Optical Fiber Tip Phase Correction for Lissajous Scanning Distortion
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Solution Overview
Problem
Optical scanning observation apparatuses using spiral scans face distortion and reduced resolution due to phase lag between the driving electrical signal and the fiber tip's vibration waveform, especially when operating near resonance frequencies, leading to image misalignment and reduced image quality.
Innovation Solution
An optical scanning observation apparatus that employs a Lissajous scan pattern by vibrating the fiber tip at orthogonal frequencies, with a phase adjustor correcting the phase shift between the drive waveform and the vibration waveform to minimize distortion and maintain resolution, using a phase adjuster to synchronize the driving electrical signals with the fiber tip's motion, and optionally utilizing a measurement unit to determine the resonance frequency and Q value for precise adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If spiral scan is used to scan the object of observation, then the image can be acquired, but phase lag between driving electrical signal and fiber tip vibration waveform causes image distortion and resolution loss
Solution Approach 1:
The patent transitions from a static spiral scan pattern to a dynamic Lissajous scan pattern that adapts to the fiber tip's actual vibration characteristics. By continuously adjusting the scan pattern based on measured phase lag and resonance frequency, the system maintains optimal image quality despite dynamic variations in fiber vibration behavior near resonance frequencies.
Solution Approach 2:
The patent implements a feedback mechanism where the actual vibration waveform of the fiber tip is measured and used to correct the driving electrical signal phase. The phase adjustor uses feedback from the measured phase lag to dynamically adjust the driving signal, ensuring synchronization between the drive waveform and actual fiber tip motion, thereby eliminating image distortion.
2Productivity
If operation near resonance frequency is performed to enhance scanning efficiency, then productivity increases, but phase shift between drive waveform and vibration waveform increases causing image misalignment
Solution Approach 1:
The patent performs preliminary measurement of the fiber tip's resonance frequency and Q value before conducting the actual scanning operation. This preliminary characterization allows the system to pre-calculate the appropriate driving frequency and phase adjustment parameters, enabling high-speed scanning near resonance while maintaining image alignment through pre-determined correction factors.
Solution Approach 2:
The patent dynamically changes operating parameters including driving frequency, phase offset, and scan pattern based on the measured resonance frequency and Q value. By adjusting these parameters in real-time according to the fiber's actual vibration characteristics, the system maintains both high scanning efficiency near resonance and accurate image alignment despite phase shifts.
3Manufacturing precision
If phase adjustment is performed to correct image distortion, then image quality improves, but additional control complexity is introduced
Solution Approach 1:
The patent implements a self-service mechanism where the system automatically measures its own fiber tip vibration characteristics and performs self-correction of phase lag without external intervention. The built-in measurement and phase adjustment functionality allows the system to autonomously maintain optimal image quality, reducing the need for complex external calibration equipment or manual adjustment procedures.
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 apparatus achieves clear and undistorted images without resolution loss, allowing for precise scanning and image generation with minimal phase shift corrections, even near resonance frequencies, by synchronizing the driving signals with the fiber tip's motion, thus maintaining image quality and resolution.
Implementation Method 1
a driver configured to drive the tip of the fiber in a Lissajous scan pattern by vibrating the tip of the fiber at a first frequency in a first direction and at a second frequency in a second direction
Implementation Method 2
a fiber configured to guide light from a light source
Implementation Method 3
a photodetector configured to detect light obtained from the object of observation by irradiation with the irradiation light and convert the light to an electrical signal
Data Source
AI summary
An optical scanning endoscope apparatus includes an optical fiber for illumination, a driver that drives the tip of the optical fiber for illumination in a Lissajous scan pattern, illumination lenses that irradiate an object of observation with irradiation light emitted from the tip of the fiber, a photodetector that detects light obtained from the object of observation by irradiation with the irradiation light and converts the light to an electrical signal, an image processor that generates an image based on the electrical signal output by the photodetector, and a phase adjustor that adjusts the phase of the drive waveform of the driver so as to correct a phase shift between the drive waveform of the tip of the fiber by the driver and the vibration waveform of the tip of the fiber.