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Instrumentation

The Microscope Body

The operation of a microscope in UHV, at low temperatures, and in strong magnetic fields requires non-magnetic, UHV-compatible materials, which should have a similar thermal expansion over the whole temperature range. These properties are almost perfectly fulfilled by the used combination of the piezoelectric material lead zirconate titanate, macor and titanium.

A photo and a schematic cross section of the microscope can be seen in the figure above. To keep the microscope as rigid as possible, the main body is made out of one piece of macor. It has a cylindrical shape of 125 mm in length and 58 mm in diameter. The fixed cantilever stage is located in the middle of the macor body. The upper part hosts the piezoelectric scanner for the sample and a piezoelectric stepper motor for coarse approach. Samples are mounted on a small titanium plate, which can be inserted into the sample holder. It is held on the sample scanner by two springs. Scan ranges are 18 µm x 25 µm at 300 K, 15.5 µm x 18 µm at 78K, and 7.5 µm x 7.5 µm at 5.2 K. For lateral coarse positioning within an area of 2 mm x 2 mm of the sample, an xy-table is implemented in the microscope, which uses a two axis piezoelectric stepper motor.

The lower part of the microscope contains the fiber optic interferometer for the detection of the cantilever deflection. It allows a very compact and rigid design. At the same time it is a very sensitive method. For coarse adjustment of the fiber a piezoelectric stepper motor is used, while the fine adjustment is accomplished by a piezoelectric scanner unit.

Read more about thermal anchoring of the microscope.

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