Abstract
We have been studying a method of information hiding inside an object fabricated with a resin material using a 3-D printer by forming pattern inside the object that expresses information. In this report, we report the new method of forming an internal pattern with a near infrared fluorescent resin material in order to improve the accuracy of reading embedded information. In this method, when an object is irradiated with near-infrared light of a specific wavelength that excites the fluorescent resin material, the fluorescent resin emits light at a wavelength different from that of the excitation light. Therefore, if only the light emitted by the fluorescent material is used for capturing near infrared image by using the optical filter, only the image of the pattern embedded in the object can be captured, and information reading with high accuracy can be expected. Using a fused deposition-modeling 3-D printer with two nozzles, the main body of an abject was formed with one nozzle using ABS resin, and the other nozzle formed an internal pattern with ABS resin containing fluorescent dye. We confirmed that clear images of internal patterns could be captured and the effectiveness of this method was demonstrated.
