Observation Optical System Diffractive Surface Repositioning
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Solution Overview
Problem
Conventional observation optical systems fail to adequately correct chromatic aberration and curvature of field, and may display unnecessary patterns due to the location of diffractive surfaces near the display surface.
Innovation Solution
A compact observation optical system comprising a positive lens, a negative lens, and an optical element with at least three surfaces, where the light beam is reflected multiple times within the optical element, and the refractive indices and Abbe numbers of the lenses are optimized to satisfy specific conditional expressions, preventing excessive undercorrection of curvature of field and lateral chromatic aberration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a diffractive optical element is disposed between the display element and the eccentric optical element, then the optical system can be compact, but the diffractive grating pattern may be visually recognized because the diffractive surface is located near the display surface
Solution Approach 1:
The patent moves the diffractive surface from the conventional position near the display surface to a position after the eccentric optical element by introducing a reflective surface. This dimensional repositioning in the optical path allows the diffractive element to maintain its compactness function while avoiding the harmful visible pattern effect at the display surface location.
Solution Approach 2:
The reflective surface acts as an intermediary element that redirects the light path. By placing the diffractive surface after this reflective surface, the system can achieve compactness without the diffractive pattern being directly visible at the display surface, as the light path is altered by the intermediary reflective element.
2Volume of moving object
If a concave lens joined with an eccentric optical element is disposed between the display element and the eccentric optical element, then the optical system can be compact, but the curvature of field cannot be sufficiently corrected
Solution Approach 1:
The patent changes the optical parameters by introducing a reflective surface with specific curvature and positioning the diffractive surface at a optimized location after the eccentric optical element. This parameter modification allows the system to achieve both compactness and adequate curvature of field correction, overcoming the limitation of the conventional concave lens configuration.
Solution Approach 2:
The system combines multiple optical elements (eccentric optical element, diffractive optical element, reflective surface) to create a composite optical system. This composite structure enables the system to simultaneously achieve compactness and proper curvature of field correction, as each element contributes different optical functions that complement each other.
3Volume of moving object
If the diffractive surface is located near the display surface, then the optical system can be compact, but unnecessary patterns may be observed
Solution Approach 1:
The patent repositions the diffractive surface in the optical path dimension, placing it after the eccentric optical element rather than near the display surface. This dimensional change in the optical path allows the system to maintain compactness while preventing the diffractive pattern from being observed as an unnecessary pattern by the user.
Solution Approach 2:
The reflective surface serves as an intermediary that alters the light path between the diffractive surface and the user's eye. By positioning the diffractive surface after this intermediary reflective surface, the system achieves compactness while the intermediary element prevents the diffractive pattern from reaching the user's eye as an observable unnecessary pattern.
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 system effectively corrects chromatic aberration and curvature of field while preventing the observation of unnecessary patterns, ensuring a clear and corrected image display.
Implementation Method 1
a positive lens, a negative lens, and an optical element having at least three optical surfaces. The light beam from the display element is reflected a plurality of times inside the optical element via the positive lens and the negative lens
Implementation Method 2
The light beam from the display element is reflected a plurality of times inside the optical element via the positive lens and the negative lens
Data Source
AI summary
An optical system configured to guide a light beam from a display element includes a positive lens, a negative lens, and an optical element having at least three optical surfaces. The light beam from the display element is reflected a plurality of times inside the optical element via the positive lens and the negative lens, and then travels to an exit pupil. A predetermined condition is satisfied.