NLOM is based on the excitation of the non-linear optical response that any material can generate upon excitation with laser pulses of very short duration, in the range of femtoseconds. The NLOM system makes possible, throughout the combined use of the different modalities (Multiphon Excitation Fluorescence, Second and Third Harmonic Generation), to acquire information, in a totally non-invasive way, on the presence of layers of different chemical nature, their thickness or their crystalline or hierarchical internal organization (i.e. parchment, starch glues, etc.). Lateral and axial resolutions are in the micrometre range and the penetration depth can reach up to 1 mm, depending on the sample transparency. The technique can be applied to substrates that are transparent in the IR region, such as varnishes, painting layers, corrosion layers on metal substrates, parchments and others.
corrosion layers, decorative arts, film, manuscript, mosaics, other, painting, papyrus, parchment, photo, sculpture, textile, varnishes
fossil, mineral, other, shell, skeleton
ceramics, glass, stone, metal and metallurgical By-Products, pigment
binding media, glues, varnishes
The NLOM system consists in an upright microscope which uses an ultrashort laser system as excitation light source. The laser is a mode-locked Ti:Sapphire oscillator emitting at 800 nm, delivering 70 femtosecond pulses at a repetition rate of 80 MHz. A variable neutral density filter is used to control the laser power reaching the sample...