Application Cases

Experiment Name: Application of Power Amplifier in Absolute Measurement of Micro-Vibration Using Fiber Optic White Light Interferometry

Research Direction:
Interferometric fiber optic vibration sensing. A dynamic measurement technique for fiber optic white light interferometry based on the principle of compressed sensing (CS-WLI) is proposed. The time-varying interference spectrum of the Fabry-Perot vibration sensor is considered a two-dimensional (2D) signal with respect to laser wavelength and time, enabling compressed sampling during the measurement process using a programmable semiconductor laser. The spectral sampling rate after CS reconstruction equals the random wavelength modulation frequency. Nanoscale vibration experiments validated the effectiveness of this approach.

Test Objective: To verify the effectiveness of the proposed compressed sensing fiber optic white light interferometry technique and achieve high-precision all-fiber vibration monitoring.

Testing Equipment: Signal generator, ATA-105 power amplifier, piezoelectric ceramic transducer, programmable fiber optic laser interferometry demodulator

Experimental Content:
A low-finesse Fabry-Perot interferometric cavity is formed between the fiber end face and a piezoelectric ceramic coated with a gold mirror. The sinusoidal signal generated by the signal generator is amplified by the Aigtek ATA-105 power amplifier and applied to the piezoelectric ceramic transducer, driving it into high-frequency vibration. Unlike conventional linear wavelength scanning in fiber optic white light interferometry, this approach employs a programmable laser for random wavelength sampling. The interference spectrum at each sampling point is reconstructed using a compressed sensing reconstruction algorithm, allowing the absolute cavity length of the Fabry-Perot interferometer to be demodulated.

Experimental Procedure:
As shown in Figure 1, the signal generator outputs a 20 kHz sinusoidal signal, which is amplified by the ATA-105 power amplifier and applied to the piezoelectric ceramic transducer, driving it to vibrate at the same frequency. The modulated grating Y-branch laser is subjected to rapid, discrete wavelength modulation at a wavelength switching speed of 500 kHz according to a random wavelength sequence embedded in the laser driver module, while the corresponding interference light intensity is synchronously acquired. The compressed sampling interference spectral data collected over a period are shown in Figure 2.

Test Results:
Based on the compressed sensing principle, the spectral data acquired in Figure 2 were reconstructed to obtain the time-varying two-dimensional spectrum shown in Figure 3. A complete reconstructed spectrum is obtained at each sampling time point. Figure 4 shows reconstructed interference spectra at three different time points. Using these interference spectra and conventional white light interferometry cavity length demodulation algorithms, the absolute cavity length of the Fabry-Perot cavity can be derived. The cavity length waveform is shown in Figure . This approach enables all-fiber, non-contact high-frequency vibration measurement, and the application of compressed sensing significantly improves the spectral sampling rate.

Figure: ATA-100 Series Power Amplifier Specifications and Parameters