Compact Polarized Illuminator Using Folded Optical Path
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Solution Overview
Problem
Existing optical projection systems are not designed for high efficiency or brightness in compact applications, such as wearable or pocket-sized devices, due to limitations in miniaturization and component design.
Innovation Solution
The development of compact projection systems and components, including polarized illuminators and polarizing beamsplitters, that utilize a folded optical path, converging illumination beams, and beamsplitters with opposed prisms of different sizes, along with reflective polarizers and retarder films, to achieve miniaturization and high brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional projection systems are used, then high brightness and efficiency can be achieved, but the physical size becomes too large for compact applications
Solution Approach 1:
The patent employs a folded optical path that transitions from a linear arrangement to a three-dimensional configuration. Light reflects off a mirror at an angle, creating a compact polygonal path that achieves high brightness through multiple passes while reducing the overall device footprint. This dimensional transformation allows conventional high-brightness optics to fit within compact form factors.
Solution Approach 2:
The patent integrates multiple optical functions within a nested structure where the light source, mirror, and detector are arranged in a compact polygonal configuration. The mirror is positioned within the housing structure, and the detector is integrated into the same compact volume, allowing high-brightness illumination to be achieved without proportionally increasing device size.
2Volume of moving object
If the optical path is folded to reduce size, then compactness is achieved, but the complexity of the optical system increases
Solution Approach 1:
The folded optical path uses simple planar mirrors arranged at specific angles to create a polygonal light path. This approach achieves compactness through three-dimensional folding while maintaining relatively simple optical elements (flat mirrors) rather than complex curved optics or multiple lens systems, thus limiting the increase in device complexity.
3Volume of moving object
If the projector lens is made small to fit compact devices, then miniaturization is achieved, but the quality and performance of the projected image deteriorates
Solution Approach 1:
The patent uses a folded optical path that directs light through a compact polygonal route, allowing a small projector lens to collect and focus light effectively. The angular arrangement of the fold path compensates for the reduced lens size by optimizing the light cone geometry, thereby maintaining image quality despite the miniaturized lens dimensions.
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
These designs enable the creation of compact projectors that produce spatially uniform illumination and patterned light beams, suitable for small-scale applications, with improved efficiency and brightness, allowing for the miniaturization of optical components while maintaining high performance.
Implementation Method 1
a reflective polarizer configured to reflect light of a first polarization state and transmit light of a second polarization state
Implementation Method 2
a retarder film disposed within the reflective cavity
Implementation Method 3
a reflector configured to reflect light back through the reflective polarizer
Data Source
AI summary
Projection systems and components thereof are described that are well suited to miniaturization. These systems and components may use one or more of the following features: a folded optical path, as in a reflective cavity or a beamsplitter; an illumination beam that is converging at the place where it impinges upon the spatial light modulator; a beamsplitter that uses opposed prisms of substantially different sizes; a beamsplitter whose obliquely disposed partial reflector defines a first rectangular reference space, and where at least a portion of the light source or at least a portion of the projector lens is disposed within such first rectangular reference space; a system in which a ratio of areas of the first rectangular reference space and a second rectangular reference space is within a specified range, where the second rectangular reference space is just large enough to encompass the optical components of the projector; a system in which the projector lens is small compared to the spatial light modulator.