. Thus, for a fixed laser
`power and a fixed phosphor conver::~ioo efficiency, the
`bright ness of the screen depends critically u pon the
`emi sion spectrum of the phosphor.
`!11 particular, the
`bright c. t ·creen will favor the yellow-green emitting
`
`'~oco
`
`eoco
`6000
`WIVE LENGTH (AI
`
`1000
`
`Fig. 2. T he relalive sensitivity or ~standard normal eye to light
`or varying wavelength.
`
`Fig. J. The OlE chromAticity diagram. The dotted lines en(cid:173)
`close lhe color gamut of a shadow mn.•k <·ulor ralhooe ray tube.
`
`a white color equivalent to twerugc daylight illumi(cid:173)
`nation. Every real color, rcgardlc!:!S of its spectral
`complexity, can be repro ·cnted by ~~single p<1int on or
`within this plot. A straight line conn(>ctiug nny two
`points (primaries) represents the locus of possible
`colors tbttl cnn be ach ieved by blending the primaries
`in1ilurly, the gnmut of colors
`in varying proportions.
`pollsible by tho combination of more than two primaries
`aro t hose that fall wit hill the polygon dot ermined by
`straight lines which co1uH~ct a.djaccn1 primaries. As an
`example, the dotted triatlgle in Fig. 1 encloses the color
`gamut of a. hadow mask color CRT. For compnrison
`wo have also shown the major <:admium and argon laser
`' 'lines at 4416 A, 4 0 A, and 5145 A, as woll as tho
`emissions of the YAG:Ce pho phor and the three
`organic dye phosphors (type 34 3, 34 41 and 348.1)
`which are discussed iu Sec. liT of Part 1. 1 The arrow
`on the type 3485 dye emission shows the efT oct of adding
`phthalocyanine, which is also discussed in Pnrt 1. It
`can be seen that the combina.tion of blue light (4416 A
`or 4880 A) from either of these laser sources a nd emis(cid:173)
`sion from the 34 3 and 34 5 phosphors results in a
`color gamut similar tot hat of the CR'l'.
`
`Ill. Exploratory Systems
`Various laser displf1y systems are proposed and
`evaluated in this section. They nre presented in such
`1111 order that tho relative advantages and disadvantages
`become apparent. The first and simplest system con(cid:173)
`corns the conversion of a monochromatic display into
`black and white. The remaining systems are for
`multicolor displays.
`A. Black and White
`A black and white display can be achieved by scan(cid:173)
`ning a monochromatic laser beam on a viewing screen
`that is coated with an appropriate blend of phosphors
`and direct scattering materials such as powdered MgO.
`For example, a. combination of scattered light from a
`blue argon ion laser beam (4880 A) and blue to red
`
`156 APPLIED OPTICS / Vol. 10, No. 1 I January 1971
`
`Vizio EX1022 Page 0006
`
`VIZIO 1017
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`

`
`.....
`
`Fig. 3. Sehemal it of lbe rxpcriment~l loser J>mjccliun system.
`
`pho ·phors, while the requirement for 1t true white will
`result in a tradeoff in brightnc ·. Clcnrly, a rompl'O(cid:173)
`mise is necessary in a Laser display who1'1c ~crccn size is
`limited by brightnc:.;s.
`In order to test some of the above coucoptll, a display
`screen was fabricated by dusting YAG :Cc powder over
`a white cardboard sheet that had been coated with a
`transparent glue. This screen was used in conjunction
`with a real time test disf21ay system which used an argon
`0 A) and solid state, ucoustooptic
`ion laser source (
`deflectors. 3 These acoulltooptic devices deflect the
`light beam by an angle directly propo•·tional to the
`rrequoncy of tho applied electrical , ignnl, while the
`intensity of the deflected beam is approximately propor(cid:173)
`tional tot he drive power. :J,n The video signal for this
`system was supplied by a l\lod I PICTUREPHONE
`unit, which al ·o served as a monitor when operated in
`the self-view mode. The system schema! ic il:l ·hown in
`Fig. 3. It should be noted that the lllrge bandwidth
`(75 MHz) of these recently developed acoustooptic
`deflectors allowed unu ual simplicity in tlu~t the same
`device was used for both horizontal deflection a nd fot·
`video modulation. The deflectors were driven by
`varactor oscilln.torll which had swept. frequency outputs
`that were synchronized with the horizontal and vertical
`deflections in the PICTUREPHONE set. At the
`same time tho video signal was u eel to amplitude
`modulate the horizontal frequency drive and hence the
`deflected Light. Tho resulting imago r·esolut ion on the
`YAG:Ce phosphor screen was nearly as good ns that on
`tho CRT monitor. A direct comparison ran be seen in
`L•'ig. 4. The pho>;phor screen dispersed I ho light. in a
`lambcrtian manner with a quantum efficiency of ttpprox(cid:173)
`imately 70%. Visually the picture appc~trcd llpeckle(cid:173)
`free and conRiderably brighter than :t whit<' sheet of
`paper illuminated by the same blue lip;ht. The ·omc(cid:173)
`what yellowish appearance of the screen could be cor(cid:173)
`rected by tuning the laser to lhe weaker 4.379-. emission
`line.
