Line-temporal focusing has been recognized as an elegant strategy that provides two-photon microscopy with an effective means for fast imaging through parallelization, together with an improved resilience to scattering for deep imaging. However, the axial resolution remains sub-optimal, except when using high NA objectives and a small field-of-view. With the introduction of an intracavity control of the spectral width of the femtosecond laser to adaptively fill the back aperture of the objective lens, line-temporal focusing two-photon microscopy is demonstrated to reach near-diffraction-limited axial resolution with a large backaperture objective lens, and improved immunity to sample scattering. In addition, a new incoherent flattop beam shaping method is proposed which provides a uniform contrast with little degradation of the axial resolution along the focus line, even deep in the sample. This is demonstrated in large volumetric imaging of mouse lung samples.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics