Two-step phase-shifting interferometry and its application in image encryption

Abstract

Conventional phase-shifting interferometry (PSI) needs at least three interferograms. A novel algorithm of two-step PSI, with an arbitrary known phase step, by which a complex object field can be reconstructed with only two interferograms is proposed. This algorithm is then applied to an information security system based on double random-phase encoding in the Fresnel domain. The feasibility of this method and its robustness against occlusion and additional noise attacks are verified by computer simulations. This approach can considerably improve the efficiency of data transmission and is very suitable for Internet use.

Phase Shifting Holography for THZ Near-Field/Far-Field Prediction

“…Collecting real and imaginary parts in (6) dictates that simultaneously γ = (1 + ατ 2r ) and γ = −jατ 2i thus leading to α = −1/τ 2 and hence…”

“…It is shown that when the reference wave is sufficiently strong a condition C is met [6], and then only two holograms are required (C2H). However, in this case an entire scan of the AUT near-field intensity is needed to determine the minimum reference level.…”

Optical Encryption Scheme with Multiple Users Based on Computational Ghost Imaging and Orthogonal Modulation

“…Especially since the double random-phase encryption method [1] was proposed, all kinds of random-phase encoding (RPE) schemes based on diffraction or interference principles have been booming [2][3][4][5][6][7][8][9][10][11][12][13]. As the accompanying complementary opposites, the corresponding security analyses have also been carried out and have promoted the further development of optical encryption techniques [14][15][16][17][18].…”

Single-step method for fiber-optic probe-based full-range spectral domain optical coherence tomography

“…They can be categorized into the multi-and single-frame methods. As the multi-frame method, the phase shifting [5][6][7][8][9][10] and the simultaneous multiple detection method [11,12] were researched. For the single-frame method, the BM scan [13] (B-scan: lateral scan, M-scan: reference mirror scan), the B-scan-based Hilbert transform reconstruction [14], and the phase shift between two A-lines [15] methods have been proposed.…”

“…However, it requires several interferograms at the same location to build a single complex A-line, which is time consuming; the two-step phase-shifting method has been adopted particularly because it demands just two interferograms [6,7,9,10]. By utilizing multiple spectrometers [11] or a 3 × 3 coupler [12] for parallel detections, two interferograms of a phase difference could be simultaneously captured.…”