The SPM Head is an integrated detector-probe assembly that sits above the scanner-mounted sample. The head and attached XY stage are kinematically mated to the scanner via three contact points. A pair of retaining springs secures the head, allowing it to be raised and lowered using adjustment screws threaded through the scanner body. On older models, two screws are manually adjusted by the operator and the rear-most screw is motorized. Newer, “vertical” scanners use a single-screw motorized adjustment.
Figure 1, below, depicts the optical path of the laser beam inside a MultiMode 8 SPM head.
Figure 1: MultiMode 8 SPM Head and Major Components
The scanner moves the sample underneath the probe tip and generates the cantilever deflection or probe feedback signal for the different imaging modes. A quad photodetector (QPD) in the SPM head detects the beam emitted by the laser diode as it reflects off the cantilever. Figure 2 shows the arrangement of the photodiode elements in the MultiMode 8 head.
Figure 2: Quad Photodetector Arrangement
Key components of the MultiMode 8 SPM head are:
The X and Y laser diode adjustment knobs position the laser beam on the cantilever. The X laser diode adjustment knob moves the beam parallel to the major axis of the cantilever substrate. The Y laser diode adjustment knob moves the beam perpendicular to the major axis of the cantilever substrate. See Align the Laser for more information on using the alignment knobs.
| www.bruker.com | Bruker, Inc. |
| www.brukerafmprobes.com | 112 Robin Hill Rd. |
| http://nanoscaleworld.bruker-axs.com | Santa Barbara, CA 93117 |
| Customer Support: (800) 873-9750 | |
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Photodetector