`Certnin details of thi system willuow be dUicu 'Sed
`$ince they are generally relevant to the dCllign of oper(cid:173)
`ating systems. The laser beam entering the adjacent
`deflectors was collimnlcd with a simple t clc.«cope and
`shaped with a prism to an elliptical crosR section having
`principal ~~..xes of3.5 mm and 7.0 mm. Thil:l cor-responds
`to filling_ times of approximately I !-'sec and 2 !-!Sec,
`
`respectively, in the l10rizontul and vertical deflectors
`since the sound velocity in the crystalline lead molyb(cid:173)
`date ncoust ooptic medium is approximately 3.5 mm
`!-!Scc- 1
`• The theoretical resolution of a deflector in
`terms of standard TV lines is simply the product of the
`bandwidth a nd the filling time. 2·u Thus, the 75-MHz
`bandwidth of the deflectors allowed a theoretical reso(cid:173)
`lution of 75 lines horizontally and 150 lines vertically.
`At the time oft he experiment this resolution wa: deter(cid:173)
`miued by the size of the available lead molybdate
`crystals which set an upper limit on the filling times.
`Larger crystals arc now available which would allow
`525-linc resolution. The l\ lod I PICTUREPHO 1E
`set has n, rcsolut ion of about 50 horizontal lines by 275
`vertical lines. Thus the frequency response of the
`PICTUREPHO~E set limited tbe borizontul resolu(cid:173)
`tion of the laser display to 50 lines while the vertical
`resolution was consi~c~tent with that theoretically cal(cid:173)
`culated. Once aligned, the ystem wa:! tnble and the
`
`(A)
`
`MOO I PICTUREPHONE CRT DISPLAY
`
`(B)
`
`1100 I PIC'I'UREJittOiE LAIER DIM.AY
`
`Fig. 4. A ~fod I PlCTUREPUO~E display (A) as soon on a
`CRT monitor and (B) a:~ projected onto a YAG:Ce screen WJing
`tb~ laser syaslcm described in the text.
`
`January 1971 I Vol. 10, No.1 I APPLIED OPTICS 157
`
`Vizio EX1022 Page 0007
`
`VIZIO 1017
`
`

`
`B• BLUE
`G• GREEN
`R• REO
`
`(a) A rotating color wheel screen which is coated with red
`Fig. 5.
`(R), blue (B), and green (G) phosphors.
`(b) Rotating prisms
`which perform the same function as the color wheel but occupy
`less space.
`
`picture remained in focus for hours without readjust-(cid:173)
`ment.
`Screen brightness, in addition to resolution, is an
`important measure of the performance of a projection
`system. In our experimental system the laser source
`intensity was 0.5 W; however, only 20 m W of light
`reached the screen (open aperture), representing a.
`..,
`' 14-dB optical loss. Of this, 10 dB of Joss can be attrib(cid:173)
`uted to reflections from uncoated optical surfaces
`which could for the most part be recovered by applying
`antireflection coatings. Another 3 dB were lost in the
`vertical deflector which could not be operated at a
`higher electrical power level (0.5 W) without causing
`noticeable optical distortion due to ohmic heating of
`the transducer electrodes. This heating problem has
`been corrected in subsequent deflectors; however, one
`should still anticipate a 1-dB to 2-dB optical loss in a
`well designed deflector due to a practical limitation
`which forces a tradeoff between deflection efficiency and
`bandwidth. The remaining 1-dB loss in the experi(cid:173)
`mental system was due to the horizontal deflector which
`could operate at a higher peak power than the vertical
`deflector because the video signal modulated the drive
`level such that the average power remained less than
`0.5 W. The picture contrast ratio was limited only by
`the extent to which the drive to the horizontal deflector
`could be amplitude modulated.
