Endoscope Multi-order Lambda Quarter Waveplate Depolarization
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Solution Overview
Problem
In endoscope systems, the depth of field narrows with increasing pixel density, and existing methods to widen the depth of field using polarization-based optical-path splitters are limited by polarization-dependent light splitting and require complex depolarization arrangements.
Innovation Solution
Incorporating a multi-order λ/4 wavelength plate made of birefringent material between the objective optical system and the optical-path splitter, which satisfies specific conditional expressions for thickness and birefringence, to achieve effective depolarization and equal intensity splitting of light, allowing for a wider depth of field without complex depolarization plates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of pixels of the image sensor is increased, then the image resolution is improved, but the depth of field becomes narrower
Solution Approach 1:
The image sensor is divided into multiple pixel regions (e.g., first pixel region and second pixel region) with different pixel pitches. The first pixel region has a smaller pixel pitch for high-resolution imaging, while the second pixel region has a larger pixel pitch for maintaining depth of field. This segmentation allows different regions to serve different functional purposes simultaneously.
Solution Approach 2:
Different regions of the image sensor are assigned different local qualities in terms of pixel pitch. The first pixel region uses a smaller pixel pitch to achieve high resolution for specific areas of interest, while the second pixel region uses a larger pixel pitch to maintain adequate depth of field for other areas, optimizing overall image quality.
2Reliability
If an optical-path splitter using polarization is used to widen the depth of field, then the depth of field is improved, but the system requires complex depolarization arrangements
Solution Approach 1:
The patent extracts the depolarization function from a separate component and integrates it into the wavelength plate itself. The wavelength plate is designed with specific optical properties that enable it to depolarize light while maintaining the depth of field effect, eliminating the need for additional depolarization plates or complex arrangements.
Solution Approach 2:
The wavelength plate is designed to perform multiple functions simultaneously: it acts as a depolarization element and also serves as part of the optical path splitting mechanism. This multi-functionality reduces the overall number of components needed in the system while maintaining the desired depth of field effect.
3Device complexity
If a conventional wavelength plate is used for depolarization, then polarization-dependent light splitting is reduced, but the device size increases
Solution Approach 1:
The patent merges the wavelength plate and depolarization plate into a single integrated component. This combined structure performs both wavelength selection and depolarization functions simultaneously, reducing the overall device size while maintaining effective depolarization to minimize polarization-dependent variations in light splitting.
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 configuration enables a compact endoscope design with improved depolarization effects, maintaining image brightness and reducing polarization-dependent variations, thereby enhancing the depth of field and image quality.
Implementation Method 1
a λ/4 wavelength plate made of a birefringent material is disposed in an optical path between the objective optical system and the optical-path splitter
Data Source
AI summary
An endoscope includes in order from an object side to an image side, an objective optical system, an optical-path splitter which splits light from the objective optical system into two, and an image sensor which picks up two split images.A multi-order λ/4 wavelength plate made of a birefringent material is disposed in an optical path between the objective optical system and the optical-path splitter, andthe multi-order λ/4 wavelength plate satisfies the following conditional expressions (1) and (2)′.10≤(d/d0)×0.25≤85 (1)0.08<|Δn|<0.24 (2)′where,d denotes a thickness of the multi-order λ/4 wavelength plate,d0 denotes a thickness of the multi-order λ/4 wavelength plate, which becomes zero-order for an e-line, andΔn denotes a birefringence for the e-line of the multi-order λ/4 wavelength plate.