An optical detector that can measure the pulse width of a picosecond light pulse from a mode‐locked Nd‐glass laser has been developed. The detector was constructed with seven spatially separated CdS0.5Se0.5crystals which exhibited two‐photon conductivity when illuminated with 1.06 &mgr;m optical radiation. A seven‐channel peak detector and display system were used in conjunction with the two‐photon detector to record picosecond pulses on a single‐shot basis. For the laser used the measured correlation curve yielded a pulse width of 10 ps with a contrast ratio of 2.8:1.