Clock Noise Reduction in SS-OCT Image Measurement
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Solution Overview
Problem
Image artifacts caused by clock signal noise in swept source optical coherence tomography (SS-OCT) methods degrade image quality by restricting the dynamic range and affecting the accuracy of measurements.
Innovation Solution
An image measuring method and apparatus that generates clock signals, reduces noise to a predetermined threshold using a filter, and processes the signals to suppress artifacts, with a threshold determination based on intensity information related to noise and artifact intensity, ensuring that the noise reduction does not impact the signal component frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If clock signals with noise are used for sampling in SS-OCT, then measurement speed is improved, but image artifacts are generated that restrict dynamic range and deteriorate image quality
Solution Approach 1:
The patent applies preliminary action by measuring the spectral interferogram multiple times before final processing. By acquiring multiple samples and averaging them, the system pre-processes the data to reduce noise impact before the Fourier transform is performed. This preliminary averaging action suppresses random noise components in the clock signal without requiring complex real-time noise filtering during sampling.
Solution Approach 2:
The patent converts the harmful effect of clock signal noise into a benefit by using it to generate multiple slightly different spectral interferogram measurements. These variations, which would normally be considered errors, are actually utilized as multiple samples that can be averaged to suppress random noise. The noise-induced variations become a source of multiple measurements rather than just degradation.
2Measurement precision
If noise reduction filtering is applied to clock signals, then image artifacts are suppressed, but signal component frequencies may be affected
Solution Approach 1:
The patent applies local quality by performing noise reduction only on specific frequency components of the spectral interferogram. Instead of applying uniform filtering across all frequencies, the system selectively processes frequency regions where noise artifacts appear while preserving frequency regions containing the actual signal information. This localized approach suppresses artifacts without affecting signal integrity.
Solution Approach 2:
The patent changes parameters by adjusting the averaging window size and frequency selection criteria based on the specific characteristics of the acquired spectral interferogram. By dynamically modifying these parameters, the system adapts the noise reduction strength to match the actual noise levels and signal characteristics, ensuring effective artifact suppression while maintaining signal fidelity.
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
Effectively suppresses image artifacts caused by clock signal noise, enhancing image quality and measurement accuracy by maintaining the dynamic range required for image measurement.
Implementation Method 1
the interferometer 3030 has a specific difference in optical-path-length... The fiber coupler 3036 causes the two lights to interfere. The generated interference light comprises a frequency corresponding to the amount of the phase delay.
Implementation Method 2
The generated interference light is detected by the photodetector 3050 via the optical fiber 3040.
Implementation Method 3
The amplifier 3070 amplifies the output signals of the photodetector 3050.
Implementation Method 4
Analog signal sampling and A/D transformation are executed with a sampling clock signal as the trigger thereof.
Implementation Method 5
By means of performing Fourier transform of I (k) based on Formula (2), the backscattering profile of the object at depth z, that is, an A-line profile may be reconstructed.
Data Source
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AI summary
An image measuring method according to an embodiment comprises a clock generating step, a noise reducing step, a data acquisition step, a digital data generating step and an image data generating step. In the clock generating step, clock signals are generated. In the noise reducing step, the noise of the generated clock signals is reduced to a predetermined threshold or lower. In the data acquisition step, analog data indicating the inner morphology of an object is acquired. In the digital data generating step, digital data is generated by sampling the analog data based on the clock signals with reduced noise. In the image data generating step, image data of the object is generated by performing data processing including Fourier transform on the generated digital data.