Two-photon exposure of photographic film

Photographic film has commonly been exposed by a single-photon absorption mechanism. We determine the conditions for film exposure by direct two-photon absorption. Using subpicosecond laser pulses, we find that two-photon exposure for commercial film has a threshold fluence and an intensity of 0.0008 J/cm2 and 0.0066 TW/cm2, respectively, well below the optical damage threshold. Multiphoton photography has the potential for higher spatial resolution and affords an opportunity for three-dimensional image storage.