Variable Power Optical System with Folded Light Path
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current image pickup optical systems fail to achieve sufficient miniaturization while maintaining high optical performance and low manufacturing errors, and they do not fully meet the demands of further reducing camera size as the trend of miniaturization progresses.
Innovation Solution
A variable power optical system is designed with a first lens group having negative refractive power, including a reflective optical element and a single negative lens, where the axial distance between this lens group and the image pickup surface changes, and the refractive index and Abbe number of the negative lens satisfy specific relationships to optimize image quality and size reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a conventional image pickup optical system is used, then the camera can achieve basic miniaturization, but further miniaturization is limited and the system cannot fully respond to the request of miniaturization
Solution Approach 1:
The patent introduces a reflective optical element that bends the light path by 90 degrees, changing the spatial arrangement from a linear configuration to a folded configuration. This dimensional change allows the optical system to achieve further miniaturization in the axial direction while maintaining the necessary optical path length and image quality.
Solution Approach 2:
The reflective optical element is integrated within the first lens group structure, with the negative lens positioned on the object side of the reflective element. This nested arrangement allows compact packaging of multiple optical components within a reduced overall volume, enabling further camera miniaturization.
2Length of moving object
If the axial distance between the first lens group and the image pickup surface is reduced for miniaturization, then camera size decreases, but manufacturing errors have greater influence on optical performance
Solution Approach 1:
The patent specifies precise parameter ranges for the negative lens, including refractive index Nd > 1.81 and Abbe number νd < 35.0, as well as specific focal length ratios (0.3 < f1/f < 0.6). These parameter constraints optimize the optical system's tolerance to manufacturing errors while maintaining compact dimensions.
Solution Approach 2:
The first lens group is designed with specific local characteristics: a negative lens with particular refractive properties positioned on the object side of the reflective element. This localized optimization of lens properties compensates for manufacturing errors in the compact configuration.
3Device complexity
If a single negative lens is used in the first lens group, then the structure is simplified and manufacturing is easier, but achieving high image quality becomes more difficult
Solution Approach 1:
The first lens group combines a negative lens with specific refractive index (Nd > 1.81) and Abbe number (νd < 35.0) materials with a reflective optical element. This composite structure achieves high image quality correction with minimal components, balancing simplicity and performance.
Solution Approach 2:
The patent replaces part of the refractive optical system with a reflective optical element that bends the light path. This substitution reduces the number of lens elements needed while maintaining or improving image quality, as the reflective element efficiently corrects optical aberrations.
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
The solution enables a compact, high-image-quality variable power optical system that meets the demands of miniaturization, reducing the size of the camera while maintaining excellent optical performance and minimizing manufacturing errors.
Implementation Method 1
a reflective optical element for bending a light path
Implementation Method 2
an only lens which is provided on a subject side of the reflective optical element and consists of a single negative lens
Data Source
AI summary
An object of the present invention is to provide a compact size variable power optical system capable of producing a high quality image. The variable power optical system comprises a plurality of lens groups for forming an optical image on an image surface of an image pickup device. Among the plurality of lens groups, the first lens group, which is disposed in the most subject side has a negative refraction power, includes at least a lens having a negative refraction power and a reflective optical element for bending the optical axis. When varying the variable power, the axial distance between the first lens group and the image surface varies. When Nd denotes the refraction power of the lens having negative refraction power at d-line, the refraction power satisfies the conditional formula Nd>1.81.