Optical Beam Controller Frequency Separation for OCT
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Solution Overview
Problem
When multiple optical beams are used to irradiate a measurement object in optical coherence tomography, interference between the beams complicates the acquisition of high-accuracy structural data, particularly in wide-range measurements, leading to reduced spatial resolution and increased measurement time.
Innovation Solution
An optical beam controller generates multiple wavelength-swept optical beams and sets an optical frequency difference between them to be greater than the band of the photodetector, preventing interference by ensuring that the beat frequencies from overlapping beams are beyond the detector's bandwidth, thus allowing accurate interference tomographic imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If multiple optical beams are used to irradiate different positions of a measurement object simultaneously, then measurement time is reduced, but optical interference between beams occurs which reduces measurement precision
Solution Approach 1:
The patent applies parameter changes by adjusting the optical frequency of each beam. Specifically, it sets the optical frequency difference between any two beams to be larger than the band of the photodetector, which prevents interference between beams while allowing simultaneous irradiation of multiple positions, thus reducing measurement time without sacrificing precision
Solution Approach 2:
The patent introduces an intermediary approach by using frequency shifting as a mediator between beams. By ensuring the frequency difference exceeds the photodetector band, the system creates a protective barrier that prevents harmful interference while maintaining the beneficial simultaneous measurement capability
2Measurement precision
If a single optical beam is scanned across different positions using a galvano mirror, then spatial resolution is maintained, but measurement time becomes long when measuring wide range
Solution Approach 1:
The patent applies segmentation by dividing the measurement task into parallel operations. Instead of scanning a single beam sequentially across different positions, it segments the illumination into multiple simultaneous beams targeting different positions, thereby reducing total measurement time while maintaining resolution through controlled frequency separation
Solution Approach 2:
The patent transitions from a single-beam sequential approach to a multi-beam parallel approach by adding the frequency dimension as a separating characteristic. This allows multiple beams to occupy the same spatial field without interfering, effectively multiplying measurement throughput without sacrificing resolution
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
This approach eliminates the influence of optical interference on photoelectric conversion output, enabling highly accurate measurements and significantly reducing measurement time by allowing multiple beams to be applied simultaneously without interfering with each other.
Implementation Method 1
interference between the beams complicates the acquisition of high-accuracy structural data
Implementation Method 2
eliminates the influence of optical interference on photoelectric conversion output
Implementation Method 3
a position of a light scattered point in an optical axis direction, i.e., a depth direction is specified by analyzing a result acquired by causing reference light to interfere with object light
Data Source
AI summary
An optical beam controller includes: an optical multiple-beam generator generating a plurality of wavelength-swept optical beams; and an optical frequency difference setter setting an optical frequency difference in any combination of the plurality of optical beams in such a way as to be larger than a band of a photodetector that receives an optical beam.