Correction of dynamic aberration in resonant optical scanners using tilted optics

Abstract

Mirrors in resonant galvanometric optical scanners experience dynamic distortion due to torque which is proportional to angular displacement. The dominant aberration introduced by the sinusoidal oscillation of the scanner is oblique astigmatism that is linear with the field coordinate. Nodal aberration theory (NAT) indicates that such linear astigmatism can be compensated by tilting elements with power in an optical system. Here, we demonstrate a practical and low-cost solution that only requires tilting of existing optical elements immediately following the resonant scanner. The proposed method can be used to generate any desired third-order aberration that results from tilting or decentering optical surfaces in optical systems. This is illustrated by correcting linear astigmatism due to a resonant scanner by tilting elements in reflective and refractive afocal relays. In all cases, wavefront correction better than the classical diffraction limit (Strehl ratio > 0.8) was demonstrated.