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    5.
    发明专利
    未知

    公开(公告)号：DE1774471A1

    公开(公告)日：1972-02-17

    申请号：DE1774471

    申请日：1968-06-28

    Applicant: IBM

    Inventor： FALLS WAPPINGERS

    IPC: G11C13/04

    Abstract: 1,160,048. Read-only stores. INTERNATIONAL BUSINESS MACHINES CORP. 28 May, 1968 [14 July, 1967], No. 25424/68. Heading G4A. A data store uses an interference pattern, data being distinguished by bandwidth. An optical read-only store uses a Lippmann photographic plate in the thickness of which spaced reflecting layers have been established by setting up standing waves of light, developing and fixing. An electro-optical digital light deflector is used for selecting a storage position at which a 5-bit word is recorded using wide and narrow ranges of wavelengths (centred on the same wavelength) for bit-values 0 and 1 respectively, the ranges relating to different bit positions being non-overlapping in the frequency spectrum. A shutter, and rotatable disc bearing 5 x 2 bandpass filters, are used in recording. On read-out, a Fabry-Perot multibandpass filter (two spaced partially-reflecting films) passes a range of wavelengths (of light reflected from the photographic plate) at each bit position in the frequency spectrum which includes part of the " 0 " range but essentially none of the "1" range, a prism then frequencyanalysing the light on to a line of five photocells. Alternatively, for read-out, a Michelson interferometer produces interference fringes from essentially only the "1" bits, by suitable choice of the path-difference in the interferometer. The fringes are diffused by a groundglass screen and then frequency-analysed by a lens system on to a line of five photo-cells. Use of holography and Lippmann holography are mentioned as alternatives.

    7.
    发明专利
    未知

    公开(公告)号：DE1298218B

    公开(公告)日：1969-06-26

    申请号：DEJ0028448

    申请日：1965-06-26

    Applicant: IBM

    Inventor： MAX ,  ERHARD DR ,  M KOSANKE KURT ,  FALLS WAPPINGERS ,  KULCKE ,  W DR WERNER

    IPC: G02F1/09 ,  H01S3/105 ,  H01S3/10

    Abstract: 1,053,086. Lasers. INTERNATIONAL BUSINESS MACHINES CORPORATION. May 21, 1965 [June 29. 1964], No. 21755/65. Heading H1C. A laser has its optical cavity formed by mirrors 11, 12 of magnetic material one of which is partially transmitting, the mirrors being controllably magnetized so that the Kerr magneto optical effect causes an output ray circularly polarized in a selected direction to be obtained. The active medium may be dysprosium-doped calcium fluoride which radiates circularly polarized light when pumped and subjected to a magnetic field, or may be another medium the radiation of which is circularly polarized by quarter wave plates 14, 15. When the magnetic field applied to a mirror 11, 12 is in the same direction as the incident radiation, Fig. 1 (not shown), the reflected light becomes more strongly polarized in the right-hand sense. The converse applies when the direction of the magnetic field is reversed, Fig. 2 (not shown). The laser may be arranged so that the threshold for laser action is only exceeded if both mirrors produce circular polarization in the same sense. Then by reversing the magnetization of both mirrors the direction of circular polarization of the output light is reversed. Other relationships of magnetic directions in association with an optical cavity of higher Q can be used. In a modification one mirror is formed of a dielectric material having a constant reflectivity irrespective of the polarization direction. An output is then obtained which is circularly polarized in one direction or the other in accordance with the magnetization direction of the single mirror. By controlling the magnetization of the mirrors a modulated output may be obtained.

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