OCT Fixation Lamp Alignment via Fundus Camera Feedback
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Solution Overview
Problem
Existing OCT systems face difficulties in accurately guiding a desired position on the fundus to the vicinity of the optical axis, especially with large intervals of fixation lamp turn-on positions, leading to challenges in capturing high-quality tomographic images.
Innovation Solution
A tomographic image capturing apparatus that controls both the fixation lamp turn-on position and the scanning position based on operator input, using a fixation lamp projection angle table to adjust the measuring light projection position on the retina, ensuring the specified position on the fundus is aligned with the optical axis for precise image capture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixation lamp is used to guide a desired position on the fundus to the vicinity of the optical axis, then the line of sight of the subject's eye can be fixed, but with large intervals of fixation lamp turn-on positions, it becomes difficult to guide the predetermined position on the fundus to the vicinity of the optical axis
Solution Approach 1:
The patent introduces a fundus camera as an intermediary device that captures fundus images to determine the actual position of the fundus. This intermediary step allows the system to identify the precise location of the desired fundus position and calculate the appropriate fixation lamp turn-on position and scanning position, thereby resolving the contradiction between ease of operation and measurement precision.
Solution Approach 2:
The system uses feedback from fundus images captured by the fundus camera to adjust and determine the optimal fixation lamp turn-on position and scanning position. By continuously monitoring the fundus position through imaging and using this information to guide the OCT scanning, the system achieves precise alignment despite using discrete fixation lamp positions.
2Device complexity
If the fixation lamp turn-on positions are set with large intervals, then the device complexity is reduced, but it becomes difficult to guide the predetermined position on the fundus to the vicinity of the optical axis
Solution Approach 1:
The fundus camera serves as an intermediary that bridges the gap between the limited fixation lamp positions and the desired fundus target position. By capturing fundus images and calculating the appropriate scanning position based on the actual fundus location, the system maintains reliable image capture without requiring complex fixation lamp control with small intervals.
3Productivity
If the measuring light projection position is not aligned with the desired position on the fundus, then the scanning process is simplified, but the image quality of the tomographic image deteriorates
Solution Approach 1:
The system performs preliminary action by capturing fundus images before OCT scanning and using these images to determine the optimal scanning position. This preliminary step ensures that the measuring light is projected onto the correct fundus position, guaranteeing high image quality while maintaining scanning efficiency through automated position calculation.
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 simplifies the process of setting fixation lamp and scanning positions, allowing for easier and more accurate acquisition of tomographic images by ensuring the measuring light projection position is aligned with the desired area on the retina, enhancing image quality and efficiency.
Implementation Method 1
a fixation lamp is turned on and a predetermined position on the fundus is guided to the vicinity of the optical axis
Implementation Method 2
adjusting the position of the measuring light for optical interference on the fundus
Data Source
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Figure 3A
AI summary
A tomographic image capturing apparatus includes a fixation lamp (311) configured to guide a line of sight of a subject's eye, and a control unit (140) configured to control a projection position of measuring light according to a predetermined position on a fundus of the subject's eye and a projection position of the fixation lamp.