In many laser scan engines, mechanical inertia imposes a tradeoff between mirror diameter (mass) and scan speed (cycle time) and/or scan angle amplitude. Ultimately, this limits the field-of-view and/or scan speed in multiphoton and confocal imaging, laser-based manufacturing, and other applications. To push parameters past this inertia limit, we present a non-inertial (stationary) add-on unit that doubles the scan angle amplitude while preserving both the beam size and cycle time, thus doubling the étendue (optical invariant) and overall system throughput. We demonstrate its use in two-photon calcium imaging of neural activity in living mice. We also adapt the approach to present a phase-doubling unit that doubles the maximum range of phase modulators. Finally, we describe further variants, including generalizing the approach to Nx scan angle multiplication (N=2,3,4,…) with diffraction-limited performance across a wide scan angle range and over a broad wavelength bandwidth. These non-inertial scan angle multipliers (called Nisam2x, 3x,…) fundamentally break the inertia-imposed tether between scan speed and scan angle amplitude, enabling expanded capabilities of a range of technologies, including imaging, adaptive optics, sensing, marking, and manufacturing.
Yu et al. (Mon,) studied this question.