Circular-Ranging OCT Absolute Depth Recovery Using Frequency Combs
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Solution Overview
Problem
Subsampled OCT systems are unable to determine absolute depth, which is crucial for certain applications requiring precise location measurements.
Innovation Solution
Implementing a degenerate frequency comb source with a chirped frequency comb or a combination of stepped and swept laser sources to measure absolute depth in circular-ranging optical coherence tomography (CR-OCT) systems, allowing for precise depth determination while maintaining high-speed and long-range imaging capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a single frequency comb source is used for subsampled OCT, then high speed and long range imaging are achieved, but absolute depth determination is lost
Solution Approach 1:
The imaging process is segmented into multiple passes or measurements, where the first pass captures high-speed long-range data using subsampled OCT, and subsequent passes or additional measurements capture reference data at known depths. This segmentation allows the system to maintain high imaging speed while periodically calibrating absolute depth using the reference measurements.
Solution Approach 2:
A reference sample with known depth characteristics is introduced as an intermediary element. This reference sample serves as a mediator between the subsampled OCT system and absolute depth determination, allowing the system to correlate subsampled measurements with known reference depths to recover absolute depth information without compromising imaging speed.
2Length of stationary object
If traditional subsampled OCT is used, then long range imaging is achieved, but absolute depth information is lost
Solution Approach 1:
Reference measurements are taken in advance or concurrently with the main imaging process. By performing preliminary measurements on a reference sample with known depth characteristics, the system establishes a reference framework that enables subsequent recovery of absolute depth information from the long-range subsampled OCT data without compromising the extended imaging range.
Solution Approach 2:
The system implements a feedback mechanism where reference measurements with known depths are continuously or periodically acquired and used to calibrate and correct the absolute depth information in the main imaging data. This feedback loop allows the system to maintain long imaging range while recovering lost absolute depth information through continuous reference-based correction.
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
Enables the recovery of absolute depth information in CR-OCT systems, enhancing applications such as surgical guidance and topographic imaging by providing accurate depth perception and location measurements.
Implementation Method 1
a second optical subsystem coupled to the reference arm and the first optical subsystem to generate interference fringes between the collected backscattered radiation and the radiation delivered to the reference arm
Data Source
Figure 1A~1B
Figure 2A
Figure 2B~2E
AI summary
An apparatus, including: an electromagnetic radiation source producing radiation for illuminating a sample located at an optical path depth, the electromagnetic radiation source providing the radiation to the sample to facilitate determining the optical path depth within the sample; an interferometer including: a reference arm to which a first portion of the radiation is delivered, a sample arm to which a second portion of the radiation is delivered, a first optical subsystem coupled to the sample arm to interrogate the sample with the radiation delivered to the sample arm and to collect backscattered radiation from the sample, and a second optical subsystem coupled to the reference arm and the first optical subsystem to generate interference fringes between the collected backscattered radiation and the radiation delivered to the reference arm; and a data collection and processing system in communication with the interferometer configured to compute the optical path depth of the sample from the received interference fringes.