Application Cases

Experiment Name: Dynamic Stress Testing of MEMS

Test Equipment: Voltage amplifier, Computer, High-precision CCD, Renishaw Raman spectrometer, Optical microscope, High-precision three-dimensional programmable stage, LM0202 electro-optic modulator, 514 nm argon ion laser source, Self-developed synchronous signal generator, etc.

Experimental Process:

Figure 1: Schematic diagram of the dynamic stress testing system for microstructures based on Raman spectroscopy

A testing system was constructed as shown in the figure above. In this system, an amplified sinusoidal signal drives the silicon micro-resonator, while a pulse signal of the same frequency is amplified to drive the electro-optic modulator, which modulates the laser beam. When a high voltage equal to the half-wave voltage of the electro-optic modulator is applied, the laser beam can pass through almost completely. However, when a low voltage is applied to the electro-optic modulator, almost no laser light passes through, with an extinction ratio of up to 1/100, which is sufficient for the experimental requirements. Therefore, the pulse signal is used to modulate the laser source via the electro-optic modulator, generating discontinuous laser light to irradiate the sample, thereby inducing Raman scattering. The Raman-scattered light is collected by the optical microscope system via a CCD, and the information is transmitted to a PC. The collected Raman spectra are processed by software to derive the corresponding dynamic stress information.

Figure 2: Error analysis diagram of the testing system

Due to the significant environmental influence on the Raman testing system, an error test was first performed using a standard silicon sample (the Raman shift of the standard Si sample is 520 cm⁻¹) before the formal testing (Test conditions: ambient temperature of 290 K, recording Raman spectra every 60 seconds, with each spectrum recorded for 15 seconds, for a total test duration of 10 minutes). Figure 2 shows the random error analysis of this testing method: within the test time range, the maximum uncertainty of the Raman shift is ±0.02 cm⁻¹. According to the formula, the stress testing error of this system is approximately ±10 MPa.

Experimental Results:

Figure 3: Relationship between Raman shift and modulation frequency

Figure 4: Relationship between Raman spectral energy intensity and modulation signal duty cycle

The response of the Raman shift and Raman spectral energy intensity to changes in modulation frequency was tested using standard silicon as the test object. The test results are shown in Figures 3 and 4. Analysis of the results indicates that the Raman shift is not affected by the modulation frequency, while the peak energy intensity of the Raman spectrum is proportional to the duty cycle of the modulation signal. This confirms that the testing system meets the requirements for dynamic stress testing.

Voltage Amplifier Recommendation: ATA-2048

Figure: ATA-2048 High-Voltage Amplifier Specifications

The experimental materials in this article have been compiled and released by Xi'an Aigtek Electronics. For more experimental solutions, please continue to follow the Aigtek official website. Aigtek is a high-tech enterprise in China specializing in the research, development, production, and sales of measurement instruments. The company has consistently focused on the R&D and manufacturing of test instrument products such as power amplifiers, voltage amplifiers, power amplifier modules, and high-precision current sources.