Phase encryption of biometrics in diffractive optical elements

Abstract

A new technique for the optical encoding of images is presented. The method of generalized projections is used to design diffractive optical elements for the phase encryption of biometrics for security applications. The encryption algorithm converges rapidly, and the decryption is seen to be secure and tolerant to additive noise.

Phase retrieval algorithms: a personal tour [Invited]

“…One can design a diffractive optical element that allows for the encryption of data for security applications [37]. The problem involves jointly designing two diffractive elements having quasi-random phases, with finite pupils, that together reconstruct an image although neither diffractive element by itself gives any hints as to what is in the image.…”

Full-phase photon-counting double-random-phase encryption

“…Since A cosπf ph full x and A sinπf ph full x are both normally distributed [Eqs. (23) and (24), respectively], the quantity inside the arctan· function is the quotient of two independent normally distributed random variables, which is a Cauchy distribution [37]. This can be written as sinπf ph full cosπf ph full ∼ N0;σ 2 2;full N0;σ 2 1;full Cauchy 0;σ 2;full σ 1;full ;…”

“…These include using a full-phase processor [4], applying the DRPE in the Fresnel domain [5], or incorporating the DRPE with digital holography [6]. Moreover, the DRPE has had applications in data storage [20][21][22] and biometrics [23,24]. In [19], Pérez-Cabré et al proposed an additional layer of security to the amplitude-based DRPE by applying photon-counting (PC) to the encrypted image, generating a photon-limited image.…”

Phase-retrieval algorithms applied in a 4-f system for optical image encryption: a comparison

“…However, it is more significant to retrieve all these three phase functions if possible. The first contribution was made by Johnson and Brasher, 14 and successionally a similar algorithm was also introduced recently. 18 These two versions nearly share the same philosophy except that more design freedom is available in the latter implementation because window functions in both the input and the frequency domains are not employed.…”