Catadioptric Camera Lens Narrow Angle Compact Height
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Solution Overview
Problem
Existing camera lenses with catadioptric optical systems face challenges in achieving a small height and narrow angle with good optical characteristics, as the ratios of refractive index to Abbe number and focal length in existing designs are insufficient, resulting in a field of view angle greater than 21.4°, which is not narrow enough.
Innovation Solution
A camera lens design comprising two lens assemblies and one lens group, with specific refractive and reflective surfaces, optimized by controlling the ratios of refractive index to Abbe number and focal length, ensuring conditions such as 0.035≤(nd1/v1)+(nd2/v2)≤0.085 and −0.40≤(nd1+nd2)/f3g≤−0.10, to achieve a narrow angle and small height with improved optical path and aberration correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the ratios of refractive index to Abbe number and focal length are increased, then the field of view angle becomes narrower, but the optical path length increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the refractive indices (nd1, nd2) and Abbe numbers (v1, v2) of the lens materials, along with the focal length f3g of the third lens group. The specific mathematical relationships (0.035≤(nd1/v1)+(nd2/v2)≤0.085 and −0.40≤(nd1+nd2)/f3g≤−0.10) enable optimization of the field of view angle while managing the optical path length through material parameter selection.
Solution Approach 2:
The patent divides the optical system into three distinct lens groups with different functional characteristics. The first two lens assemblies provide refractive and reflective powers, while the third lens group provides refractive power. This segmentation allows each group to be optimized independently for specific functions, enabling narrow-angle achievement without proportionally increasing the entire optical path length.
2Length of moving object
If the optical system is designed for small height, then the lens structure becomes more compact, but the angle of view becomes wider
Solution Approach 1:
The patent inverts the conventional approach by using reflective surfaces in the first two lens assemblies instead of traditional refractive-only design. This inversion enables compact folding of the optical path, achieving small height while maintaining control over the angle of view through the specific mathematical relationships of refractive indices and focal lengths.
Solution Approach 2:
The patent transitions from a simple linear optical path to a multi-dimensional configuration by incorporating both refractive and reflective surfaces. This allows the optical path to fold back on itself, achieving compact height in one dimension while maintaining the necessary optical path length and controlling the angle of view through the third lens group's focal length.
3Shape
If the lens configuration is optimized for narrow angle, then the field of view is reduced, but the optical aberrations increase
Solution Approach 1:
The patent applies local quality by assigning different optical characteristics to different parts of the system. The first two lens assemblies with reflective surfaces handle specific aberration correction locally, while the third lens group provides overall refractive power and additional aberration control. This localized optimization maintains good optical characteristics despite the narrow-angle design.
Solution Approach 2:
The patent uses composite optical design by combining refractive lens elements with reflective surfaces in a catadioptric configuration. This composite approach leverages the advantages of both refractive and reflective optics, enabling narrow-angle performance while maintaining good optical characteristics through the specific mathematical relationships of the combined system.
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 design provides a compact, narrow-angle lens with improved diffraction limit and telephoto advantages, suitable for portable cameras with high-pixel CCD or CMOS imaging elements, ensuring good optical characteristics and a small height.
Implementation Method 1
a first lens assembly having a reflective power and a refractive power, wherein an object side surface of the first lens assembly includes a first refractive surface in a peripheral region
Implementation Method 2
a second reflective surface in a central region thereof; an image side surface of the second lens assembly includes a first reflective surface
Data Source
AI summary
Provided is a camera lens of a catadioptric optical system, consisting of two lens assemblies and one lens group and having a small height, a narrow angle, and good optical characteristics. The camera lens includes: a first lens assembly including an object side surface having a first refractive surface and a second reflective surface in a peripheral region and a central region thereof, and an image side surface having a second refractive surface, a fifth refractive surface and a sixth refractive surface that are sequentially arranged from a peripheral region to a central region thereof; a second lens assembly including an object side surface having a third refractive surface and a fourth refractive surface that are sequentially arranged from a peripheral region to a central region thereof, and an image side surface having a first reflective surface; and a third lens group having a refractive power.