Angular domain optical imaging using a micromachined tunnel array and a Keplerian lens system

Area of Science:

• Biomedical Optics
• Photonics
• Microfabrication

Background:

• Highly scattering media impede light penetration, limiting imaging depth and resolution.
• Traditional imaging techniques struggle to isolate quasi-ballistic photons for clear visualization.
• Angular Domain Imaging (ADI) offers a method to select specific photon trajectories.

Purpose of the Study:

• To investigate improvements in Angular Domain Imaging (ADI) using novel micromachined micro-tunnels.
• To enhance spatial resolution and image definition in scattering media.
• To evaluate the performance of ADI with reduced channel spacing and a Keplerian lens system.

Main Methods:

• Utilized newly micromachined silicon micro-tunnels with reduced spacing.
• Incorporated a Keplerian lens system to mitigate diffracted light from internal reflections.
• Employed an 808 nm wavelength laser for illumination.
• Tested the system with a 0.3% Intralipid solution and 100 micrometer test structures.

Main Results:

• Observed significant improvements in spatial resolution, characterized by sharper edges and enhanced definition.
• Successfully resolved test structure objects down to 100 micrometers.
• Demonstrated effective removal of diffracted light using the Keplerian lens system.
• Validated the enhanced ADI technique in a 2 cm long cuvette.

Conclusions:

• The modified ADI technique with novel micro-tunnels and Keplerian optics significantly enhances spatial resolution.
• This improved ADI system is capable of imaging fine details within scattering biological tissues.
• The findings support ADI as a promising technique for high-resolution imaging in turbid media.