OCT Apparatus Interference Signal Level Control
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Solution Overview
Problem
Conventional OCT apparatuses face issues with interference signal saturation and reduced signal-to-noise ratio due to low laser light source intensity, particularly when measuring objects with high reflection intensity or metal components like stents, leading to inadequate detection and reduced invasion depth.
Innovation Solution
An OCT apparatus with a demultiplexing device, irradiation device, detection device, structure information generation device, and interference signal level control device that detects return beam information and adjusts the signal level of the interference signal within a predetermined range, using a reference beam light quantity adjustment device to maintain a balanced light quantity ratio between the reference and return beams, preventing saturation and maintaining a high signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the laser light source intensity is increased to improve signal detection, then the signal-to-noise ratio improves, but the interference signal saturates and measurement precision deteriorates
Solution Approach 1:
The patent implements dynamic control of the reference beam light quantity through a variable optical attenuator that adjusts the attenuation amount based on real-time detection of interference signal levels. This dynamic adjustment allows the system to adapt to different measurement conditions, preventing saturation while maintaining high signal-to-noise ratio across varying object reflectivity conditions.
Solution Approach 2:
The patent employs a feedback mechanism where the detected interference signal level is fed back to the control unit, which then adjusts the reference beam light quantity accordingly. This closed-loop control ensures that the interference signal remains within the optimal detection range, balancing signal strength and preventing saturation.
2Object-generated harmful factors
If the laser light source intensity is decreased to prevent signal saturation, then signal saturation is avoided, but the signal-to-noise ratio deteriorates and measurement precision reduces
Solution Approach 1:
The system dynamically adjusts the reference beam intensity rather than using a fixed low intensity, allowing the beam to be dimmed when necessary to prevent saturation while being brightened when the object requires higher signal strength, thus maintaining optimal measurement precision across different conditions.
Solution Approach 2:
The patent changes the light quantity parameter of the reference beam dynamically based on the detected interference signal level. The control unit modifies the light quantity parameter in real-time to maintain the interference signal within the optimal detection range, preventing both saturation and excessive noise.
3Measurement precision
If the reference beam light quantity is increased to improve interference signal level, then the signal-to-noise ratio improves, but the light quantity ratio between reference and return beams becomes unbalanced and measurement precision deteriorates
Solution Approach 1:
The control unit uses feedback from the interference signal detection to adjust the reference beam light quantity, maintaining a balanced light quantity ratio between the reference beam and return beam. This feedback mechanism ensures that signal strength is optimized while preserving the balance necessary for accurate measurements.
Solution Approach 2:
The system dynamically changes the light quantity parameter of the reference beam to maintain an optimal balance with the return beam light quantity. This parameter adjustment ensures that the light quantity ratio remains within the optimal range for accurate interference measurement while providing sufficient signal strength.
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 detection of interference signals at an appropriate level without saturation, ensuring a high signal-to-noise ratio and effective generation of optical structure information for the measured object.
Implementation Method 1
splits low coherent light emitted from a light source into a measuring beam and a reference beam
Implementation Method 2
multiplexes a reflected beam or a backscattered beam from an object to be measured obtained when the measuring beam is applied to the object to be measured with the reference beam
Data Source
AI summary
An OCT measurement apparatus includes a level detection section which detects the signal level of a piece of signal intensity information in interference information outputted from an interference beam detection section, a variable optical attenuator (VOA) which adjusts the light quantity of a return beam of a reference beam, and a light quantity control section which controls the VOA on the basis of the signal level of the piece of signal intensity information in the interference information detected by the level detection section. Accordingly, an interference signal at an appropriate level can be detected without saturation of the interference signal and reduction of an S/N ratio, and optical structure information of an object to be measured can be generated using the interference signal.