Compact 4-Lens Optical System for Wide-Angle Imaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing image pickup apparatuses face challenges in achieving a wide angle of view and stable focal length while maintaining a small size, particularly in applications like endoscopes and car-mounted cameras, due to issues with aberrations and temperature fluctuations.
Innovation Solution
An optical system comprising a plurality of lenses with specific refractive powers and an aperture stop, where conditional expressions are satisfied to correct aberrations and maintain a stable focal length, including a configuration with a negative meniscus lens, a biconvex positive lens, and a biconvex positive lens, ensuring a wide angle of view and appropriate back focus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a wide angle of view is achieved using an objective optical system with a small number of lenses, then the device size is reduced, but aberration correction becomes insufficient
Solution Approach 1:
The patent applies parameter changes by carefully selecting the refractive indices and Abbe numbers of lens materials to satisfy specific conditional expressions. The first lens uses material with 1.45<n1<1.60 and 20<νd1<50, while the second lens uses material with 1.50<n2<1.70 and 30<νd2<80. This material parameter optimization enables effective aberration correction in a compact 4-lens configuration, resolving the contradiction between small size and aberration correction quality.
2Weight of moving object
If resin material is used for lenses to reduce weight, then the device becomes lighter, but focal length stability under temperature changes deteriorates
Solution Approach 1:
The patent addresses thermal stability by selecting resin materials with appropriate thermal expansion coefficients and maintaining specific air spaces between lenses. The conditional expression 0.03<D1Ls<0.15 and the material parameter selections ensure that thermal expansion effects are compensated, maintaining focal length stability despite using lightweight resin materials for the lenses.
3Volume of moving object
If the number of lenses is reduced for small-sizing, then the device becomes more compact, but the complexity of achieving stable focal length increases
Solution Approach 1:
The patent simplifies the control of focal length stability by establishing specific parameter ranges for lens materials and air spaces. The conditional expressions define precise ranges for refractive indices (1.45<n1<1.60, 1.50<n2<1.70), Abbe numbers (20<νd1<50, 30<νd2<80), and air space distances (0.03<D1Ls<0.15), enabling stable focal length in a compact 4-lens configuration without requiring complex additional components.
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 high-resolution, wide-angle image pickup with favorable off-axis aberration correction and minimal focal length fluctuations, even in small-sized devices, suitable for applications like capsule endoscopes and car-mounted cameras.
Implementation Method 1
an optical system which includes a plurality of lenses and an aperture stop... a first lens having a negative refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power
Data Source
AI summary
An image pickup apparatus includes an optical system which includes a plurality of lenses and an aperture stop, and an image sensor which is disposed at an image position of the optical system, wherein the optical system includes in order from an object side, a first lens having a negative refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, and a fourth lens, and the following conditional expressions (1) and (3) are satisfied:αmax−αmin<4.0×10−5/° C. (1), and0.2<D1Ls/DsF<3.0 (3).