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    AN OPTICAL ENCRYPTION AND DECRYPTION METHOD AND SYSTEM
    2.
    发明公开
    AN OPTICAL ENCRYPTION AND DECRYPTION METHOD AND SYSTEM 有权
    光端机和解码系统

    公开(公告)号：EP1093689A1

    公开(公告)日：2001-04-25

    申请号：EP99926286.8

    申请日：1999-06-16

    申请人： FORSKNINGSCENTER RISO

    发明人： GLÜCKSTAD, Jesper

    IPC分类号： H04K1/00 ,  G02B27/52 ,  G02B27/46

    CPC分类号： H04K1/00 ,  G02B27/46

    摘要： The invention relates to securing of information utilising optical imaging technologies and more specifically to phase encryption and decryption of images. An image is encrypted into a mask having a plurality of mask resolution elements (Xm, Ym) by encoding the image using e.g. a phase mask with an encoded phase value φ (Xm, Ym) and an encoded amplitude value a (Xm, Ym), and by further encrypting the mask (using e.g. a spatial light modulator) by addition of an encrypting phase value φc (Xm, Ym) to the encoded phase value φ (Xm, Ym) and by multiplication of an encrypting amplitude value ac (Xm, Ym) with the encoded phase value a (Xm, Ym). The method of decrypting comprises the steps of decrypting the mask by radiating electromagnetic radiation towards the mask and inserting into the path of the electromagnetic radiation a complex spatial electromagnetic radiation modulator comprising modulator resolution elements, the decrypting phase value φd (Xd, Yd) and the decrypting amplitude value ad (Xd, Yd) respectively, of a modulator resolution element (Xd, Yd) being substantially equal to -φc (Xm, Ym) and ac-1 (Xm, Ym).

    PHASE CONTRAST IMAGING
    5.
    发明公开
    PHASE CONTRAST IMAGING 失效
    相位衬度成像

    公开(公告)号：EP0830632A1

    公开(公告)日：1998-03-25

    申请号：EP96911939.0

    申请日：1996-04-26

    申请人： FORSKNINGSCENTER RISO

    发明人： GLÜCKSTAD, Jesper

    IPC分类号： G02B27

    CPC分类号： G02B27/52 ,  G03H2001/085

    摘要： The invention relates to a method and a system for synthesizing a prescribed intensity pattern based on phase contrast imaging that is not based on the assumption of prior art methods that the pahase shift ζ is less than 1 radian. An improved method based on a simple imaging operation with a simple one-to-one mapping between resolution elements of a spatial phase modulator and resolution elements of the generated intensity pattern is provided. According to the invention a method is provided for synthesizing an intensity pattern with low loss of electromagnetic energy, comprising spatial modulation of electromagnetic radiation with a spatial phase mask for modulation of the phase of the incident eletromagnetic radiation by phasor values of individual resolution elements of the spatial phase mask, each phasor value being determined in such a way that the values of the Fourier transformed phasors attain predetermined values for predetermined spatial frequencies, and the phasor value of the specific resolution element of the spatial phase mask corresponds to a distinct intensity level of the image of the resolution element in the intensity pattern, and a spatial phase filter for phase shifting of a part of the electromagntic radiation, in combination with an imaging system for generation of the intensity pattern by interference in the image plane of the imaging system between the part of the electromagnetic raidation that has been phase shifted by the phase filter and the remaining part of the electromagnetic radiation.