Periscope Imaging Lens Assembly With Asymmetric Ghost-Ray Shielding
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Solution Overview
Problem
Conventional periscope-type imaging lens assemblies face challenges in suppressing the increase in F number and reducing costs while achieving miniaturization, particularly due to ghost rays and the need for light-shielding masks.
Innovation Solution
The imaging lens assembly incorporates an optical axis direction changing element, such as a prism, with an asymmetric light-shielding mask and a lens group, where the prism includes an incident surface, reflective surface, and emitting surface, and the light-shielding mask has an asymmetric aperture to minimize ghost rays and maintain optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a light-shielding mask is disposed on the prism to shield light other than central rays, then ghost rays are reduced, but the F number increases
Solution Approach 1:
The patent applies asymmetry by providing an asymmetric light-shielding mask where the first light-shielding portion (shielding oblique rays from the object side) has a different shape and position than the second light-shielding portion (shielding reflected rays). This asymmetric configuration selectively blocks harmful ghost rays while preserving sufficient light transmission to maintain the F number, resolving the contradiction between ghost ray reduction and F number control
Solution Approach 2:
The light-shielding mask implements local quality by applying light-shielding portions only in specific regions where ghost rays are generated, rather than uniformly shielding the entire prism. The first and second light-shielding portions are strategically positioned to block only the problematic oblique and reflected rays, while leaving other regions open for normal light transmission, thus reducing ghosts without significantly increasing the F number
2Volume of moving object
If the imaging lens assembly is miniaturized, then the device size is reduced, but the optical performance deteriorates
Solution Approach 1:
The patent extracts and eliminates the harmful ghost rays through the asymmetric light-shielding mask, removing a detrimental element from the optical system. By taking out the ghost rays that would otherwise degrade optical performance, the system can achieve miniaturization without sacrificing reliability, as the ghost ray interference is actively removed rather than tolerated
Solution Approach 2:
The patent changes the parameters of the light-shielding mask (asymmetric shape, specific position, dimensions of first and second light-shielding portions) to optimize the balance between miniaturization and optical performance. By carefully adjusting these parameters, the system achieves compact size while maintaining favorable optical characteristics through precise control of light transmission and ghost ray suppression
3Length of moving object
If conventional periscope-type imaging lens assemblies are used, then the focal length is secured within limited space, but the manufacturing cost increases
Solution Approach 1:
The asymmetric light-shielding mask serves multiple functions: it blocks oblique rays from the object side, blocks reflected rays from reaching the image sensor, and maintains the F number. By consolidating these multiple functions into a single asymmetric mask structure, the manufacturing process is simplified compared to using multiple separate shielding components, thereby reducing manufacturing costs while achieving the required focal length in limited space
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 effectively reduces ghost rays and suppresses the increase in F number, allowing for a compact design with improved optical characteristics and reduced manufacturing costs.
Implementation Method 1
an optical axis direction changing element that changes an optical axis direction, the optical axis direction changing element includes an incident surface disposed on a first optical axis having a first optical axis direction before being changed and an emitting surface disposed on a second optical axis having a second optical axis direction after being changed
Data Source
AI summary
An imaging lens assembly includes: an optical axis direction changing element that changes an optical axis direction, the optical axis direction changing element includes an incident surface disposed on a first optical axis having a first optical axis direction before being changed and an emitting surface disposed on a second optical axis having a second optical axis direction after being changed; and a lens group disposed on the second optical axis on an image side of the optical axis direction changing element and including at least one lens, the imaging lens assembly is configured such that: P_in_L<P_in_R, where P_in_L is a distance from the first optical axis to one end of the incident surface on an opposite side of the lens group, and P_in_R is a distance from the first optical axis to another end of the incident surface on the lens group side.