Imaging Optical System with Positive Lenses for Temperature-Stable Wide-Angle Performance
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Solution Overview
Problem
Existing imaging optical systems for vehicles face challenges in achieving a wide-angle, high-resolution, and high-relative-illumination design that maintains image quality across varying temperatures, while also being compact, lightweight, and cost-effective.
Innovation Solution
The imaging optical system is designed with a specific configuration of lenses, including a front group and a rear group, where the lens closest to the stop in each group is a positive lens, and satisfies conditional expressions to control temperature coefficients and viewing angles, ensuring high resolution and relative illumination without focus shift due to temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the viewing angle is widened to monitor vehicle surroundings, then the coverage area is improved, but relative illumination declines at the peripheral part of the image
Solution Approach 1:
The patent applies parameter changes by optimizing the conditional expressions involving temperature coefficients of refractive indices (dn3/dn4) and viewing angles (θ1). By carefully controlling these parameters within specific ranges, the optical system achieves both wide viewing angle and high relative illumination at the image periphery, resolving the contradiction between coverage area and illumination intensity.
2Device complexity
If a fixed focal focus lens is used to simplify the optical system, then device complexity is reduced, but image quality declines when focus shifts due to temperature changes
Solution Approach 1:
The patent controls the temperature coefficients of refractive indices (dn3 and dn4) within specific conditional expression ranges to compensate for focus shift caused by temperature changes. This parameter control approach maintains image quality across temperature variations without requiring complex active focus adjustment mechanisms, thus resolving the contradiction between device complexity and manufacturing precision.
3Manufacturing precision
If the number of lenses is increased to achieve high resolution and wide angle, then image quality is improved, but the system becomes larger and more expensive
Solution Approach 1:
The patent achieves high image quality with a reduced number of lenses by optimizing the temperature coefficients of refractive indices and viewing angle parameters. This parametric optimization allows fewer lens elements to achieve the same performance that would otherwise require more components, resolving the contradiction between manufacturing precision and device complexity.
4Area of moving object
If conventional optical systems are used to achieve wide angle, then the viewing angle is improved, but the systems are not compact, lightweight, or cost-effective
Solution Approach 1:
The patent achieves wide viewing angle with reduced system weight and size by optimizing the temperature coefficients of refractive indices (dn3/dn4) and viewing angle (θ1) parameters. This parametric control enables a more compact lens configuration that maintains wide-angle performance while reducing the number and size of lens elements, thus resolving the contradiction between viewing angle and system weight.
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 results in a small-sized, high-resolution, wide-angle imaging optical system with high relative illumination, capable of maintaining image quality across temperature variations, suitable for vehicle-mounted imaging apparatuses.
Implementation Method 1
a lens arranged closest to the stop in the front group is a positive lens, a lens arranged closest to the stop in the rear group is also a positive lens, and a conditional expression (1) and a conditional expression (2) below are satisfied: 0.20≤|dn3/dn4|×(y/f)×sinθ1
Implementation Method 2
dn3: a temperature coefficient of a relative refractive index at a temperature 20° C.-40° C. to a d line of the positive lens arranged closest to the stop in the front group, dn4: a temperature coefficient of a relative refractive index at a temperature 20° C.-40° C. to a d line of the positive lens arranged closest to the stop in the rear group
Data Source
AI summary
An imaging optical system according to the present invention is the imaging optical system composed by arranging a front group, a stop, and a rear group in order from an object side, a lens arranged closest to the stop in the front group is a positive lens, a lens arranged closest to the stop in the rear group is also a positive lens, and specific conditional expressions are satisfied. In addition, an imaging apparatus according to the present invention includes the imaging optical system.