Intraoperative OCT for surgical microscope with sensitivity drop and depth of focus correction based on variable
Optics Express
|February 9, 2019
Summary
This study introduces an improved surgical microscope-integrated optical coherence tomography (MI-OCT) system. The new active feedback method ensures uniform OCT image contrast across the surgical microscope's depth of focus (DOF), overcoming previous limitations.
Area of Science:
- Biomedical Optics
- Surgical Imaging Technology
Background:
- Conventional microscope-integrated optical coherence tomography (MI-OCT) systems suffer from sensitivity roll-off due to limited depth of focus (DOF).
- Electrically tunable lenses (ETLs) in existing MI-OCT systems can adjust focus but do not fully compensate for sensitivity loss from optical path length difference (OPD) mismatch.
Purpose of the Study:
- To develop an advanced MI-OCT system with an active feedback mechanism for uniform OCT image contrast throughout the surgical microscope's DOF.
- To overcome the sensitivity limitations of conventional MI-OCT systems, enabling high-quality imaging over extended sample depths.
Main Methods:
- Implemented an active feedback system combining an electrically tunable lens (ETL) for focal position adjustment and a linear motor for optical path length difference (OPD) matching.
- Designed an optical system to preserve OCT resolution and utilized a retroreflector for stable reference reflection intensity during OPD compensation.
- Simultaneously actuated the ETL and linear motor to maintain consistent sensitivity and OCT imaging performance.
Main Results:
- Achieved a sensitivity variation of only 3 dB over a 10-mm sample displacement, corresponding to the surgical microscope's DOF.
- Demonstrated uniform high sensitivity across the entire depth of focus, overcoming the limitations of shorter OCT DOF.
- Successfully acquired optimal sensitivity OCT images of a mouse brain tumor model.
Conclusions:
- The proposed active feedback MI-OCT system effectively maintains high sensitivity and optimal image contrast over the full DOF of a surgical microscope.
- This advancement enables high-performance OCT imaging in surgical applications without being constrained by short OCT DOF limitations.
- The system shows significant potential for enhanced visualization during surgical procedures.
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