Abstract: A method and system for enabling a conventional smartphone to read and authenticate an invisible barcode or other invisible insignia printed using an invisible printing ink containing a phosphorescent luminophore, and a software application, without a hardware alteration to the smartphone.

Abstract: A direct-reading stadia rod for use with a laser level includes a flexible tape and a sensing head that is movable therealong. The sensing head includes a keyboard, a movement sensor, a laser beam receiver, and a display. The rod is calibrated with a benchmark elevation by placing the base of the tape on a point of known elevation and moving the sensing head along the tape until it is properly aligned with the beam of a remotely located laser level. With the sensing head fixed at that location on the tape, the benchmark elevation is input using the keyboard. Thereafter, the tape is placed upon a second point of unknown elevation, and the sensing head is incrementally moved until the laser beam receiver again detects alignment with the laser plane. Based on data from the movement sensor indicating the distance moved by the sensing head from the benchmark position, the elevation of the second point is automatically determined and the output displayed.