Abstract: A device for detecting and determining deformations on a structure surface containing diffractive stress indicator elements comprises a portable computing device having a camera, a processor, a memory, and a display screen, and a casing for conformably enclosing the portable computing device. In one embodiment, the casing includes an elongated light source, a first window positioned to provide access to the display screen of the portable computing device, and a second window positioned to allowing the light source to emit a band of light outside of the casing, and a port hole aligned with the camera of the portable computing device. When the device is positioned proximate to the structure, the elongated light source emits a band of illumination onto the diffractive stress indicator elements, the diffractive elements diffract the emitted radiation and the camera of the portable computing device receives at least a portion of the diffracted radiation.