Spm Head; Figure 2.1C Multimode Spm Head And Major Components - Veeco 004-210-000 Instruction Manual

SPM Fundamentals for the MultiMode
Hardware

2.1.2 SPM Head

Figure 2.1c
X-Y stage are kinematically mated to the scanner via three contact points. A pair of retaining
springs hold down 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; the
rear-most screw is motorized and under computer control. Newer, "vertical" scanners use
motorized single-screw adjustment.
Photodiode adjust
Photodiode array—The four elements of the quad photodiode (position sensitive detector) are
combined to provide different information depending on the operating mode. In all modes the four
elements combine to form the SUM signal. The amplified differential signal between the top two
elements and the two bottom elements provides a measure of the deflection of the cantilever. This
differential signal is used directly in the contact AFM. It is fed into an RMS converter (or phase
module if attached) for TappingMode operation. Similarly, the amplified differential signal between
the sum of two left photodiodes and the sum of the two right photodiodes provides a measure of the
torsion in the cantilever and is used in Lateral Force Microscopy (Image data type: Friction).
Figure 2.1d
segments of the photodetector are used for generating AFM and LFM signals.
20
below shows a MM-SPM head with various adjustment knobs. The head and attached

Figure 2.1c MultiMode SPM Head and Major Components

Laser Y-axis adjust
Head X-axis stage adjust
shows the arrangement of the photodiode elements in the MultiMode head. Different
MultiMode SPM Instruction Manual
Laser X-axis adjust
Head Y-axis stage adjust
KEY
1. Laser
2. Mirror
3. Cantilever
4. Tilt Mirror
5. Photodetector
Rev. B