Optical aberrations and modulation transfer function of a thermal lens for use in imaging

Area of Science:

• Optics and Photonics
• Fluid Dynamics
• Materials Science

Background:

• Thermal lensing in liquids is a known phenomenon affecting optical systems.
• Quantifying optical aberrations using Zernike polynomials is a standard technique.
• Convective effects in thermo-optical liquids are complex and not fully understood.

Purpose of the Study:

• To report optical aberrations of a thermal lens in liquid using Zernike polynomial coefficients for the first time.
• To investigate the impact of liquid convection on thermal lens imaging properties.
• To analyze the time evolution of thermal lens optical properties and the influence of laser illumination direction.

Main Methods:

• Formation and characterization of a thermal lens in a liquid medium.
• Analysis of optical aberrations using Zernike polynomial coefficients.
• Systematic study of laser illumination direction and its effect on thermal lensing.

Main Results:

• Optical aberrations of the thermal lens were successfully expressed using Zernike polynomial coefficients.
• Liquid convection was found to significantly alter the thermal lens's imaging properties, even with vertical laser illumination.
• The direction of laser illumination critically influences the thermal lens's optical power, aberration type, and temporal changes.

Conclusions:

• The study provides the first quantitative description of thermal lens aberrations in liquids via Zernike coefficients.
• Convection and laser illumination direction are crucial parameters that must be controlled for predictable thermal lens behavior.
• This research offers insights for designing and optimizing optical systems involving thermal lensing in liquids.