Galvanometer Optical Path Switching for OCT Eye Imaging
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Solution Overview
Problem
Existing ophthalmic optical coherence tomography systems struggle with quickly switching between anterior and posterior eye segments for accurate imaging, leading to inaccurate measurements of eye axial length due to low resolution and the inability to focus on different shapes of the cornea and fundus.
Innovation Solution
An ophthalmic optical coherence tomography system with a Y-direction scanning unit and rotatable-adjustable total-reflection mirrors allows for quick switching between anterior and posterior eye segment imaging by adjusting the optical path using a galvanometer and optical path adjustment units, enabling precise focusing and accurate measurement of eye axial length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a movable probe moved by a stepping motor is used to adjust the optical path, then imaging of the cornea and fundus can be realized, but it takes a certain time for the motor to move back and forth, making it incapable of quickly switching between anterior and posterior eye segments
Solution Approach 1:
The patent replaces the stepping motor-driven movable probe with a galvanometer-based optical path adjustment unit. The galvanometer uses electromagnetic fields to rapidly deflect mirrors, eliminating the mechanical inertia and slow response of motor-driven systems. This substitution enables quick switching between anterior and posterior eye segments imaging without the time delay associated with motor movement.
2Manufacturing precision
If a single probe is used for imaging, then the device structure is simplified, but it is unable to focus at both the cornea and fundus due to their different shapes
Solution Approach 1:
The patent employs dynamic optical path adjustment using a galvanometer-driven mirror system that can rapidly change the angle and position of the optical path. This dynamic adjustment allows a single probe to focus on different eye segments (cornea and fundus) by changing the optical direction, eliminating the need for multiple fixed probes while maintaining focusing precision at varying depths and angles.
Solution Approach 2:
The single probe is designed with multi-functionality through the optical path adjustment unit, enabling it to serve multiple purposes: imaging both anterior (cornea) and posterior (fundus) eye segments. The galvanometer system allows the same probe to adapt its focal point dynamically, making one probe perform the work of multiple specialized probes.
3Measurement precision
If the optical path is adjusted by a movable probe with stepping motor, then the system structure is simplified, but measurement accuracy is reduced due to the inability to quickly switch and refocus
Solution Approach 1:
The patent replaces the stepping motor mechanical system with a galvanometer-based electromagnetic deflection system. This substitution provides faster response times and more precise angular control, enabling accurate measurement of eye axial length by quickly switching between anterior and posterior segments without the mechanical limitations of motor-driven probes.
Solution Approach 2:
The patent changes the control parameter from positional movement (stepping motor displacement) to angular deflection (galvanometer mirror angle). This parameter change enables finer control over the optical path direction, allowing precise focusing on different eye segments and improving measurement accuracy through rapid angular adjustment rather than slow linear movement.
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 system achieves real-time, high-resolution imaging of both anterior and posterior eye segments, enhancing measurement accuracy and reducing errors in eye axial length determination.
Implementation Method 1
the Y-direction scanning unit reflects light received by the X-direction scanning unit into the anterior eye segment imaging module; when the Y-direction scanning unit is at a second rotation angle, the Y-direction scanning unit reflects the light received by the X-direction scanning unit into the posterior eye segment imaging module
Implementation Method 2
a total-reflection mirror, a rotatable-adjustable total-reflection mirror, a dichroic mirror, and a fundus lens, and wherein: when the Y-direction scanning unit is rotated at the first rotation angle, the Y-direction scanning unit reflects light transmitted from the X-direction scanning unit to the total-reflection mirror; the total-reflection mirror reflects the light to the rotatable-adjustable total-reflection mirror
Implementation Method 3
the rotatable-adjustable total-reflection mirror cooperates with the Y-direction scanning unit to reflect the light transmitted on the rotatable-adjustable total-reflection mirror to the dichroic mirror; the dichroic mirror reflects the light to the fundus lens; and the light is transmitted through the fundus lens into a human eye
Implementation Method 4
the fiber coupler receives light scattered back by the sample arm, and the received light interferes with the light reflected back by the reference arm; and the detection module is used for detecting the interfered light
Data Source
AI summary
It is provided a method for quick switching to realize anterior and posterior eye segments imaging, which can realize quick switch and real-time image for locations at different depths. On one hand, with an ability of quick switch, objects at different depths can be measured, and the detection scope of the OCT system can be enhanced; the switch system is able to work stably and change positions accurately without influencing the signal-to-noise ratio of the system. On the other hand, the light beam can be respectively focalized at different locations. Thus, high quality of anterior and posterior eye segments imaging can be achieved with a relatively high lateral resolution for human eyes having different ametropia. Furthermore, based on the anterior and posterior eye segments imaging, an ability of real-time eye axial length measurement can be added.