| 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 (X<SUB>m</SUB>, Y<SUB>m</SUB>) by encoding the image using e.g. a phase mask with an encoded phase value phi (X<SUB>m</SUB>, Y<SUB>m</SUB>) and an encoded amplitude value a (X<SUB>m</SUB>, Y<SUB>m</SUB>), and by further encrypting the mask (using e.g. a spatial light modulator) by addition of an encrypting phase value phi<SUB>c </SUB>(X<SUB>m</SUB>, Y<SUB>m</SUB>) to the encoded phase value phi (X<SUB>m</SUB>, Y<SUB>m</SUB>) and by multiplication of an encrypting amplitude value a<SUB>c </SUB>(X<SUB>m</SUB>, Y<SUB>m</SUB>) with the encoded phase value a (X<SUB>m</SUB>, Y<SUB>m</SUB>). 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 phi<SUB>d </SUB>(X<SUB>d</SUB>, Y<SUB>d</SUB>) and the decrypting amplitude value a<SUB>d </SUB>(X<SUB>d</SUB>, Y<SUB>d</SUB>) respectively, of a modulator resolution element (X<SUB>d</SUB>, Y<SUB>d</SUB>) being substantially equal to -phi<SUB>c </SUB>(X<SUB>m</SUB>, Y<SUB>m</SUB>) and a<SUB>c</SUB><SUP>-1 </SUP>(X<SUB>m</SUB>, Y<SUB>m</SUB>).
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