title: Markov speckle for efficient random bit generation.
abstract: Optical speckle is commonly observed in measurements using coherent radiation. While lacking experimental validation, previous work has often assumed that speckle's random spatial pattern follows a Markov process. Here, we present a derivation and experimental confirmation of conditions under which this assumption holds true. We demonstrate that a detected speckle field can be designed to obey the first-order Markov property by using a Cauchy attenuation mask to modulate scattered light. Creating Markov speckle enables the development of more accurate and efficient image post-processing algorithms, with applications including improved de-noising, segmentation and super-resolution. To show its versatility, we use the Cauchy mask to maximize the entropy of a detected speckle field with fixed average speckle size, allowing cryptographic applications to extract a maximum number of useful random bits from speckle images.
authors.affiliation: Department of Electrical Engineering, California Institute of Technology, Pasadena, CA 91125, USA. roarke@caltech.edu
authors.forename: Roarke
authors.initials: R
authors.lastname: Horstmeyer
authors.forename: Richard Y
authors.initials: RY
authors.lastname: Chen
authors.forename: Benjamin
authors.initials: B
authors.lastname: Judkewitz
authors.forename: Changhuei
authors.initials: C
authors.lastname: Yang
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D019277:Entropy; D006801:Humans; D007089:Image Enhancement; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008390:Markov Chains; D008954:Models, Biological; D010363:Pattern Recognition, Automated / Q000379:methods*