Abstract
In Fourier-domain optical coherence tomography (OCT), the finite bandwidth of the acquisition electronics constrains the depth range and speed of the system. Circular-ranging (CR) OCT methods use optical-domain compression to surpass this limit. However, the CR-OCT system architectures of prior reports were limited by poor stability and were confined to the 1.55 µm wavelength range. In this work, we describe a novel CR-OCT architecture that is free from these limitations. To ensure stable operation, temperature sensitive optical modules within the system were replaced; the kilometer-length fiber spools used in the stretched-pulse mode-locked (SPML) laser was eliminated in favor of a single 10 meter, continuously chirped fiber Bragg grating, and the interferometer's passive optical quadrature demodulation circuit was replaced by an active technique using a lithium niobate phase modulator. For improved imaging penetration in biological tissues, the system operating wavelength was shifted to a center wavelength of 1.29 µm by leveraging the wavelength flexibility intrinsic to CFBG-based dispersive fibers. These improvements were achieved while maintaining a broad (100 nm) optical bandwidth, a long 4 cm imaging range, and a high 7.6 MHz A-line rate. By enhancing stability, simplifying overall system design, and operating at 1.3 µm, this CR-OCT architecture will allow a broader exploration of CR-OCT in both medical and non-medical applications.
Highlights
The imaging performance of an optical coherence tomography (OCT) system is primarily associated with the specifications of its optical subsystem, and depends critically on the electronic subsystem that serves to detect, digitize, transfer, and process the output optical signals
We present in this work an improved CR-OCT system architecture that addresses the instability of the prior design
We demonstrate for the first time CR-OCT imaging based on a CFBG-stretched-pulse mode-locked (SPML) laser
Summary
The imaging performance of an optical coherence tomography (OCT) system is primarily associated with the specifications of its optical subsystem (e.g., wavelength-swept laser), and depends critically on the electronic subsystem that serves to detect, digitize, transfer, and process the output optical signals The bandwidth of this system, for example, defines the rate at which signal information can be captured. The first high-speed CR-OCT system was described in [4], which presents the theory and operating principles In this prior report of CR-OCT [4], the system architecture combined several innovations: a stretched-pulse frequency comb source, a passive optical quadrature demodulation circuit, and CR-specific signal processing/image processing methods. This work describes the most compact and stable high speed CR-OCT system and can serve to accelerate the exploration of the architecture in a broad range of imaging applications
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call