JEOL JSPM-5200 Instructions Manual page 301

５ MEASUREMENT OPERATION
• PLL C
Frequency detection in the FM mode is executed in the frequency-d
of AFM AMP using PLL (Phase Locked Loop). Specify parameters for frequency
detection.
• Locked Center Frequency/kHz
• Phase Shifter
• Polarity Reverse
• Output Amp/V
• Dynamic R
• Loop Gain
5-238
ontrol
Specify the center frequency for frequency detection. The frequency detection
circuit detects th e shift of frequency based upon the frequency specified here.
Usually, enter the value near to that of the resonance frequency (peak fre-
quency) of the cantilever.
The Phase Shifter slider enables you to control the phase, which can be set in
the range of ± 130°. Set the Phase Shifter so that the RMS sign
the cantilever) becomes a maximum under the
set to the resonance fr equency of the cantilever
Usually, the Phase Shifter circuit cannot uniformly rotate the phase by 360° i
its characteristics but always has discontinuous point somewhere in control.
The Phase Shifter installed on the AFM amplifier resolved this problem by re-
versing the po larity of phase detection. If this check box is checked, the phase
rotates by 180° from the present angle. Since the operation is performed by the
hardware, the preset value of phase rotation on the software does not change at
all.
Specify the voltage amplitude of the oscillation signal to the cantilever. Oscil-
lation voltage i he FM mode is much smaller than that in the AC mode. n t
ange
Specify the dynamic rang
tion circuit. If the dynamic range is small, the detection sensitivity b
better. However, the detectable frequency amplitude becomes smaller
dynam ic range is large, the result will be reversed. If you select Range 1 in the
Dynamic Range selection box, the dynamic range will be the smallest. If you
select Range 4 in the Dynamic Range selection box, the dynamic range will be
the largest.
Range1: Range width ７６ Hz
Range2: Range width ７６ Hz
Range3: Range width 305 Hz
Range4: Range width 610 Hz
Specify the loop gain in the PLL movement. If the dynamic gain is the same,
the smaller loop gain set in the Loop Gain selection box will improve the re-
solving power for detecting the frequency. Usually, set the Loop Gain as fol-
lows:
Dynamic range Range1:
Dynamic range Range2:
Dynamic range Range3:
Dynamic range Range4:
condition that t
.
e (frequency detection range) of the frequency detec-
Recommended Loop Gain 30
Recommended Loop Gain 20
Recommended Loop Gain 10
Recommended Loop Gain 5
etection circuit
al (amplitude of
he frequency is
n
ecomes
. If the
TMPM5200-2