Ophthalmological Laser Polarization Beam Splitter Stray Light Suppression
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Solution Overview
Problem
Ophthalmological laser systems face challenges in accurately detecting light backscattered from the eye lens due to low intensity and high stray light levels, leading to flawed detection results.
Innovation Solution
The use of a polarization beam splitter to decouple detection light with a different polarization direction than the emitted illumination light, combined with an optical phase retardation system to modify the illumination light's polarization, effectively suppresses stray light and enhances signal strength by selectively detecting light backscattered from the eye lens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional beam splitters are used to detect backscattered light from the eye lens, then the detection system can be implemented, but stray light from optical component reflections contaminates the detection signal, reducing measurement precision
Solution Approach 1:
The invention changes the polarization state parameter of the illumination light using a quarter-wave plate, transforming linearly polarized light into circularly polarized light. This parameter change allows the backscattered light to have a different polarization state than the reflected stray light, enabling effective separation through the polarizing beam splitter and improving detection precision.
Solution Approach 2:
The polarizing beam splitter acts as an intermediary element that separates light based on polarization direction. It transmits the circularly polarized backscattered light to the detector while reflecting the linearly polarized stray light away from the detection path, thus mediating between the illumination source and detector to eliminate harmful stray light.
2Measurement precision
If the intensity of illumination light is increased to improve backscattered light detection, then signal strength increases, but radiation exposure to the patient increases
Solution Approach 1:
By changing the polarization parameter of the illumination light through the quarter-wave plate, the system optimizes the detection of backscattered light signal. This allows for improved signal strength through enhanced detection efficiency rather than simply increasing illumination intensity, thereby reducing the need for high radiation exposure.
Solution Approach 2:
The invention replaces the mechanical approach of increasing light intensity with an optical field approach using polarization manipulation. Instead of brute-force increasing illumination power, the system uses polarization state transformation to enhance the detectability of backscattered light, substituting intensity-based detection with polarization-based detection.
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 more accurate detection of the eye lens's form, structure, and position, enabling precise determination and therapy with reduced errors from stray light and patient movement, and minimizes radiation exposure during refractive surgical procedures.
Implementation Method 1
the beam splitter is a polarization beam splitter, which decouples the detection light on the detector in such a way that it exhibits a polarization direction different from the emitted illumination light
Implementation Method 2
an optical phase retardation system in the illumination beam path between the focusing optics and the examination region is arranged in such a way that the passing illumination light obtains a polarization direction corresponding to the decoupled detection light
Implementation Method 3
a laser, the radiation of which is focusable three-dimensionally variable in an eye lens
Implementation Method 4
radiation, which reaches the beam splitter from the direction of the examination region, reaches a detector as detection light through a confocal aperture diaphragm
Data Source
AI summary
A polarization beam splitter selectively decouples detection light onto a detector such that it has a polarization direction that differs from the emitted illumination light. This enables the detection of the light scattered back in the eye lens at a high level of accuracy, since stray light from reflections at optical components of the light path is suppressed. In the generating of photo disruptions or other incisions, the ray exposure of the retina may be reduced in that the incisions being furthest away from the laser are induced first such that laminar gas inclusions with an existence duration time of at least 5 seconds result. In this manner the laser radiation propagated in the direction of the retina in further incisions are scattered and partially reflected such that the influence impinging upon the retina is reduced.