VCSEL Swept-Source Interferometer Control for Whole-Eye Biometry
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Solution Overview
Problem
Existing SS-OCT systems face challenges in achieving high-resolution whole-eye scans due to limitations in wavelength tunability, coherence length, and repetition rate, particularly when using VCSEL laser diodes, which are unsuitable for biometric measurements on the human eye.
Innovation Solution
Optimizing semiconductor laser diodes, specifically VCSEL laser diodes, through periodic current modulation to achieve a wide wavelength range, high coherence length, and high repetition rate, with parameters such as center wavelength (600-1400 nm), sweep rate (100 Hz-100 kHz), sweep range (3-75 nm), and optical power (50-20 000 μW), while ensuring compliance with safety regulations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If VCSEL laser diodes are used for SS-OCT systems, then device complexity is reduced and ease of manufacture is improved, but wavelength tunability range and coherence length are insufficient for whole-eye scans
Solution Approach 1:
The patent applies parameter changes by systematically optimizing multiple laser diode parameters including wavelength (600-1400 nm), sweep rate (100 Hz-100 kHz), sweep range (3-75 nm), optical power (50-20 000 μW), and coherence length (≥20 mm) to enable VCSEL-based systems to perform whole-eye scans while maintaining manufacturing simplicity
2Productivity
If higher repetition rate is achieved for fast scanning, then productivity is improved, but coherence length decreases reducing measurement depth
Solution Approach 1:
The patent resolves this contradiction by establishing an optimized parameter range where sweep rate is maintained between 100 Hz-100 kHz and coherence length is kept at least 20 mm, achieving both high productivity for fast scanning and sufficient measurement depth for whole-eye biometry
3Measurement precision
If optical power is increased to improve signal detection, then measurement precision is improved, but safety regulations may be violated
Solution Approach 1:
The patent optimizes optical power within the range of 50-20 000 μW to achieve sufficient signal detection precision for biometric measurements while maintaining compliance with laser safety regulations for ophthalmological applications
4Adaptability or versatility
If wide wavelength range is achieved for deep tissue penetration, then adaptability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent achieves a wavelength range of 600-1400 nm with sweep range of 3-75 nm using optimized VCSEL laser diodes, providing deep tissue penetration capability for whole-eye scans while maintaining relatively simple system architecture through parameter optimization rather than complex multi-component designs
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
Enables high-resolution, whole-eye biometric measurements by enhancing signal/noise ratio and minimizing motion artifacts, suitable for ophthalmological diagnostics and surgical interventions.
Implementation Method 1
a highly coherent spectral laser line is tunable with a highest possible repetition rate and over a wide wavelength range
Implementation Method 2
An interferometer is a technical optical device that uses the interferences for precision measurements. All effects that change the effective path length of the waves and thus properties of the superposed wave are measured.
Implementation Method 3
OCT systems based on the so-called 'swept source' technique (SS-OCT) have been used in recent years. This involves tuning the frequency of the light source and thereby generating the depth signals.
Data Source
AI summary
A method of controlling a semiconductor-laser-diode-based SS-interferometer system (SS=swept source), for a wide range of application suitable for use in ophthalmology, for example for imaging and for determining biometric measurement values of the eye. In a method according to the invention, by application of periodic current modulation, the operation of single semiconductor laser diode is designed such that a highly coherent spectral laser line can be adjusted with a highest possible repetition rate over a wide wavelength range. The parameters: center wavelength, sweep rate, sweep range, optical power in the eye and coherence length are adjusted such that the method is suitable for imaging and biometric applications via whole-eye scans. A semiconductor-laser-diode-based SS-interferometer system is provided, for biometric measuring of the eye. Embodiments are based for example on optical, coherence tomographic scan images. Applications lie in ophthalmological diagnostics, treatment and the preparation of surgical procedures and follow-up thereof.