Fig. 5.

Performance of the ultra-large-field-of-view two-photon scanning microscope. (a) Two-photon intensity measurements from a uniform bath of fluorescein and accompanying map of contours of constant intensity. (b) Intensity profiles along the X- and Y-axes of the data in panel a. We further show intensity data obtained with the beam parked on-axis and the objective tilted about an axis in the plane of the back aperture; these measurements provide an upper bound on the intensity attainable with this objective. (c) Experimental measurements of the PSF as a function of scan angle. The color scale for the measured PSFs are all self-normalized. Although this represents a significant deviation from a flat field, the maximal residual beam convergence for the scan system remains relatively moderate, equivalent to a downstream focus of 20 m. (d, e) Plots of the axial and lateral extent of the PSFs. Red and blue data points represent the performance of the system under standard scanning conditions. Green data points are the PSF found by tilting the objective; these represent the objective-limited performance of the system. (f) The measured shift in the height of the focal spot as a function of scan position along with the calculated height based on a residual scan-dependent beam convergence.