Quasi-telecentric optical design of a microscope-compatible OCT scanner

Area of Science:

• Biomedical Optics
• Optical Engineering
• Medical Imaging

Background:

• Optical coherence tomography (OCT) is a powerful non-invasive imaging technique.
• Achieving consistent image quality in OCT requires precise control over the optical system.
• Existing OCT scanner designs can suffer from variations in spot size and ellipticity across the scan range.

Purpose of the Study:

• To design and validate an optimized quasi-telecentric optical scanner for OCT.
• To establish design criteria for achieving uniform spot size in OCT scanners.
• To demonstrate the performance of the scanner with in-vivo and ex-vivo biological samples.

Main Methods:

• Utilized optical design software for simulation of a quasi-telecentric scanner.
• Incorporated optimized optics to achieve a uniform Gaussian spot size.
• Integrated a microscope for precise sample guidance and documentation during OCT imaging.
• Performed measurements using a beam analyzer to validate simulation results.

Main Results:

• Achieved a uniform, 15-microm (1/e(2) diameter) Gaussian spot size over a 4.4mm transverse scan range.
• Model simulations closely agreed with experimental measurements.
• Identified a design criterion (0.05) for quasi-telecentric scanners, limiting spot size and ellipticity variation to 4% over the scan range.
• Demonstrated high-quality OCT images of human skin, nail fold, and embryonic hearts.

Conclusions:

• Optimized quasi-telecentric optics are crucial for enhancing OCT image quality.
• The proposed design criterion provides a guideline for developing high-performance OCT scanners.
• The developed OCT scanner is suitable for imaging small biological samples with high precision.