PLL Sample Clock Synchronization for OCT Noise and Jitter
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Optical coherence tomography (OCT) systems face challenges in synchronizing data collection with the changing optical frequency of tunable light sources, leading to noise, jitter, and other undesirable effects due to the limitations of conventional clock generators.
Innovation Solution
The use of phase-locked loops (PLLs) with wide-bandwidth voltage-controlled oscillators (VCOs) and noise compensating subsystems to generate a stable clock signal for OCT systems, enabling efficient synchronization and reducing noise and jitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional clock generators are used to synchronize data collection with the changing optical frequency of tunable light sources, then the system structure is simple, but noise and jitter increase leading to degraded image quality
Solution Approach 1:
A phase-locked loop (PLL) is introduced as an intermediary device between the tunable light source and the data collection system. The PLL receives the frequency modulation signal from the light source and generates a synchronized clock signal with reduced noise and jitter, acting as a mediator that transforms the harmful frequency variations into a clean timing signal for data acquisition.
Solution Approach 2:
The phase-locked loop implements a feedback mechanism where the output clock signal is continuously compared with the input frequency modulation signal. The phase detector detects phase differences and feeds back control signals to the voltage-controlled oscillator to maintain synchronization, thereby reducing noise and jitter in the clock signal while keeping the system structure manageable.
2Productivity
If the optical frequency of the tunable light source changes rapidly over time, then the data collection speed increases, but synchronization errors increase leading to image degradation
Solution Approach 1:
The phase-locked loop employs a voltage-controlled oscillator (VCO) that can dynamically adjust its frequency in response to control signals. This dynamic capability allows the clock signal to track rapid frequency changes of the tunable light source while maintaining synchronization accuracy, enabling high data collection speeds without sacrificing precision.
Solution Approach 2:
The PLL generates the clock signal in advance of the actual data collection process. By pre-synchronizing the clock with the light source frequency variations and maintaining this synchronization through continuous phase monitoring, the system prepares timing signals that accurately correspond to the optical frequency at the moment of data acquisition, preventing synchronization errors.
3Adaptability or versatility
If a wide bandwidth is used for the voltage-controlled oscillator to track frequency changes, then the tracking capability improves, but noise susceptibility increases
Solution Approach 1:
The phase-locked loop uses a loop filter that allows partial bandwidth for tracking frequency changes while filtering out high-frequency noise. The filter is designed to pass the necessary frequency modulation signals for accurate tracking while attenuating noise components, achieving a balance between tracking capability and noise rejection rather than using full bandwidth.
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 effectively reduces noise and jitter, improving the resolution and dynamic range of OCT systems by generating a sample clock that is synchronized with the optical frequency of the tunable light source, thereby enhancing data acquisition in OCT systems.
Implementation Method 1
performing a frequency multiplication of a signal to generate a suitable clock signal using a phase-locked loop
Implementation Method 2
wide-bandwidth voltage-controlled oscillator (VCOs) to generate a stable clock signal
Implementation Method 3
noise compensating subsystems to generate a stable clock signal for OCT systems, enabling efficient synchronization and reducing noise and jitter
Data Source
AI summary
In part, the invention relates to an optical coherence tomography system that includes one or more phased-locked loop circuits. In one embodiment, the phased-locked loop circuit includes a phase detector, a loop filter, and a voltage controlled oscillator wherein the phased-locked loop circuit is configured to generate a sample clock. The optical coherence tomography system can include an analog to digital converter having a sample clock input, an interferometric signal input, and a sample data output, the analog to digital converter configured to receive the sample clock and sample OCT data in response thereto. In one embodiment, the phased-locked loop circuit is configured to lock on a first signal in less than or equal to about 1 microseconds.