Optical lock-in particle tracking in optical tweezers

Area of Science:

• Biophysics
• Optical Physics
• Nanotechnology

Background:

• Optical tweezers are crucial for manipulating microscopic particles.
• Low-frequency noise and laser instability limit the precision of optical tweezer measurements.
• Accurate particle tracking is essential for studying biological processes and material properties.

Purpose of the Study:

• To introduce a novel lock-in particle tracking scheme for optical tweezers.
• To demonstrate noise suppression capabilities of the new technique.
• To show the compatibility and simplicity of the proposed method.

Main Methods:

• Implementing a lock-in particle tracking scheme using stroboscopic modulation of the illuminating optical field.
• Performing position measurements equivalent to continuous measurement methods.
• Quantifying noise suppression at low frequencies (< 1 kHz) and around 630 kHz.

Main Results:

• Achieved up to 20 dB of noise suppression.
• Effectively mitigated low-frequency electronic noise.
• Reduced noise from laser relaxation oscillations around 630 kHz.
• Demonstrated a simple setup compatible with existing optical trapping systems.

Conclusions:

• The stroboscopic lock-in particle tracking scheme offers significant noise reduction in optical tweezers.
• This technique enhances measurement precision, particularly in the presence of electronic and laser noise.
• The method's simplicity and compatibility make it broadly applicable in various scientific fields.