Impact of surface roughness on laser surface authentication signatures under linear and rotational displacements

Abstract

Laser surface authentication (LSA) is a technique for authenticating optically rough surfaces based on the intensity of diffusely scattered light. The degradation in the LSA signature over linear and rotational displacement is examined. Randomly roughened glass surfaces with roughness amplitudes ranging from 0.4 microm to 3 microm and correlation lengths from 16 microm to 45 microm are examined experimentally, showing that the average size of the surface feature has a negligible impact on the rate of LSA signature degradation. The average size of the surface features is shown to have a greater effect on the fractional intensity of the variations in diffuse light and on the quality of LSA signature match.

Laser speckle photography for surface tampering detection

“…Paper authentication The methods closest to our technique are those developed for speckle-based paper authentication [16,19,5,20,6,18], in which the roughness pattern for individual pieces of paper, and their corresponding speckle, are used as an identifying signature. In one representative method, the paper must be permanently fixed to an elaborate mechanical plate that fits in a magnetic mount, to ensure accurate viewpoint reproduction [18] (p. 92).…”

Static laser surface authentication with low-cost microscope: Tolerances on spatial and angular disturbance

“…Speckle-based paper recognition method has been extensively studied under various conditions such as with moving laser and moving CCD camera [7,13], with static laser and rotating CCD camera [14] and with static laser and static CCD camera [9][10][11]. Authentication systems presented in [7] and [14] both have moving parts which have several disadvantages that they require high precision motor whose consistency should be accounted at all times.…”

“…We choose to investigate the spatial and angular disturbance because these two disturbances are likely to arise during common usage. Thus, knowing the limit of this system will provide insight into the viability of this system [13,14]. In the rest of this paper, the term "spatial shift" indicates spatial displacement of the paper, and the term "angular shift" indicates change of incidence angle of the laser with respect to the surface of the paper.…”

Optimal sampling and quantization of dynamic speckles for object identification

“…Many artifacts have such a random structure and, hence, laser speckles can be used in optical authentication systems. [1][2][3][4][5][6] Speckles as an authentication key have an advantage in that the relationship between the three-dimensional microscopic structure of an object and a speckle pattern that it produces is hard to model mathematically.…”

“…2,5 In this study, we investigate the identification performance of dynamic speckles under the condition of limited data sizes. Speckle signals are digitized and stored in a computer.…”