SmarAct PICOSCALE, Руководство пользователя

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4 BASIC CONCEPTS
4.3 Signal flow
The PICO SCALE signals can be divided into three categories: optical signals, analog electrical
signals and digital signals. The basic and simpli fi ed signal fl ow is shown in fi gure 4.2.
Figure 4.2: Signal fl ow in the
PICO SCALE
.
At the beginning, an optical signal (light) is generated by a wavelength stabilized DFB laser diode.
The infra-red light is phase modulated with a frequency of
ω
=
30 MHz and sent to the three sensor
heads. The interferometric signals generated in the sensor heads are detected by photo detectors
and converted into electronic signals.
The individual photo-electric signals are demodulated by both the modulation frequency and its
second harmonic (60 MHz). The resulting demodulation signals are digitized by analog-to-digital
converters (ADCs).
The digital signals are used to perform the position calculation. After appropriate fi ltering, the data
stream is con fi gured and the data are transferred to the user PC. You can select the desired data
sources and display them in graphs. Finally, the data can be exported to csv- fi les to be available
for data post-processing.
NOTICE
The position values, generated in the FPGA, have a resolution of 1 pm. Thus, all
internal modules, especially the Advanced Trigger System and the Calculation
System, process integer numbers with the unit picometer.
25 PicoScale User Manual