Folded Prismatic Collimator for Multi-Source Light Alignment
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Solution Overview
Problem
Existing prismatic collimating devices face challenges in efficiently collimating light beams for displays, particularly in maintaining alignment and reducing complexity in design while accommodating multiple light sources and achieving desired optical properties.
Innovation Solution
A folded prismatic collimating device comprising two prisms with optically powered surfaces and an air gap, utilizing total internal reflection and refraction to collimate light beams, with features like reflective and anti-reflection coatings to enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single large prism is used for collimation, then the device can accommodate multiple light sources, but the alignment precision and manufacturing complexity increase significantly
Solution Approach 1:
The single large prism is divided into multiple smaller prisms (first prism and second prism) that can be separately manufactured and aligned. Each prism handles specific light sources, reducing the overall complexity and alignment difficulty while maintaining the capability to accommodate multiple light sources.
Solution Approach 2:
The prisms are arranged in a folded configuration where the output face of the first prism forms an angle (e.g., 45 degrees) with the input face of the second prism. This dimensional arrangement allows compact integration of multiple light paths while maintaining precise alignment through geometric relationships rather than relying solely on high-precision monolithic manufacturing.
2Volume of moving object
If a folded prism design is implemented, then the device size is reduced, but the optical path complexity and surface requirements increase
Solution Approach 1:
The patent applies freeform optical surfaces with specific curvatures to the prism faces. These curved surfaces are designed to collimate light from multiple point sources while accounting for the folded optical path. The curvature profiles are optimized to compensate for the increased optical path complexity introduced by the folded configuration, achieving compact size without sacrificing collimation quality.
3Reliability
If multiple prism surfaces are used for collimation, then the optical performance is improved, but the number of coatings and manufacturing steps increases
Solution Approach 1:
The patent combines multiple functional surfaces into integrated prism components. The freeform surfaces are designed to perform multiple optical functions (collimation, beam shaping, and path folding) simultaneously. This merging reduces the total number of separate optical elements and coatings required, simplifying manufacturing while maintaining high optical performance through optimized surface profiles.
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 device effectively collimates light beams, maintaining alignment and reducing design complexity, while accommodating multiple light sources, and achieving desired optical properties such as common or uncommon exit pupils and adjustable waist points.
Implementation Method 1
Light R interacts with a first surface 1301 of the first prism 1310 and enters the first prism 1310. The first surface 1301 of the first prism 1310 causes the light to undergo refraction towards a second surface 1302 of the first prism 1310.
Implementation Method 2
Due to the presence of the air gap 1330 and the angle of incidence of the light, the light that is refracted by the first surface 1301 undergoes total internal reflection (TIR) at the second surface 1302, and is reflected towards a third surface 1303.
Implementation Method 3
In some examples, to aid reflection the third surface 1303 and the fifth surface may be coated with a reflective mirror coating.
Data Source
Figure 1
Figure 2~3
AI summary
A prismatic collimating device (1300) to collimate image bearing light is disclosed. The prismatic collimating device comprises a first prism (1310) and a second prism (1320) arranged to receive and collimate a light beam (R). The first prism comprises an output surface (1302) adjacent to an input surface (1304) of the second prism. The first prism and second prism are arranged such that the light beam undergoes total internal reflection and refraction at both the output surface of the first prism and the input surface of the second prism. Each of the first prism and second prism comprising at least three optically powered surfaces.