Research on Light Propagation to be Transmitted Across the Heterogeneous Porous Fibers Material (2)

抄録

In last article,¹⁾ we focused on the change of diffuse transmitted light from direct light source which irradiates light perpendicularly to surface of watermark paper and inclined light source which irradiates light inclinedly. In the experiment, we discovered the range where linearity in output ratio is produced as irradiation angle is widened when transmitted light volume of direct light source is regarded as reference. In this article, we confirmed the limiting angle of linearity by increasing transmitted light volume which is incident on receiving section with wider viewing angle of lens. We also confirmed the limiting angle by irradiating light on thinnest area of watermark paper (white part), because the increase of transmitted light volume can be expected in this way, too. As a result, we confirmed that the linearity is extended within signal-to-noise ratio (SN ratio) where light/dark discrimination level is secured. In other words, the range of linearity was already confirmed to approximately 60° of irradiation angle but it is secured up to 70°. Therefore, it is possible to extract the image change of light which is transmitted through fluorescent pattern or polarization surface of watermark part as precise image data by using the irradiation angle in the range with linearity and processing image of watermark pattern which meets transmitted light volume of direct light source.