Dynamic Pupil Division for Autofocus Adaptability
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Solution Overview
Problem
Conventional distance measuring devices using pupil division by polarization have a low degree of freedom, limiting their ability to adapt to varying F-numbers and lens performance requirements.
Innovation Solution
A distance measuring device with a polarizing element and an optical rotatory plate that divides light into multiple regions, allowing independent control of polarizing axes and enabling flexible pupil division settings, combined with imaging elements to detect focus states based on image deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed pupil shielding member is used for pupil division, then the structure is simple, but the degree of freedom in setting pupil division regions is low
Solution Approach 1:
The patent replaces the fixed pupil shielding member with a liquid crystal optical rotatory plate that can dynamically change its optical rotation angle and pupil division pattern through electrical control. This allows the system to adapt pupil division regions according to different F-numbers and lens configurations, resolving the contradiction between adaptability and structural simplicity.
Solution Approach 2:
The liquid crystal optical rotatory plate changes its optical rotation parameter in response to control signals, enabling flexible adjustment of pupil division regions. By varying the optical rotation angle, the system can divide the pupil into different regions (e.g., left/right, upper/lower) without physical reconfiguration, thus achieving high adaptability with minimal structural complexity.
2Adaptability or versatility
If pupil division is performed by polarization, then focus detection can be achieved, but the system cannot adapt to varying F-numbers and lens performance requirements
Solution Approach 1:
The liquid crystal optical rotatory plate dynamically adjusts its optical rotation angle based on the F-number and lens characteristics, allowing the pupil division pattern to be optimized for different measurement conditions. This dynamic adaptation maintains focus detection accuracy across varying optical parameters.
Solution Approach 2:
The system changes the optical rotation parameter of the liquid crystal plate to match different F-numbers and lens performance requirements. By adjusting this parameter, the pupil division regions can be optimized for each specific optical configuration, ensuring accurate focus detection while adapting to various lens specifications.
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
Enhances the degree of freedom in setting pupil division regions, enabling accurate distance measurement for subjects with various patterns and lens configurations.
Implementation Method 1
a polarizing element (13) disposed on a plane conjugate with a pupil of an objective lens (11)
Implementation Method 2
an optical rotatory plate (15) rotating a polarizing axis of light which has passed through the polarizing element
Implementation Method 3
a polarization separation element (17) separating light which has passed through the optical rotatory plate into a first light beam and a second light beam
Data Source
AI summary
A distance measuring device including a polarizing element disposed on a plane conjugate with a pupil of an objective lens, an optical rotatory plate rotating a polarizing axis of light which has passed through the polarizing element, a polarization separation element separating light which has passed through the optical rotatory plate into a first light beam and a second light beam, a first imaging element forming a first image by the first light beam, a second imaging element forming a second image by the second light beam, and a focus detector detecting a focus state based on relative deviation between the first image and the second image which correspond to a same region of a subject.