Blood Flow Measurement Apparatus Vignetting Optimization
Solution Overview
Problem
Current blood flow measurement apparatuses for the eye fundus face challenges in optimizing the shift position of incident light to avoid vignetting, which prolongs the time required for accurate measurement and imposes a burden on the subject.
Innovation Solution
A blood flow measurement apparatus comprising a blood flow measuring unit, a movement mechanism, and a controller that adjusts the optical system's position using a first and second movement control to optimize the shift position, allowing for real-time vignetting judgment and adjustment, thereby reducing the time to achieve the optimal shift position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the shift amount is gradually increased to avoid vignetting, then the incident light can be made incident more obliquely on the blood vessel, but the time required to attain the optimum shift position becomes very long
Solution Approach 1:
The patent applies preliminary action by performing a vignetting check before the actual blood flow measurement. The optical system is shifted by a predetermined amount in the preliminary phase to determine the maximum shift position where vignetting does not occur. This pre-determined shift position is then used for the actual measurement, eliminating the need for gradual adjustment during the measurement process and significantly reducing the time required.
Solution Approach 2:
The patent implements dynamics by using different shift strategies for different phases of the measurement process. In the preliminary phase, a predetermined shift is applied to quickly establish the optimal position. In the actual measurement phase, this predetermined shift is maintained to ensure both oblique incidence for good Doppler signals and avoidance of vignetting, achieving a dynamic optimization approach.
2Measurement precision
If the incident light is shifted from the optical axis to achieve oblique incidence, then the Doppler signal quality improves, but vignetting at the pupil occurs more frequently
Solution Approach 1:
The patent performs a preliminary vignetting check to determine the maximum shift position where vignetting does not occur before conducting the actual blood flow measurement. This preliminary action establishes safe shift boundaries that prevent vignetting during the measurement phase while still allowing sufficient oblique incidence for good Doppler signal quality.
Solution Approach 2:
The patent changes the shift parameter from a gradual adjustment approach to a predetermined shift approach. By calculating and applying a specific predetermined shift amount based on the vignetting check results, the system optimizes the balance between achieving oblique incidence for Doppler signals and preventing vignetting at the pupil.
3Measurement precision
If automatic optimization of shift position is performed by gradually increasing the shift amount, then the optimum position can be found, but the operation time becomes excessively long and imposes burden on the subject
Solution Approach 1:
The patent performs the shift position optimization in a preliminary phase before the actual measurement. By conducting the vignetting check and determining the optimal shift position in advance, the system eliminates time-consuming gradual adjustments during the measurement phase, significantly improving measurement efficiency while maintaining optimization quality.
Solution Approach 2:
The patent segments the measurement process into two distinct phases: a preliminary phase for optimization and vignetting check, and an actual measurement phase for blood flow data collection. This segmentation allows the time-consuming optimization to occur separately before measurement, improving overall productivity without sacrificing measurement precision.
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 solution enables faster and more efficient optimization of the shift position, reducing the burden on the subject and improving the accuracy of blood flow measurements by minimizing vignetting and ensuring optimal Doppler signal acquisition.
Implementation Method 1
an optical system for applying an optical coherence tomography (OCT) scan to a fundus of a subject's eye
Implementation Method 2
obtain blood flow information based on data acquired by the OCT scan... In order to obtain optimum Doppler signals for eye fundus blood flow measurement
Data Source
AI summary
A blood flow measuring unit of a blood flow measurement apparatus of an embodiment includes an optical system for applying an OCT scan to an eye fundus and obtains blood flow information based on data acquired by the OCT scan. A movement mechanism moves the optical system. A controller applies a first movement control to the movement mechanism to move the optical system in a first direction orthogonal to an optical axis of the optical system by a predetermined distance from the optical axis. A judging unit judges occurrence of vignetting based on a detection result of return light of light incident on the eye through the optical system after the first movement control. The controller applies a second movement control to the movement mechanism to further move the optical system based on a judgement result obtained by the judging unit.