Observation Optics With Variable Wire-Grid Pitch for Bright Peripheral Viewing
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Solution Overview
Problem
Existing observation optical systems using wire grid polarizers face challenges in maximizing transmittance of polarized light due to varying incident angles, particularly at the periphery, leading to decreased light transmission.
Innovation Solution
The optical system employs a lens with a first half-transmissive reflective surface featuring a metal wire microstructure with varying pitch based on the height from the optical axis, optimizing the spatial distribution of incident angles to enhance transmittance across different angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a wire grid polarizer with uniform metal wire pitch is used, then the structure is simple and easy to manufacture, but the transmittance of polarized light decreases at the periphery where light rays enter at oblique angles
Solution Approach 1:
The patent applies local quality by varying the pitch of the metal wire microstructure according to the height from the optical axis. The pitch is smaller at the periphery (larger height) and larger at the center (smaller height), optimizing the incident angle characteristic of transmittance for light rays at different positions. This non-uniform pitch distribution ensures that each region of the wire grid polarizer is optimized for the specific incident angles of light rays passing through that region, thereby maintaining high transmittance across the entire field of view.
2Illumination intensity
If the arrangement angle of the wire grid polarizer is controlled to maximize transmittance, then the transmittance improves for a specific incident angle, but it is difficult to maximize transmittance for all light rays having spatially different incident angles
Solution Approach 1:
The patent applies parameter changes by modifying the pitch parameter of the metal wire microstructure as a function of position (height from optical axis). Instead of using a fixed pitch, the pitch varies continuously or in steps according to the incident angle requirements at different field positions. This parameter variation allows the wire grid polarizer to adapt to different incident angles across the optical field, maximizing transmittance for both on-axis and peripheral light rays simultaneously.
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 increases the effective polarization transmittance of the system, ensuring bright image observation regardless of the incident angle, even with larger display devices.
Implementation Method 1
The first half-transmissive reflective surface has a metal wire microstructure. The first half-transmissive reflective surface has a polarization dependency.
Implementation Method 2
the light from the display device transmits through the second half-transmissive reflective surface, is reflected on the first half-transmissive reflective surface, is reflected on the second half-transmissive reflective surface
Data Source
AI summary
An observation optical system is configured to guide light from a display device to an observation side. The observation optical system includes a lens having a first half-transmissive reflective surface, and a second half-transmissive reflective surface disposed closer to the display device than the first half-transmissive reflective surface. The light from the display device transmits through the second half-transmissive reflective surface, is reflected on the first half-transmissive reflective surface, is reflected on the second half-transmissive reflective surface, transmits through the first half-transmissive reflective surface, and is guided to the observation side. The first half-transmissive reflective surface has a metal wire microstructure and a polarization dependency. A pitch of the metal wire microstructure changes according to a height from an optical axis of the lens.