JEOL JSPM-5200 Instructions Manual page 299

５ MEASUREMENT OPERATION
FM tab window
Whe n performing measurements in the FM mode, specify the parameters for cantilever
oscil lation.
• High A
This chec
tab
cant
difficult to oscillate.
• PLL Excitation
Set the oscillation-excitation method of the cantilever when you perform FM
measurement. When the scanning speed is rapid, or the specimen surface is topog-
raphical, check the PLL Excitation box for measurement.
Though self oscillation-excitation of the cantilever (oscillation in the resonance
frequency) is used in ordinary oscillation-excitation, the cantilever comes into
contact with the specimen surface during scanning and its oscillation stops, since its
amplitude is very small.
When PLL Excitation is checked, the ordinary self oscillation-excitation of the
cantilever changes to oscillation-excitation by the oscillator installed in the PLL
(Phase Locked Loop) circuit. Then even if oscillation stops when the cantilever
comes into contact with the specimen surface, re-oscillation of the cantilever will be
easier due to the excitation of the PLL oscillator. Since the PLL oscillator tries to
maintain the values that have been set to the frequency and phase, the principle
involved is essentially the same as in ordinary self oscillation-excitation.
When you have changed the PLL Excitation after you had once finished adjusting
the FM measurement, the oscillation conditions of the cantilever change. So you
must readjust the FM measurement.
5-236
mplitude
k box has the same function as the OSC On check box on the AC/Phase
window. This is used in such case as require high voltage to oscillate the
ilever when you observe a specimen in a liquid or use a cantilever that i s
TMPM5200-2