Chongqing Smart Science & Technology Development Co. Ltd. focuses on the advancement of measurement and calibration technologies, specifically for calibrating accelerometers and gyroscopes. Of particular interest to me are emerging technologies based on microelectromechanical systems (MEMS), which are integrated into devices like smartphones and autonomous vehicles.

One of the key technologies we utilize for calibrating accelerometers is the acousto-optic deflector (AOD). AODs leverage the acousto-optic effect, where sound waves interact with light waves to achieve precise beam deflection. This principle allows for high-speed and accurate measurements, which is crucial in calibration processes.

The Calibration Process

In our calibration setup, an AOD serves as a crucial component in the primary calibration of laser Doppler vibrometers (LDVs). The LDV is an instrument used to measure the velocity of moving objects, operating similarly to how we perceive changes in sound pitch from a moving train. When laser light reflects off a moving object, it experiences a frequency shift due to the Doppler effect.

In our system, the AOD is integrated to control the frequency of the laser light used in the LDV. By using a sinusoidal voltage generator, we can shift the frequency of the light by a known amount, enabling precise velocity measurements.

Key Characteristics of Acousto-optic Deflectors

Broad Diffraction Bandwidth: AODs can efficiently diffract light over a wide range of frequencies, making them versatile for multiple laser wavelengths.

Linear Relationship Between Deflection Angle and Driving Frequency: The deflection angle of the laser beam is directly proportional to the frequency of the driving ultrasonic wave, simplifying calibration and control.

Continuous Scanning Capability: AODs allow for continuous scanning of laser beams within a defined angle range, which is essential for high-speed applications.

Application Example: Laser Doppler Vibrometer Calibration

In our calibration system, we utilize two AODs. The first AOD shifts the laser light down by 110 MHz, while the second AOD shifts it back up by the same amount, with an additional smaller frequency shift. This configuration cancels out the large frequency shifts, allowing us to focus on the desired shift that simulates a velocity change.

The resulting frequency shift creates what we call a synthetic velocity shift, which can be calculated using the Doppler equation. Our calibration system not only enables the calibration of the LDV as a function of frequency but also allows us to characterize the bandwidth of the LDV effectively.

This innovative approach provides a more direct method of calibration that is traceable to the unit of time, enhancing the overall reliability and accuracy of our measurement systems.

In conclusion, the integration of acousto-optic deflectors into our calibration processes marks a significant advancement in measurement technologies. As we continue to refine and develop this system, we aim to make it more portable for field applications, thus enhancing its utility in various practical scenarios.

For more detailed insights into the principles and applications of acousto-optic deflectors, visit SMART SCI&TECH. Thank you for your attention!