A virtually optical system with a hierarchical structure is designed for optical verification. At each hierarchical level, two phase-only masks are alternately generated using an iterative approach and then are sparsified. All sparse phase-only masks generated at the lower hierarchical levels are fixed and applied as constraints at the higher hierarchical level. Since sparse phase-only masks are applied for the decoding, the recovered images are invisible and instead can be further verified by a nonlinear correlation algorithm. The results are presented to show validity of the proposed method, and the proposed method provides a promising strategy for optical verification.
"Virtually optical information verification with a hierarchical structure," Optical Engineering 57(1), 010502 (19 January 2018). https://doi.org/10.1117/1.OE.57.1.010502
. Submission: Received: 17 September 2017; Accepted: 28 December 2017
Received: 17 September 2017; Accepted: 28 December 2017; Published: 19 January 2018