OCT System Polarization Delay Element Parasitic Reflections
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Optical coherence tomography (OCT) systems face interference signal disturbances due to parasitic reflections, which impair the quality of the OCT signal by mixing light reflections from the object with those from optical components in the beam path.
Innovation Solution
Incorporating a polarization-dependent delay element in the object beam path and adjusting the polarization state of the reference beam path to maximize the polarization overlap between the object-reflected light and the reference light, while minimizing the overlap with parasitic reflections, using polarization-neutral and polarization-maintaining beam splitters and light guides to isolate and reduce parasitic reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional OCT system is used, then the imaging process is simple, but the interference signal is disturbed by parasitic reflections from optical components
Solution Approach 1:
The patent changes the polarization state parameter of light by introducing a polarization-dependent delay element (retarder) in the reference beam path. This element introduces a phase delay between orthogonal polarization components, transforming the polarization state to create polarization discrimination between object-reflected light and parasitic reflections, thereby improving signal quality without major system redesign
Solution Approach 2:
The patent introduces a polarization-dependent delay element as an intermediary component in the reference beam path. This element mediates the polarization state of reference light, enabling it to interfere constructively with object-reflected light while minimizing interference from parasitic reflections, thus improving signal quality without fundamentally changing the OCT system architecture
2Measurement precision
If polarization-dependent delay element is added to distinguish object light from parasitic reflections, then signal quality improves, but device complexity increases
Solution Approach 1:
The patent modifies the polarization state parameter of light using a polarization-dependent delay element (retarder) positioned in the reference beam path. This element introduces a controlled phase delay between orthogonal polarization components, creating polarization discrimination that enables accurate distinction between object-reflected light and parasitic reflections, thereby improving measurement precision
Solution Approach 2:
The patent replaces potential mechanical or complex spatial filtering methods with a polarization-based approach. By using a polarization-dependent delay element to manipulate polarization states, the system achieves signal discrimination through optical property manipulation rather than mechanical separation, reducing overall device complexity while maintaining measurement precision
3Reliability
If the polarization state is adjusted to maximize object light contribution, then the influence of parasitic reflections is minimized, but the alignment and adjustment process becomes more complex
Solution Approach 1:
The patent changes the polarization state parameter of reference light using a polarization-dependent delay element, introducing a phase delay that creates polarization discrimination. This parameter change enables the system to maximize object light contribution while minimizing parasitic reflections through polarization filtering at the detector, improving interference signal quality
Solution Approach 2:
The patent implements polarization control with feedback mechanisms to automatically optimize the polarization state. By monitoring the interference signal quality and adjusting the polarization-dependent delay element accordingly, the system maximizes object light contribution while minimizing parasitic reflections, reducing manual alignment complexity
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 effectively distinguishes between light reflected from the object and parasitic reflections, enhancing the quality of the OCT signal by maximizing the contribution of the object-reflected light while minimizing the impact of parasitic reflections, thereby improving the accuracy and clarity of the imaging information.
Implementation Method 1
a polarization-dependent delay element arranged in the object beam path. In a polarization-dependent retardation element, light passing through is delayed differently depending on the polarization state
Implementation Method 2
The OCT light can have a pure polarization state with a degree of polarization of, for example, at least 80%, preferably at least 90%. In one embodiment, the OCT light is linearly polarized prior to entering the retarder or beam splitter
Implementation Method 3
The beam splitter with which the OCT light is divided into an object beam path and a reference beam path can be a polarization-neutral beam splitter. A beam splitter is called polarization-neutral if the splitter properties are independent of the polarization state of the incident light
Implementation Method 4
The light from the reference beam path is brought to interference at an interference beam splitter with light from the object beam path. The polarization overlap between the light scattered back from the measurement object and the light arriving from the reference beam path is greater than the polarization overlap between the light reflected by one or more optical elements in the object beam path
Implementation Method 5
In addition or as an alternative to this, a polarization filter can be arranged between the OCT light source and the delay element. An optical device through which light can only pass in a polarized state is generally referred to as a polarization filter
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The invention relates to an OCT system with an OCT light source (16) for emitting OCT light (15) into an object beam path (23) and a reference beam path (24). The system comprises a detector (25, 52, 53) for detecting an interference signal produced by the object beam path (23) and the reference beam path (24). A polarization-dependent delay element (30) is arranged in the object beam path (23). The invention also relates to a corresponding OCT method. The invention allows the effects of parasitic reflections to be reduced.