An Electrostatic MEMS Translational Scanner with Large Out-of-Plane Stroke for Remote Axial-Scanning in Multi-Photon Microscopy

Haijun Li,Gaoming Li,Thomas Wang,Xiyu Duan,Kenn Oldham

doi:10.3390/mi8050159

Abstract

We present an electrostatic microelectromechanical systems (MEMS) resonant scanner with large out-of-plane translational stroke for fast axial-scanning in a multi-photon microscope system for real-time vertical cross-sectional imaging. The scanner has a compact footprint with dimensions of 2.1 mm × 2.1 mm × 0.44 mm, and employs a novel lever-based compliant mechanism to enable large vertical displacements of a reflective mirror with slight tilt angles. Test results show that by using parametrical resonance, the scanner can provide a fast out-of-plane translational motion with ≥400 μm displacement and ≤0.14° tilt angle over a wide frequency range of ~390 Hz at ambient pressure. By employing this MEMS translational scanner and a biaxial MEMS mirror for lateral scanning, vertical cross-sectional imaging with a beam axial-scanning range of 200 μm and a frame rate of ~5–10 Hz is enabled in a remote scan multi-photon fluorescence imaging system.

Highlights

Optical imaging in vertical cross-sections with sub-cellular resolution is essential to biomedical research and clinical diagnosis because histology-like images can be provided to distinguish different features of tissue for early detection of cancer and other diseases
Axial scanning in confocal and multi-photon microscopes is achieved with the movement of either the objective or stage, and images in the vertical plane are reconstructed from a series of horizontal images
Axial scanning with group velocity dispersion (GVD) modulation can achieve high speeds, but results in blurry images [4]

Summary

Introduction

Optical imaging in vertical cross-sections with sub-cellular resolution is essential to biomedical research and clinical diagnosis because histology-like images can be provided to distinguish different features of tissue for early detection of cancer and other diseases. By combining axial and lateral scanning, this capability can be provided. Axial scanning in confocal and multi-photon microscopes is achieved with the movement of either the objective or stage, and images in the vertical plane are reconstructed from a series of horizontal images. New methods to perform remote axial scanning have been developed to overcome these limitations, including group velocity dispersion (GVD)-based [1–4] and tunable lens-based temporal focusing [5,6].

Results

Conclusion