1.2
1-11
1.2.8 Vibration
The floor vibration of the installation site should be measured prior to installing the SU8700.
When the measured values are satisfied Table 1-2-2, no image trouble will occur.
When the instrument is installed on the location in a reinforced concrete or steel frame building
and satisfies the table value, generally effect of vibration will be minimized.
● No vibration source such as large mechanical tools in vicinity
● No vibration source such as public transportation (such as train)
● Installation location is not the first floor
Table 1-2-2 Allowable vibration
The allowable amplitude is determined so that image deviation will not exceed 0.2 mm on a
micrograph taken at a magnification of x220,000 of photo data (127 x 95 mm).
Figure 1-2-1 shows the relation between the frequency of floor vibration and the vibration
transmittance of the instrument. The vibration transmittance is maximum at the resonance
point (approximately 1.6 Hz) of the anti-vibration mount incorporated in the instrument.
Therefore, the allowable amplitude is minimum at this point.
NOTE: ● The waveform of the vibration is a sine waveform. If it is other than a sine
waveform the frequency components will become concentrated in the dominant
frequency.
● For the ultra-low frequency vibration of less than 1 Hz sufficient vibration
dampening cannot be attained with the technology available today.
● The 1 Hz to 10 Hz area is interpolated with the direct lines that tie the tolerance
values.
● If floor vibration exceeds the allowable value, please consult Hitachi individually
(In case of assuming the vibration problems, measure the vibration in advance).
● The above-mentioned allowable vibration is measured with a 15 mm of specimen
size. The larger specimen, the more susceptible to the effect of vibration and the
lower the allowable amplitude.
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