A voltage detector and its connected focusing system for voltage measurements on integrated circuits by laser induced photoemission are presented. The capabilities of the system are analyzed theoretically and verified experimentally. Application to metal lines of submicrometer width and spacing is possible, combined with picosecond time resolution and a voltage sensitivity far exceeding that of electron beam probing. An excellent insensitivity to static crosstalk perturbations is demonstrated. Voltage contrast measurements and measurements of photoemission spectra have also been performed with this system.