Circular-Ranging OCT with Chirped Combs for Absolute Depth
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Solution Overview
Problem
Subsampled OCT systems are unable to determine the absolute depth of samples, which is crucial for applications requiring precise location measurements.
Innovation Solution
Implementing a chirped frequency comb source with a dispersive Fabry-Perot etalon in the optical path to generate degenerate frequency combs, allowing for the recovery of absolute depth information while maintaining high compression and imaging efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a single frequency comb source is used for subsampled OCT, then high speed and long depth range imaging is achieved, but absolute depth determination is lost
Solution Approach 1:
The single frequency comb source is segmented into multiple frequency combs with different repetition rates. Each comb provides a specific depth range measurement, and by combining measurements from multiple combs, the system achieves both high imaging speed and absolute depth determination capability.
Solution Approach 2:
The system transitions from a single-frequency-comb approach to a multi-frequency-comb approach, adding the dimension of frequency comb variety. This allows the system to resolve absolute depth by comparing measurements across different comb repetition rates, effectively adding a new measurement dimension.
2Length of stationary object
If optical subsampling is used for compression, then long depth range and high speed are achieved, but absolute depth information is lost
Solution Approach 1:
The system uses feedback from multiple frequency comb measurements to resolve the absolute depth. By comparing the depth measurements from different combs, the system can determine the integer number of coherence lengths and thus recover the absolute depth information that would otherwise be lost in the subsampled OCT process.
3Productivity
If traditional subsampled OCT is used, then high compression and imaging efficiency are maintained, but depth ambiguity remains
Solution Approach 1:
The system merges measurements from multiple frequency combs with different repetition rates. By combining the depth information from each comb, the system maintains high imaging efficiency while resolving the depth ambiguity that plagues traditional subsampled OCT systems.
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 accurate measurement of absolute depth in optical coherence tomography, enhancing applications such as surgical guidance and topographic imaging with improved depth perception.
Implementation Method 1
generate interference fringes between the collected backscattered radiation and the radiation delivered to the reference arm
Implementation Method 2
a dispersive Fabry-Perot etalon filter in the optical path to generate degenerate frequency combs
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 a first portion of the radiation is delivered to, 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 configured to compute the optical path depth of the sample from the received interference fringes.