Probe alignment and design issues of microelectromechanical system based optical coherence tomography endoscopic...

Area of Science:

• Biomedical Optics
• Medical Imaging
• Microelectromechanical Systems (MEMS)

Background:

• Endoscopic optical coherence tomography (OCT) utilizes microelectromechanical system (MEMS) technology for imaging.
• Optimizing the performance of small OCT imaging probes is crucial for clinical applications.

Purpose of the Study:

• To investigate the impact of MEMS mirror curvature and optical alignment on OCT endoscopic probe performance.
• To provide design guidelines for assembly tolerances and optimization of OCT endoscopic probes.

Main Methods:

• Theoretical analysis using Gaussian beam propagation.
• Optical simulations to confirm theoretical models.
• Experimental verification using a time-domain OCT system.

Main Results:

• OCT imaging is highly sensitive to fiber end-to-GRIN lens distance (within 0.1 mm) for achieving a working distance >3.5 mm and lateral resolution ~25 μm.
• MEMS mirror surface radius of curvature >200 mm has a negligible effect on image quality.
• Maximum astigmatism ratio of 1.1 was observed with cylindrical plastic tubing at a working distance of ~2.5 mm.

Conclusions:

• Precise control of fiber-optic components is critical for high-resolution endoscopic OCT.
• MEMS mirror design has flexibility regarding curvature for OCT probe applications.
• Understanding optical aberrations like astigmatism is important for probe design and interpretation of OCT images.