Dynamic distortion in resonant galvanometric optical scanners

Abstract

High-speed optical systems are revolutionizing biomedical imaging in microscopy, DNA sequencing, and flow cytometry, as well as numerous other applications, including data storage, display technologies, printing, and autonomous vehicles. These systems often achieve the necessary imaging or sensing speed through the use of resonant galvanometric optical scanners. Here, we show that the optical performance of these devices suffers due to the dynamic mirror distortion that arises from the variation in torque with angular displacement. In one of two scanners tested, these distortions result in a variation of signal-to-noise (Strehl) ratio by an order of magnitude across the field of view, degrading transverse resolution by more than a factor of 2. This mirror distortion could be mitigated through the use of stiffer materials, such as beryllium or silicon carbide, at the expense of surface roughness, as these cannot be polished to the same degree of smoothness as common optical glasses. The repeatability of the dynamic distortion indicates that computational and optical corrective methods are also possible.

Suppression of Subpixel Jitter in Resonant Scanning Systems With Phase-locked Sampling

“…Multiple sources of jitter are known to affect resonant scanning imaging which we group into three main categories: 1) mirror jitter, 2) feedback jitter, and 3) synchronization jitter. Mirror jitter is attributed to the mechanical instability of the mirror due to physical factors such as inertial effects [ 30 ], [ 31 ], vibrations [ 31 ], or thermal drift [ 31 ]. Feedback jitter is due to the limitation on how accurately the scanner position can be tracked electronically and has traditionally been addressed by tracking the mirror position optically [ 23 ][ 24 ].…”

Acousto-optic Scanning Spatial-switching Multiphoton Lithography

“…However, serial scanning MPL is unfortunately too slow to be a valuable solution for many practical applications. Although attempts at multi-foci parallelization increase the printing throughput of the scanning MPL, the printing speed is still limited by the inertia of the scanning mirrors [36][37][38][39], and it can only print periodic structures [28,[40][41][42][43][44], resulting in a loss of nanomanufacturing flexibility. Therefore, it remains a serious challenge to take advantage of both scanning and projection methods while avoiding their shortcomings to achieve arbitrary complex 3D structures with high throughput, high accuracy, and broad material applicability.…”

Towards distortion-free imaging of the eye

“…Major distortion also arises when imaging over an extended field, due to the typically flat shape of detectors compared with the highly curved retina. Static distortions can also occur for raster systems employing resonant scanners due to error in the desinusoiding process [ 20 ]; from systematic errors of the hardware [ 21 ]; or from eye movement patterns such as nystagmus which are large, repeatable and potentially have periodicity similar to the imaging frame rate such that pseudo-static distortion could result.…”