`
`B. Multicolor
`In the spirit of the rotnting color wheel in front of a
`CRT which is used to produce a repeating sequence of
`discrete red, blue, and green color frames, one can make
`a similar screen for a laser display which is coated with
`red, blue, and green fluorescing materials. It is ap-
`
`158 APPLIED OPTICS I Vol. 10, No. 1 I January 1971
`
`parent from Fig. 5(a) that such a wheel would have a
`diameter more than twice the height of the screen. The
`wheel size would become excessive for most large screen
`applications. An interesting alternative to overcome
`this difficulty is the use of a series of parallel rotating
`prisms as shown in Fig. 5(b). Each facet of the prism
`can be coated with either a phosphor or a light scattering
`material. In this case the rotating elements require an
`area no greater than that of the viewing screen itself.
`In order to avoid flicker, the framing rate must be at
`least 40 per sec 18• 23 corresponding to a prism rotation
`speed of 2400 rpm (three color fields per frame).
`The advantage of this system is that it uses the
`simplest possible projection system consisting of a
`laser and beam modulator-deflector of no greater com(cid:173)
`plexity than the one which was already demonstrated
`to be satisfactory for the black and white display. The
`disadvantage is that the burden of performance rests
`upon the screen whose moderately high speed mechan(cid:173)
`ical components would generate some associated noise
`and would require maintenance. It is felt that this
`disadvantage is sufficiently serious to preclude use of
`active screen systems for general applications. Atten(cid:173)
`tion will therefore be turned to passive screens.
`In any system which uses a passive viewing screen,
`the multicolor information must be projected through
`three distinct routes, which we will call color channels.
`A color channel can take on several different forms such
`as spatially or angularly separated beams of the same
`color, orthogonal polarization states of a single beam,
`or different laser wavelengths which have collinear
`propagation.
`The simplest example of a passive yet multicolor
`viewing screen is one that is repetitively striped with
`one or more different phosphors. The stripe period
`must be small enough so that an observer cannot detect
`the separate lines, yet the deflection system must have
`sufficient resolution so that each set of lines coated with
`a similar phosphor (i.e., each spatially resolved color
`channel) can be individually illuminated. Tho advan(cid:173)
`tage of this system is its relative simplicity, requiring
`only a single laser source and scanner as well as a passive
`viewing screen. However, there are two serious
`problems which render the system impractical. First,
`the projection system must be critically aligned with
`respect to the screen to ensure satisfactory color regis(cid:173)
`tration; and second, a factor of 2 (in the case of a
`bichromatic laser) or 3 (in the case of a monochromatic
`laser) in vertical resolution of the projection system is
`sacrificed in ordet· to establish the necessary color
`channels. Fortunately, these disadvantages can be
`overcome with minor modifications.
`The problems of critical alignment and loss of vertical
`resolution discussed above can be eliminated by the
`use of a shadow mask similar to those in present color
`cathode ray tubes. 18 Consider, for example, a system
`in which a monochromatic laser beam is first modulated
`and scanned as in the simple black and white display.
`Immediately after the scanner the beam is deflected
`into three angularly separated channels in accordance
`with the desired color information. This can easily be
`
`Vizio EX1022 Page 0008
`
`VIZIO 1017
`
`

`
`SH~O OW
`MASK -----,
`
`B•BWE
`G•GREEN
`R• RED
`
`Fig. 6. A shadow mask and pbosplior screen. Monochromatic
`light is incident upon the screen from the three angularly resolved
`color channels.
`
`accomplished with an acoustooptic device. These three
`channels are then directed so that they arc recombined
`at the screen after passing through a shadow mask as
`shown in Fig. 6. The function of the mask is to ensure
`that light from each channel iUuminates only the appro(cid:173)
`priate colored pho phor.
`In practice, the mask and
`phosphor screen could be made as a single unit so that
`the critical alignment tolerances are built into the
`scree