Multi-Focal Delay Line for OCT Eye Measurement
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Solution Overview
Problem
Current OCT instruments face challenges in rapidly and cost-effectively measuring the entire eye while minimizing the impact of eye movement, due to limitations in collimation/focusing mechanisms such as slow linear motor translators, expensive voice coil actuators, and thermally unstable liquid lenses.
Innovation Solution
A system utilizing a multi-focal delay line with an optical switch and positive lens system, allowing for rapid adjustment of light interfaces to focus on different eye regions, coupled with a light detector to measure interference signals and determine distances between eye features, thereby enabling efficient and accurate OCT measurements within a short timeframe.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If linear motor translators are used to adjust collimation/focus, then measurement coverage is improved, but measurement speed deteriorates (fractions of a second)
Solution Approach 1:
The patent replaces mechanical translation devices (linear motors, voice coils) with an optical switching system. The optical switch rapidly redirects light between multiple fixed optical paths, each with different collimation/focusing characteristics, achieving focus adjustment without mechanical movement. This substitution enables measurement completion in milliseconds rather than seconds or fractions of seconds.
2Speed
If voice coil actuators are used to adjust collimation/focus, then measurement speed is improved (10 msec), but device cost worsens (expensive)
Solution Approach 1:
The patent employs an optical switch, which is a relatively inexpensive component compared to voice coil actuators or linear motors. The system uses fixed optical elements (lenses, mirrors) positioned at different locations, eliminating the need for expensive moving parts. This approach achieves rapid focus switching at a fraction of the cost of electromechanical actuators.
3Speed
If electro-optic lenses are used to adjust collimation/focus, then measurement speed is improved, but device cost worsens (expensive) and compatibility with wide optical bandwidth deteriorates
Solution Approach 1:
The patent uses fixed optical elements (lenses and mirrors) that are wavelength-agnostic, meaning they work across the entire optical bandwidth required for OCT imaging. Unlike electro-optic lenses that may have limited bandwidth compatibility, these passive optical components universally handle all wavelengths without requiring active control or expensive materials.
4Ease of manufacture
If liquid lenses are used to adjust collimation/focus, then device cost is improved (economical), but thermal stability worsens and measurement precision deteriorates (aberrations)
Solution Approach 1:
The patent divides the optical system into multiple discrete, fixed optical paths, each with its own collimation/focusing characteristics. Instead of using a single adjustable liquid lens that introduces thermal instability and aberrations, the system segments the focus adjustment function across multiple static optical elements. The optical switch selects between these pre-configured paths, eliminating thermal drift and aberration issues while remaining cost-effective.
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 rapid, cost-effective OCT measurements of the entire eye, reducing the impact of eye movement and improving measurement accuracy by selectively focusing on various eye regions using a multi-focal delay line and optical switch, allowing for precise determination of distances between eye features.
Implementation Method 1
OCT is based on low-coherence interferometry that typically employs near-infrared light
Implementation Method 2
a positive lens system, wherein the light interfaces are all separated and spaced apart from the positive lens system and located at different distances than each other from an effective focal plane of the positive lens
Implementation Method 3
a light detector configured to receive the reference light from the reference optical path, and to receive the return light from the first optical system, and in response thereto to detect at least one interference signal
Data Source
AI summary
An optical coherence tomography (OCT) system includes: a light source; a multi-focal delay line; and a light detector. The multi-focal delay line includes: a positive lens; and an optical switch configured to: receive a light from the light source; selectively direct the sample light to the positive lens via a selected one of a plurality of light interfaces each located a different distance from the focal plane of the positive lens; and direct the sample light to an object to be measured. The light detector is configured to receive return light returned from the object to be measured in response to the sample light, and to receive a reference light produced from the light from the light source, and in response thereto to detect at least one interference signal. An associated OCT method may be performed with the OCT system.