The invention provides a method for manufacturing a waveguide which increases the image distortion between the original and damaged image. This significantly increases the difficulty in deducing the initial PUF value from a damaged image. The technology employs a novel two-color phosphor-loaded waveguide technology. When an invasive attempt is made on the system, not only is the image distorted, but color sensitive phosphor is also activated causing a color change in the system. The device can be applied to systems after full fabrication, allowing the security systems of manufactured electronics to be upgraded.