Agile scanning using a MEMS focus control mirror in a commercial confocal microscope

Abstract

We present the use of a large stroke deformable membrane mirror for focus control over a range of 123 µm in a commercial confocal microscope at 0.5-0.64 NA. The MEMS mirror is much faster than lens or stage translation allowing synchronization to x-y scanning for agile control over the 3D shape of the surface that is scanned. We describe a novel, low-actuator-count MEMS mirror designed specifically for focus control in scanning laser microscopes and present images taken with the mirror deployed on an Olympus Fluoview FV300.

Four-zone varifocus mirrors with adaptive control of primary and higher-order spherical aberration

“…Figure 2 illustrates the fabrication process for the mirrors, which has been previously described in detail [5]. The thin SU-8 membrane is spin coated and photopatterned to create small 4 μm diameter etch vias.…”

“…As an alternative to translating lenses, investigators have explored variable-power optical elements that can be controlled electronically. Varifocus lenses have already been demonstrated in microscopy [1–5], ocular adaptive optics [6,7], cameras [8–11], astronomy [6,12,13], optical interconnects [14–16], pulse compression or shaping [17–19], optical data storage [20–23], micromachining [24,25], and optical tweezers [26]. Active optical elements include deformable membrane mirrors [9,27–33], liquid-filled lenses [34–41], and spatial light modulators [42–44].…”

“…The surface-micromachining process uses an array of small vias in the membrane and xenon difluoride (XeF 2 ) gas to etch the silicon below the membrane, which results in a non-uniform air gap underneath. To mitigate this issue, we recently developed a novel mirror design utilizing a single silicon-on-insulator (SOI) wafer [5]. The top “device” silicon is used as a sacrificial layer, and the buried oxide layer serves as a vertical etch stop to define a uniform air gap across the device.…”

Range Extension of a Bimorph Varifocal Micromirror Through Actuation by a Peltier Element

“…This was highlighted by Dickensheets [1] with focus on confocal microscopy and optical coherence tomography (OCT). In confocal microscopy the use of a VFM [2], [3] or a tunable microlens for focal adjustments has been reported [4]. A confocal laser scanning endoscope was demonstrated using a VFM with scanning capability [5].…”

Dynamic performance of microelectromechanical systems deformable mirrors for use in an active/adaptive two-photon microscope

“…[12][13][14] Compared to mechanical means of focusing that translate the objective lens or the sample, focusing by modifying the wavefront curvature using an MEMS mirror introduces no vibrations and can be accomplished at much higher speeds. This opens up the possibility of imaging along oblique sections or more convoluted surfaces, and for multidepth imaging within a single image frame.…”