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Instrumentation / Graphtec / Vibration /

The sensor unit measures the magnitude of interference (the difference
in frequency) by irradiating the object to be measured with a reference
beam, receiving the reflected light (now Doppler-shifted as a result of
vibration), and O/E-converting the measured magnitude of interference
(light is converted into analog signals).


The sensor head and laser unit, built as one piece, constitute the sensor unit. The
unique aluminum die-cast frame substantially reduces size and improves ruggedness
and ease of use (as compared to more conventional products). These features
combine to provide a high degree of reliability, permitting use in DVD research and
the like, as well as on production lines. Since option fiber is not used, measurement
light and reflected light can be made to interfere very efficiently, thus permitting a high
degree of sensitivity in measurement. In addition, the improved sensitivity of the
AT0023 eliminates previous difficulties in adjusting and setting sensitivity levels


Demodulation Unit

The demodulation unit FM-demodulates signals that have O/E-converted by the sensor unit (i.e.,where
the optical signals have been converted to analog signals), subsequently outputting signals proportional
to the vibration speed of the object of measurement.While the standard function outputs the speed and
frequency of vibration, the differential-integral function (an optional feature that can be incorporated in
the unit)can integrate speed to calculate displacement and differentiate the speed into an acceleration,
outputting the results.


Wide-band demodulation unit


A broad measurement range and a rich variety of applications

The measurement frequency range,from DC to 2 MHz, permits the
measurement of transitional characteristics from a static state,and of uniform
motion and vibration at high frequencies. The measurable speed range is from
0.4m/s to 10m/s(lower limit of speed:5 kHz LPF). The AT3700 thus permits a
broad range of vibration measurements and is applicable to a variety fields.


Various optional features

  • Wide-band demodulation function: Incorporation this in the unit raises the

          upper limit of the measurable frequency range to 10 MHz, rendering an ever
          broader range of measurement possible.

  • Differential-integral function:Incorporating this in the unit makes it possible

          to differentiate speed signals from the Laser Doppler Vibrometer into an
          acceleration and to integrate these into a displacement.


High-sensitivity demodulation unit



Improved sensitivity helps overcome difficult measurement

Measurement sensitivity has been greatly improved:the AT3600 is now twice as
sensitive as before. This high sensitivity provides for convenient vibration
measurement of object that were previously difficult to measure.

Optional differential-integral function

This feature enables the differentiation of speed signals from the Laser Doppler
Vibrometer into an acceleration,and for their subsequent integration into a
displacement(speed,displacement,and acceleration can be output at one time).


AT3700/3600 Optional features

Differential-integral function L-011
This is available for incorporation in the demodulation unit of the Laser Doppler Vibrometer. The L-011integrates
demodulated speed signals into a displacement or differentiates them into an acceleration.

Wide-band demodulation function L-012 (for AT3700 only)
This adds a wide-band demodulation capability to the standard demodulation function. Designed to be incorporated in the
demodulation unit. Expands the measurement frequency range to a maximum of10 MHz at the speed range of 100 [m/s/V],
thereby making it possible to analyze transitional phenomena otherwise unable to be measured with harmonic vibration
measurement or with the standard demodulation function.