Photographic film has commonly been exposed by a single-photon absorption m
echanism. We determine the conditions for film exposure by direct two-photo
n absorption. Using subpicosecond laser pulses, we find that two-photon exp
osure for commercial film has a threshold fluence and an intensity of 0.000
8 J/cm(2) and 0.0066 TW/cm(2), respectively, well below the optical damage
threshold. Multiphoton photography has the potential for higher spatial res
olution and affords an opportunity for three-dimensional image storage. (C)
1999 Optical Society of America [S0740-3224(99)00304-5] OCIS codes: 190.41
80, 110.5200.