Optical fabrication of 3D scattering medium for secure optical memory card

摘要

We review an optical secure memory card using a three-dimensional (3D) scattering medium and 3D absorbers. The information of 3D absorbers such as position, size, and number can be used as 3D data. The strong scattering effect can make the data secure for measuring them by interferometer. To recover the absorption distribution, a computational method is developed. We show the numerical results of the reconstructed absorption distribution and then show how important to control the scattering coefficient in a volume medium. We also present preliminary experimental results to make a scattering medium by using holes created by irradiation of femtosecond laser pulse.