Phase Modulator Speckle Removal Full-Field Eye Imaging
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Solution Overview
Problem
Existing full-field eye imaging techniques face challenges in removing speckles efficiently, especially when image acquisition time is short and reflexive eye movements are insufficient to wash out the speckle pattern.
Innovation Solution
A phase modulator is inserted into the detector leg of the interferometer, mimicking eye movements by introducing small phase modulations to the signal component only, using a transmissive glass plate with a polished central section and a roughened outer section to achieve this.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the image acquisition time is extended to achieve speckle pattern washout through reflexive eye movements, then speckle removal is improved, but the productivity decreases due to longer measurement time
Solution Approach 1:
The patent replaces the mechanical approach of relying on natural eye movements with an optical phase modulation system. A phase modulator is inserted in the reference arm of the interferometer to actively introduce phase variations that mimic the speckle washout effect, eliminating the need for extended acquisition times or dependence on patient eye movements.
Solution Approach 2:
The phase modulator applies periodic phase modulation to the reference beam at frequencies that correlate with typical eye movement characteristics. This periodic phase variation creates the necessary temporal decorrelation of speckle patterns, achieving washout effect within normal acquisition timeframes.
2Productivity
If the image acquisition time is shortened to improve productivity, then the measurement speed increases, but the speckle pattern washout effect becomes insufficient
Solution Approach 1:
The phase modulator pre-applies the necessary phase variations to the reference beam before detection occurs. By anticipating the need for speckle decorrelation and actively introducing phase modulations in advance, the system achieves effective speckle removal within the shortened acquisition window without requiring extended measurement times.
3Ease of operation
If active phase modulation is introduced to replace reflexive eye movements, then control and repeatability are improved, but the device complexity increases
Solution Approach 1:
The phase modulator serves as an intermediary component inserted in the reference arm of the interferometer. This single optical element mediates between the laser source and the sample arm, introducing the necessary phase variations without requiring complex mechanical movement systems or multiple additional components.
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 allows for effective speckle removal in full-field eye imaging, enabling shorter acquisition times while maintaining image quality, and providing repeatability and control over the phase modification process.
Implementation Method 1
an outer section, which is in a form of a ring and has its surface roughened to the level of 2π
Implementation Method 2
the level of speckles in the interferogram combined on the detector from the signal and reference beams
Data Source
Figure 1~3
Figure 4
AI summary
Phase modulator suitable for speckle removal in full-field eye imaging, wherein the phase modulator is a transmissive glass plate having two sections. An interferometer for speckle removal in full-field eye imaging comprising: a detector, a light source arranged to produce two beams using a beamsplitter, the first a signal beam, directed to the measured object and the second reference beam, lenses, and an optical wherein the phase modulator is placed in the detector leg in the position in which the signal beam has a broader cross-section compared to the collinear reference beam, and wherein the phase modulator is arranged to allow rotation in the axis perpendicular to the light beam, the signal beam and the reference beam are arranged that the reference beam is focused and passes only through the polished central section of the phase modulator while the signal beam passes through the entire available aperture of the phase modulator, being subject to phase modulation caused by the roughened surface of the phase modulator, and wherein the signal beam and the reference beam are arranged that the signal beam and the reference beam are collinear but spatially separated due to different beam cross-sections to the extent that allows to perform phase manipulations to only one of them without disturbing another while maintaining the same common gross phase shift coming from the phase modulator thickness. A method of speckle removal in full-field eye imaging.