Axial scanning in multiphoton microscopy (MPM) is typically
realized
by mechanically shifting either the objective or the sample. However,
the scan speed is usually hindered by the mechanical inertia of the
bulky mass. Although the extended depth of field provided by the non-diffracting
beam allows fast volumetric imaging, it abandons the axial resolution.
Here, we demonstrate a novel and powerful tomographic technique using
the Bessel droplet in MPM, termed tomographic-encoded multiphoton
(TEMP) microscopy, for structural illumination in the axial direction.
We show that benefiting from the high-order nonlinear excitation in
MPM, the side-lobe cancellation and smaller beam focus of the Bessel
droplet realize better image quality. TEMP microscopy allows fast
axial scanning, less risks of photodamage and photobleaching, and
high-resolution and high-contrast imaging. Furthermore, fewer raw
images are required for the 3D image reconstruction. To demonstrate
its usability and advantages for scattering tissues and biomedical
applications, we showcase TEMP microscopy with highly scattering fluorescence
microspheres and mouse brain slice. More details can be visualized
by the Bessel droplet compared with the conventional Gaussian and
Bessel beam. The depth-resolving performance of the Bessel droplet
has an excellent consistency with the Gaussian beam. More importantly,
the TEMP technique is an easy-plug-in method for the current microscopy
system. TEMP microscopy is promising for fast volumetric multiphoton
imaging, especially for highly scattering tissues.