Chip-Scale OCT Engine Using dFT Spectrometer and OPA Scanner
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional OCT systems face limitations in imaging depth, sensitivity roll-off, and speed due to finite spectrometer resolution and the need for complex assembly, which restricts their performance and scalability.
Innovation Solution
A single-chip OCT system integrating a digital Fourier-Transform (dFT) spectrometer, a variable delay optical interferometer, and a high-speed optical phased array (OPA) beam scanner, manufactured using CMOS microfabrication technologies, to enhance signal-to-noise ratio, axial resolution, and imaging depth while eliminating the need for moving parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional spectrometer is used in SD-OCT system, then the system can achieve spectral domain imaging, but the finite spectrometer resolution limits the imaging depth and causes sensitivity roll-off
Solution Approach 1:
The patent replaces the conventional mechanical spectrometer with a digital Fourier transform (dFT) spectrometer that uses optical switching and digital signal processing. This substitution eliminates the physical limitations of mechanical spectrometers, enabling extended imaging depth without sensitivity roll-off while maintaining high spectral resolution through computational methods.
Solution Approach 2:
The patent changes the fundamental operating parameters of the spectrometer by using digital Fourier transformation instead of physical dispersion elements. This allows the system to achieve super-linear scaling of imaging depth with spectral resolution, fundamentally altering the relationship between these parameters that constrains conventional SD-OCT systems.
2Reliability
If a conventional SD-OCT system is assembled with multiple components, then the system can function, but the assembly complexity increases and scalability is restricted
Solution Approach 1:
The patent merges the spectrometer, interferometer, and detection systems into an integrated dFT-OCT platform. By combining these previously separate components into a unified system with common optical paths and shared electronics, the patent reduces assembly complexity while maintaining full system functionality and improving reliability through reduced inter-component interfaces.
Solution Approach 2:
The patent designs the dFT-OCT system with multi-functional capabilities that can operate in both spectral domain and time-domain OCT modes, as well as providing both imaging and spectroscopy functions. This universal design reduces the need for multiple specialized components, thereby simplifying assembly while expanding system capabilities and scalability.
3Length of stationary object
If the spectrometer resolution is increased to improve imaging depth, then the imaging depth extends, but the sensitivity roll-off increases due to reduced contrast transfer
Solution Approach 1:
The patent replaces the mechanical spectrometer that suffers from contrast transfer limitations with a digital Fourier transform approach. This substitution allows the system to achieve high imaging depth without the sensitivity roll-off that plagues conventional systems, as the digital processing can maintain signal fidelity regardless of the optical path length difference between reference and sample arms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution achieves superior performance with enhanced sensitivity and speed, overcoming sensitivity roll-off and complexity issues, enabling imaging depths and axial resolutions significantly better than comparable SD-OCT systems, with scalable and low-cost manufacturing.
Implementation Method 1
measures a spectrum of an interference pattern formed by the reference beam and the light scattered and/or reflected by the sample
Implementation Method 2
high-speed optical phased array (OPA) beam scanner
Data Source
AI summary
An optical coherence tomography (OCT) engine includes a digital Fourier-Transform (dFT) spectrometer, a tunable delay line, and a high-speed optical phased array (OPA) scanner integrated onto a single chip. The broadband dFT spectrometer offers superior signal-to-noise ratio (SNR) and fine axial resolution; the tunable delay line ensures large imaging depth by circumventing sensitivity roll-off; and the OPA can scan the beams at GHz rates without moving parts. Unlike conventional spectrometers, the dFT spectrometer employs an optical switch network to retrieve spectral information in an exponentially scaling fashion—its performance doubles with every new optical switch added to the network. Moreover, it also benefits from the Fellgett's advantage, which provide a significant SNR edge over conventional spectrometers. The tunable delay line balances the path length difference between the reference and sample arms, avoiding any need to sample high-frequency spectral fringes.