Quasi-needle-like focus synthesized by optical coherence tomography.

Area of Science:

• Optical Imaging
• Microscopy
• Biophotonics

Background:

• Optical imaging systems face a trade-off between lateral resolution and depth of focus (DOF).
• Achieving high resolution over an extended depth range is a significant challenge in microscopy and biophotonics.

Purpose of the Study:

• To overcome the inherent resolution-DOF compromise in optical imaging.
• To develop a method for extending the depth of focus without sacrificing lateral resolution.

Main Methods:

• Synthesizing an effective point spread function in the optical path length (OPL) domain.
• Utilizing optical coherence tomography (OCT) to create a quasi-needle-like focus.
• Employing optical path length coded beams for focus synthesis.

Main Results:

• Demonstrated a four-fold extension of the conventional DOF.
• Achieved and maintained a high lateral resolution of 2.5 μm.
• Maintained high resolution over an extended depth range of approximately 240 μm.
• Showcased potential for further DOF extension by increasing coded beams.

Conclusions:

• The proposed synthetic focus effectively resolves the lateral resolution-DOF trade-off.
• The quasi-needle-like focus synthesized via OCT offers a significant advancement in optical imaging capabilities.
• This technique holds promise for applications requiring extended depth imaging with high resolution.