Beam Expanding Structure for Optical Display Modules
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Solution Overview
Problem
Existing optical display modules face challenges in expanding scanning light beams emitted from MEMS micro-mirrors to facilitate their combination with stacked waveguide structures, leading to difficulties in lightening and thinning the module.
Innovation Solution
A beam expanding structure comprising a stacked arrangement of transparent substrates with reflective and transflective areas, where the reflective areas reflect light to the transflective areas, enabling partial transmission and reflection to expand the light beam in one dimension, and subsequent expansion in a second dimension by a stacked array of waveguide structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a traditional eyepiece with large aperture is used to expand the light beam, then the exit pupil is ensured, but the volume of the optical display module increases significantly
Solution Approach 1:
The optical system is divided into multiple waveguide layers (first waveguide layer, second waveguide layer, third waveguide layer) that work together to expand the light beam. Each waveguide layer contributes to the overall beam expansion through its specific optical path design, replacing the need for a single large-volume eyepiece
Solution Approach 2:
The patent uses a stacked array of waveguide structures that utilize the vertical dimension (z-axis) to achieve beam expansion. By stacking multiple thin waveguide layers, the system expands the light beam in the horizontal dimension while maintaining a compact vertical profile, effectively trading vertical space for horizontal expansion capability
2Volume of moving object
If MEMS micro-mirror is used to generate scanning light beam, then the device is compact, but the light beam is relatively narrow and difficult to observe
Solution Approach 1:
The beam expanding structure is integrated within the optical display module, with the stacked waveguide array nested around the MEMS micro-mirror's optical path. The waveguide layers are positioned to receive and expand the narrow scanning beam from the MEMS device, creating a nested configuration where the expansion mechanism is contained within the overall module structure
Solution Approach 2:
The stacked array of waveguide structures utilizes the vertical dimension to achieve horizontal beam expansion. By stacking multiple thin waveguide layers in the vertical direction, the system transforms the narrow vertical beam from the MEMS micro-mirror into a wider horizontal beam, effectively using dimensional transformation to solve the beam width problem
3Weight of stationary object
If stacked array of waveguide structures is used to expand light beam, then the device can be lightened and thinned, but the scanning light beam from MEMS is too narrow to be effective
Solution Approach 1:
The waveguide structure is segmented into multiple thin layers, each contributing to the beam expansion function. This segmentation allows the system to achieve effective beam widening while keeping each individual layer thin and lightweight, collectively meeting both the weight reduction and beam expansion requirements
Solution Approach 2:
The optical display module combines different materials with complementary properties: the MEMS micro-mirror is made from lightweight materials to reduce weight, while the waveguide layers are constructed from optical materials that enable efficient light propagation and expansion. This composite approach allows the system to achieve both weight reduction and effective beam expansion
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 solution effectively expands the scanning light beam, enabling its combination with waveguide structures, resulting in a compact and lightweight optical display module.
Implementation Method 1
The first area of each transparent substrate is configured to reflect a light beam incident thereon to the second area of one or more transparent substrate at downstream
Implementation Method 2
the second area of each transparent substrate is configured to transmit part of a light beam received from one or more transparent substrate at upstream to an observation point
Implementation Method 3
reflecting rest of the light beam received from the one or more transparent substrate at upstream back to one or more transparent substrate at upstream
Implementation Method 4
the second area of each transparent substrate is further configured to at least partially reflect a light beam received from one or more transparent substrate at downstream back to one or more transparent substrate at downstream
Data Source
AI summary
A beam expanding structure and an optical display module are disclosed. The beam expanding structure includes a plurality of transparent substrates in a stacked arrangement. Each transparent substrate includes a first reflective area and a second transflective. In each transparent substrate, the first area is to reflect a light beam incident thereon to the second area of one or more transparent substrate at downstream; the second area is to transmit part of a light beam received from one or more transparent substrate at upstream to an observation point, while reflecting rest of the light beam received from the one or more transparent substrate at upstream back to one or more transparent substrate at upstream; and the second area is further to at least partially reflect a light beam received from one or more transparent substrate at downstream back to one or more transparent substrate at downstream.