Compact module for video-rate image mosaics in two-photon microscopy

Biological applications using multiphoton microscopy increasingly seek a larger field of view while maintaining sufficient temporal sampling to observe dynamic biological processes. Multiphoton imaging also requires high numerical aperture microscope objectives to realize efficient non-linear excitation and collection of fluorescence. This combination of low-magnification and high-numerical aperture poses a challenge for system design. To address this, the use of a liquid crystal polarization grating stack is proposed here to temporally sequence through multiple fields of view. This solution pans the native field of view with minimal latency and zero inertial movement of either the microscope or biological sample. Implemented as a simple add-on unit to existing multi-photon microscopes, this device increases the total field size by 4x, covering up to 7.6mm². Performance constraints and functional demonstration of imaging neural activity are presented.