Wide-aperture aspherical lens for high-resolution terahertz imaging

Area of Science:

• Optics and Photonics
• Terahertz (THz) Technology
• Imaging Systems

Background:

• High-resolution imaging is critical in various scientific and industrial fields.
• Traditional terahertz (THz) imaging systems face limitations in resolving fine details.
• Developing advanced optical components is essential for pushing the boundaries of THz imaging capabilities.

Purpose of the Study:

• To introduce a novel wide-aperture aspherical lens specifically designed for high-resolution terahertz (THz) imaging.
• To analyze the optical performance and imaging capabilities of the proposed lens design.
• To demonstrate the practical application of the lens in imaging sub-wavelength scale elements.

Main Methods:

• Numerical analysis using geometrical optics and electrodynamics for lens design.
• Fabrication of the aspherical lens from high-density polyethylene using computer-controlled machining.
• Characterization of the lens performance using a continuous-wave THz imaging setup with a backward-wave oscillator and Golay detector.
• Evaluation of image quality based on the concept of image contrast.

Main Results:

• The wide-aperture aspherical lens was successfully designed, fabricated, and characterized.
• Experimental results demonstrated the lens's ability to resolve two points spaced at 0.95λ with 15% image contrast.
• The lens was employed to image a printed electronic circuit board, revealing sub-wavelength-scale elements with high resolution.

Conclusions:

• The developed wide-aperture aspherical lens offers a significant advancement in terahertz (THz) imaging resolution.
• The lens design proves highly effective in visualizing intricate details and sub-wavelength structures.
• This technology holds promise for enhancing various applications requiring high-resolution THz imaging.