Understanding the limits of remote focusing

It has previously been demonstrated in both simulation and experiment that well aligned remote focusing microscopes exhibit residual spherical aberration outside the focal plane. In this work, compensation of the residual spherical aberration is provided by the correction collar on the primary objective, controlled by a high precision stepper motor. A Shack-Hartmann wave front sensor is used to demonstrate the magnitude of the spherical aberration generated by the correction collar matches that predicted by an optical model of the objective lens. The limited impact of spherical aberration compensation on the diffraction limited range of the remote focusing system is described through a consideration of both on-axis and off-axis comatic and astigmatic aberrations, which are an inherent feature of remote focusing microscopes. Published by Optica Publishing Group under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

Automated summary

It has been demonstrated that well aligned remote focusing microscopes exhibit residual spherical aberration outside the focal plane, and this study proposes a compensation method using a correction collar controlled by a stepper motor. The study verifies the accuracy of the compensation method using a Shack-Hartmann wavefront sensor, and discusses the limited impact of spherical aberration compensation on the diffraction limited range of the remote focusing system.