Laser Doppler Vibrometry for Eye Surface Vibration Measurement
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Solution Overview
Problem
Current methods for measuring eye surface vibration to determine cell damage during laser treatment are limited by the size of contact apparatuses used with piezoelectric sensors, which result in interference and reduced accuracy due to the large size relative to the wavelength of pressure waves, leading to modest signal strength above noise levels.
Innovation Solution
The use of laser Doppler vibrometry to measure eye surface vibrations by directing a probe laser beam towards the eye, splitting it into a reference and sample beam, detecting the interference between the two, and processing the beat pattern signal to determine cell damage based on frequency, providing improved spectral and spatial resolution and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If piezoelectric sensors mounted via contact lens apparatus are used to measure eye surface vibration, then measurement capability is achieved, but measurement precision deteriorates due to large apparatus size relative to pressure wave wavelength causing interference
Solution Approach 1:
The patent replaces the mechanical contact lens apparatus with piezoelectric sensors with an optical measurement system using laser Doppler vibrometry. The laser beam measures surface vibrations without physical contact, eliminating the interference caused by the large mechanical contact apparatus while maintaining measurement capability.
Solution Approach 2:
The patent introduces laser light as an intermediary medium to transfer measurement information from the eye surface to the detector without requiring direct mechanical contact. The laser beam interacts with the eye surface vibrations and carries this information through the vitreous humor to the detector, avoiding the interference problems of direct mechanical contact.
2Reliability
If contact lens apparatus with piezoelectric sensors is used, then vibration measurement is possible, but signal strength remains modest above noise level
Solution Approach 1:
The optical laser Doppler system replaces the mechanical piezoelectric sensing system, enabling detection of weaker vibration signals with higher signal-to-noise ratio. The optical method does not require strong mechanical coupling and can detect subtle surface vibrations that produce only modest signals in mechanical sensors.
Solution Approach 2:
The patent changes the measurement parameter from mechanical displacement (piezoelectric) to optical frequency modulation (Doppler shift). This parameter change enables detection of smaller amplitude vibrations with higher precision, improving the reliability of the measurement signal above the noise floor.
3Measurement precision
If large contact apparatus is used for measurement, then structural stability is maintained, but spectral and spatial resolution are reduced
Solution Approach 1:
The patent replaces the extended mechanical contact apparatus with a focused laser beam that can be confined to a small spot size on the eye surface. This optical approach achieves high spatial resolution because the laser spot can be much smaller than the physical dimensions of any contact lens apparatus, while maintaining structural stability through non-contact measurement.
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
Laser Doppler vibrometry offers enhanced sensitivity and accuracy in measuring eye surface vibrations, allowing for more precise determination of cell damage through improved signal quality and reduced interference, leading to better patient outcomes and simplified implementation for ophthalmologists.
Implementation Method 1
laser Doppler vibrometry to measure eye surface vibrations by directing a probe laser beam towards the eye, splitting it into a reference and sample beam, detecting the interference between the two
Implementation Method 2
detecting the interference between the two, and processing the beat pattern signal to determine cell damage based on frequency
Data Source
AI summary
Technologies are described for detection of eye surface vibrations to determine cell damage within a treatment area of an eye undergoing laser treatment. Eye surface vibrations may be caused by intraocular pressure waves that form during the laser treatment. For example, the pressure waves may originate from a plurality of bubbles forming and/or rupturing inside cells located in the treatment area. The bubbles may form as energy from a treatment laser beam is absorbed by the retinal tissue. The pressure waves may be measured at the surface of the eye through Doppler vibrometry to determine if the cells within the treatment area have been damaged. The damage to the cells may include cell lysis, a rupture of cell membranes, scarring, and/or photocoagulation, among other examples.