Securing information using a digital holographic technique

We propose a data security system that combines the optical encryption and a digital holographic technique. The proposed system enables us to store, transmit, and decrypt the encrypted data digitally. The data is encrypted optically using the double random phase encryption and is recorded as a digital hologram. The optical key, that is, the Fourier phase mask is also recorded as a digital hologram. The encrypted data is decrypted digitally by using the hologram of the optical key. Figure 1 (a) shows the input images used in the experiments to be decrypted. The electrically reconstructed image is obtained with an input phase mask without the Fourier phase mask. The digitally reconstructed encrypted images are shown in Fig. 1 (b). The image is obtained by inverse Fourier transforming the digital hologram of the encrypted data. The original image cannot be recognized. The digitally reconstructed decrypted images using the hologram of the Fourier phase mask are shown in Fig. 1 (c). Here one can see the original images. The experimental results demonstrate the feasibility of the proposed method.