Poor man's two photon imaging: Scanning Laser Upconversion Microscopy

Two photon microscopy is one of the most powerful techniques for optical images. Its deep penetration, low scattering and mainly its sectioning power allows exquisite control on all three axes of 3D samples, both for imaging and actuation. Unfortunately, this technique involves very expensive femtosecond lasers. Upconverting Nanoparticles display multiphoton absorption at low instantaneous power, which can be achieved by means of cheap laser diodes. Scanning Laser Upconversion Microscopy offers the deep penetration and low scattering of NIR excitation together with the sectioning power of multiphoton techniques for under US$ 1000.