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Miniature random-access fiber scanner for in vivo multiphoton imaging
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View: Figures


Image of FIG. 1.
FIG. 1.

(Color) Schematic cross-sectional drawings of (a) scanner, lenses, mirrors, as well as the excitation (red) and fluorescence (light green) light paths in the microscope head piece; the piezolever fiber scanner (PLFS) in more detail (b), shown in the undeflected (solid lines) and the deflected (dashed lines) state; the unfolded excitation path (c).

Image of FIG. 2.
FIG. 2.

(Color) Bending modes and modeling results: the scanner cross (a) with the actuated and the transverse cross connects. Distortions of the actuated (b) and transverse (c) cross connects and of the scan-fiber section (d) between anchor and cross in more detail. Note, in particular, the back bending of the optical fiber (exaggerated here for better visibility by increasing about 3 times). Deflection (e) of the fiber tip as a function of the attachment-point distance. Scan fiber and connection elements are fused silica and are and in diameter, respectively. The piezo-to-piezo cross-connect length is 3.3 mm. Trimorph parameters are: blocking force and free deflection.

Image of FIG. 3.
FIG. 3.

(Color) (a) The scanner housing (left) of the PLFS with the base with piezobending elements (right). Prototype (b) of the assembled head-mount microscope placed on a 25.4 mm diameter mirror, which serves as size reference.

Image of FIG. 4.
FIG. 4.

(Color) Dynamic response of the scanner: (a) Frequency response for one axis, the peaks at 800 Hz, 5 kHz, and 14 kHz are the resonances (, , and ) of the free fiber end. The peaks and correspond to the first and second order resonance frequencies of the piezobending elements and might be due to cross-connect resonances. Responses (b) to driving the and piezos, respectively. Drive signals and scanner response during image scanning for the fast (c) and slow (d) scan directions. Step response (e) measured using a position-sensitive detector. For (c), (d), and (e) the drive voltage was filtered at 200 Hz with an 8-pole Bessel filter.

Image of FIG. 5.
FIG. 5.

Images of fluorescent beads embedded in agarose: Scanning without low-pass filtering the scan signal (left) leads to stripes of varying bead density (the stripes are about 1.2 ms apart, which is consistent with a resonance frequency of 790 Hz). When low-pass filtering the scan signal (right) the stripes disappear but note the additional distortions at the sides of the image, presumably due to the slowed turnaround.

Image of FIG. 6.
FIG. 6.

(a) Full field image (full scan range, 512 pixels) of neurons in cultured hippocampal slices that were bulk-loaded with Oregon Green, AM. Subfield scanning at of full voltage with different offset positions (, , see supplementary information for full image sequence). All images are averages of 5 frames. The laser intensity after the objective was 80 mW. Note that there are some vibration artifacts visible in the images, which result from the fact that for these measurements the microscope head piece was mounted on a long mechanical arm. The focal plane was roughly below the slice surface. Images (d) and (e) were taken with and without rotation of the scan raster by using fluorescent beads embedded in agarose as test sample. (f) GFP expression in neurons from organotypic hippocampal slices. Spinelike protrusions are visible.


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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Miniature random-access fiber scanner for in vivo multiphoton imaging