Abstract: Method to extract timing diagrams from synchronized single- or two-photon pulsed LADA by spatially positioning the incident laser beam on circuit feature of interest, temporally scanning the arrival time of the laser pulse with respect to the tester clock or the loop length trigger signal, then recording the magnitude and sign of the resulting fail rate signature per laser pulse arrival time. A Single-Photon Laser-Assisted Device Alteration apparatus applies picosecond laser pulses of wavelength having photon energy equal to or greater than the silicon band-gap. A Two-Photon Laser-Assisted Device Alteration apparatus applies femtosecond laser pulses of wavelength having photon energy equal to or greater than half the silicon band-gap at the area of interest. The laser pulses are synchronized with test vectors so that pass/fail ratios can be altered using either the single-photon or the two-photon absorption effect. A sequence of synthetic images with error data illustrates timing sensitive locations.