Objective Optical System with Asymmetric Path Splitting
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Solution Overview
Problem
Existing optical systems for endoscopes face challenges in forming optical images with minimal differences in brightness and tone across different optical paths, leading to uneven image composition and reduced color reproducibility.
Innovation Solution
An objective optical system with a lens group and an optical path splitting element, where the optical path splitting element forms two optical paths with different lengths and transmission/reflection totals, and an optical surface with specific reflectivity ratios at 550 nm and 650 nm is positioned on the first optical path to equalize spectral characteristics, ensuring consistent brightness and tone across images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If different color filters are used for imaging two optical paths, then color reproducibility is improved, but device complexity increases
Solution Approach 1:
The patent applies homogeneity by using the same color filter for both optical paths instead of different color filters. This simplifies the device structure while still achieving good color reproducibility through the optical path splitting element design that equalizes the optical characteristics between the two paths.
2Manufacturing precision
If optical path lengths are made equal, then two in-focus optical images are formed on the same plane, but the device structure becomes more complex
Solution Approach 1:
The patent applies asymmetry by deliberately making the optical path lengths different rather than equal. The optical path splitting element is designed with asymmetric characteristics where the first optical path has a different path length from the second optical path, yet both paths still form in-focus images on the same plane through careful optical design.
3Illumination intensity
If the sum total of transmissions and reflections in one optical path is made larger, then light intensity is improved, but brightness uniformity between paths deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the reflectivity characteristics of the optical path splitting element. The reflectivity at specific wavelengths (550 nm and 650 nm) is carefully controlled to satisfy conditional expressions, which balances the light intensity between the two optical paths despite having different numbers of transmissions and reflections.
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 the formation of optical images with minimal differences in brightness and tone, improving image composition and color reproducibility by correcting relative luminance and saturation across images.
Implementation Method 1
the light beam made incident on the splitting element is divided into a reflection light beam and a transmitted light beam by a first surface
Implementation Method 2
The transmitted light beam transmitted through the first surface is reflected by a second surface located on an optical path
Implementation Method 3
an optical surface satisfying following conditional expression (1) is disposed on the first optical path: 0.8≤MR650/MR550≤0.9 where MR550 is reflectivity at a wavelength of 550 nm, and MR650 is reflectivity at a wavelength of 650 nm
Data Source
AI summary
An objective optical system includes a lens group and an optical path splitting element. The optical path splitting element is disposed on an optical path of the lens group, the optical path splitting element includes an optical path splitting surface configured to form a first optical path and a second optical path, an optical path length in the first optical path is different from an optical path length in the second optical path, a sum total of the number of transmissions of light and the number of reflections of light in the second optical path is larger than a sum total of the number of transmissions of light and the number of reflections of light in the first optical path, and an optical surface satisfying following conditional expression (1) is disposed on the first optical path,0.8≤MR650/MR550≤0.9 (1).