Elliptical Aperture Lens Cap for Projector Edge Intensity Control
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Solution Overview
Problem
Conventional optical projectors face challenges in controlling the intensity of projected light patterns, particularly at the edges, to meet laser safety standards without reducing overall output power, and existing solutions are costly or degrade performance.
Innovation Solution
A lens cap with an elliptically shaped aperture and chamfered periphery is mechanically engaged over the projector lens assembly, providing vignetting to reduce the intensity of outermost rays while maintaining central intensity, thus meeting laser safety standards without altering the projector's internal structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional optical projectors project light patterns with high output power, then the overall brightness and visibility are improved, but the intensity at the edges and corners exceeds laser safety standards
Solution Approach 1:
The lens cap introduces local quality variation through its aperture geometry - the elliptical aperture with chamfered edges allows central light rays to pass through while blocking peripheral rays. This creates different transmission properties for different regions of the light pattern, maintaining high power in the center while reducing edge intensity to meet safety standards
Solution Approach 2:
The lens cap acts as an intermediary element between the light source and the projected pattern. By positioning the aperture at a specific distance from the lens assembly and using the offset center axis, it mediates the light distribution without requiring modification to the projector's internal structure, effectively controlling edge intensity while preserving overall output power
2Object-affected harmful factors
If masking elements or filters are used inside the projector to reduce edge intensity, then laser safety standards are met, but the overall output power and brightness are reduced
Solution Approach 1:
Instead of using internal masking elements that directly block light paths, the lens cap solves the problem in a different dimension - by controlling the angular distribution of light through aperture geometry and position. The chamfered edges and offset aperture create a vignetting effect that reduces edge intensity without uniformly blocking light, thereby maintaining overall output power while meeting safety standards
3Object-affected harmful factors
If the projector internal structure is modified to control light distribution, then edge intensity is reduced, but device complexity and manufacturing cost increase
Solution Approach 1:
The solution separates the light control function from the projector's internal structure by using a standalone lens cap. The aperture geometry (elliptical shape with chamfered edges) and its positioning relative to the lens assembly create the desired light distribution pattern without requiring integration into the projector's complex internal optical path
Solution Approach 2:
The lens cap serves as an external intermediary device that achieves edge intensity control without modifying the projector's internal structure. By positioning the aperture at a specific distance and using an offset center axis, it mediates the light distribution in a way that is simple to manufacture and implement while effectively reducing edge intensity
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 solution effectively suppresses corner peak radiation, ensuring the projected light pattern meets safety standards while maintaining high output power and avoiding performance degradation in imaging systems.
Implementation Method 1
the chamfered periphery is adapted to provide vignetting on the structured light projected from the pattern projecting unit
Data Source
AI summary
Various embodiments described herein relates to a lens cap, adapted to be mechanically engaged over a lens assembly of an optical projector. The lens cap, as described herein, is adapted for vignetting a light pattern projected by the optical projector. The lens cap includes a front surface and a back surface, where on at least a portion of the front surface, an elliptically shaped aperture is defined. In this aspect, the elliptically shaped aperture is chamfered towards its peripheral ends, as the elliptically shaped aperture extends out from the back surface of the lens cap towards the front surface of lens cap. Also, the elliptically shaped aperture is defined on the lens cap such that, a center axis of the aperture is offset to a central axis of the lens cap, so as to match an offset at which the light pattern is projected by the optical projector.