Eyepiece Optical System Meniscus Member Ghost Image Reduction
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Solution Overview
Problem
Conventional eyepiece optical systems struggle to effectively suppress ghost images, particularly when the contrast of the real image is extremely strong, due to ambiguous application methods of antireflection coatings on protection windows.
Innovation Solution
An eyepiece optical system with a meniscus-shaped optical member on its periphery, where the radius of curvature (R) is such that 2.00 < |R|/fe < 22.00, where fe is the focal length of the eyepiece system, is used to reduce ghost images by providing a divergent effect to light rays, thereby separating the ghost image's focus away from the display member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If antireflection coating is applied on the protection window surface, then ghost images are reduced, but ghost images still appear when the contrast of the real image is extremely strong
Solution Approach 1:
The patent applies curvature to the protection window surface, specifically designing it with a meniscus shape where the radius of curvature R satisfies 2.00 < |R|/fe < 22.00. This curved surface configuration causes reflected light rays to diverge, preventing them from converging to form ghost images on the display member, thereby effectively eliminating ghost images even under extreme contrast conditions where antireflection coatings fail.
2Object-affected harmful factors
If a protection window member with curvature is used, then ghost images are prevented, but the application method is ambiguous making the effect difficult to obtain
Solution Approach 1:
The patent resolves the ambiguity by specifying precise parameter ranges for the curvature: the radius of curvature R must satisfy 2.00 < |R|/fe < 22.00, where fe is the focal length of the eyepiece system. Additionally, the meniscus shape is defined with specific constraints on the radii of curvature of the object-side and eye-side surfaces. These quantified parameters provide clear manufacturing guidelines, ensuring consistent ghost image prevention without ambiguity.
3Object-affected harmful factors
If the radius of curvature is increased to reduce ghost images, then ghost image visibility decreases, but optical performance and aberrations may be affected
Solution Approach 1:
The patent optimizes the balance between ghost image reduction and optical performance by defining a specific range for the radius of curvature parameter (2.00 < |R|/fe < 22.00). This parameter optimization ensures that the curvature is sufficient to diverge reflected light and prevent ghost images, while remaining within limits that maintain acceptable optical performance and minimize aberrations in the eyepiece 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
This configuration significantly reduces the visibility of ghost images while maintaining high optical performance and minimizing aberrations, with optimal results achieved when the radius of curvature is between 4.85 and 15.00, and the ghost image is positioned at least 3×(fe^2/1000) diopters away from the display member.
Implementation Method 1
light rays emanated from a luminous spot and the like in the field of view are reflected from an optical surface disposed to an eye side of the eyepiece system
Implementation Method 2
the optical member having meniscus shape at least on a periphery thereof... providing a divergent effect to light rays
Data Source
AI summary
Providing an eyepiece optical system 10 comprising: an eyepiece system 11; and an optical member 12 having a meniscus shape disposed to an eye side of the eyepiece system 11, the following conditional expression being satisfied:2.00<|R|/fe<22.00where fe denotes a focal length of the eyepiece system 11 when a diopter of the eyepiece system 11 is 0 (m−1), and R denotes a radius of curvature of the surface having the meniscus shape, and the optical member 12 with a meniscus shape having a concave surface facing the eye side.