Negative-Positive Lens Pair for Temperature-Stable Imaging
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Solution Overview
Problem
Existing optical systems for imaging apparatuses face challenges in achieving high optical performance across varying environmental temperatures, particularly in controlling focal position variation and correcting various aberrations.
Innovation Solution
The optical system comprises a negative lens and a positive lens adjacent to each other, with specific constraints on their distance, curvature radii, refractive indices, Abbe numbers, and temperature coefficients, allowing for effective temperature compensation and aberration correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pair of positive lens and negative lens having large differences in refractive index and Abbe number is employed to control variation in focal position, then temperature compensation is improved, but the degree of freedom in selection of lens material is reduced and aberration correction becomes difficult
Solution Approach 1:
The patent changes the critical parameter from requiring large differences in refractive index and Abbe number to requiring a specific difference in temperature coefficients of refractive index (|dnA/dt-dnB/dt|≥4.2×10^-6/°C). This parameter change enables temperature compensation while allowing broader material selection freedom and better aberration correction capability.
2Stability of the object's composition
If lens materials with large differences in refractive index and Abbe number are selected for temperature compensation, then focal position stability is improved, but various aberrations cannot be corrected effectively
Solution Approach 1:
The patent shifts the material selection criterion from large differences in refractive index and Abbe number to a minimum difference in temperature coefficients of refractive index. This enables simultaneous achievement of focal position stability through temperature compensation and effective aberration correction by allowing more flexible material combinations.
3Reliability
If the distance between negative lens and positive lens is increased to reduce thermal interference, then temperature compensation is improved, but the compactness of the optical system is reduced
Solution Approach 1:
The patent changes the material selection parameter to difference in temperature coefficients of refractive index, which enables effective temperature compensation even when the distance between lenses is small (0.00≤DAB≤1.00mm). This maintains compact optical system design while achieving reliable temperature compensation.
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 enables the optical system to maintain image forming performance across a wide range of temperatures, enhancing the degree of freedom in selecting lens materials and achieving both temperature compensation and aberration correction.
Implementation Method 1
dnA/dt [10−6/° C.] and dnB/dt [10−6/° C.] denote temperature coefficients of refractive indices of the negative lens and the positive lens, respectively, with respect to the d-line at 20° C. to 40° C., and either dnA/dt or dnB/dt has a negative sign
Implementation Method 2
RA and RB denote curvature radii of facing lens surfaces of the negative lens and the positive lens, respectively
Data Source
AI summary
An optical system includes a negative lens and a positive lens adjacent to each other, wherein the following inequalities are satisfied: 0.00≤DAB≤1.00, and 0.80≤RA/RB≤1.20, where DAB[mm] denotes a distance on an optical axis between the negative lens and the positive lens, and RA and RB denote curvature radii of facing lens surfaces of the negative lens and the positive lens, respectively, and wherein specific inequalities are satisfied.