Tilted Polarizing Beam Splitter for Projector Optical Path Reduction
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Solution Overview
Problem
Traditional MacNeille polarizing beam splitters used in projector optical systems have a long optical path, leading to decreased transmittance, especially in the blue wavelength band, and heat generation issues due to increased thickness.
Innovation Solution
A polarizing beam splitter design featuring a transparent optical member with at least one first polarizing beam splitting film tilted at a specific angle and a second film tilted in the opposite direction, reducing thickness and optical path length while maintaining efficient polarizing beam splitting capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the MacNeille PBS is increased in thickness to be suitable for entering light of a large aperture, then the aperture compatibility is improved, but the optical path becomes long and transmittance decreases due to absorption
Solution Approach 1:
The patent divides the single thick PBS into multiple thin PBS layers arranged in sequence. Each layer has a thickness of 5mm or less, and multiple layers work together to handle large aperture light while keeping individual optical paths short, thus maintaining high transmittance
Solution Approach 2:
The patent changes the arrangement from a single thick element in the optical path direction to multiple thin elements arranged in sequence along the optical path, effectively distributing the aperture handling function across multiple dimensions while keeping each element's thickness small
2Area of stationary object
If the MacNeille PBS is increased in thickness to be suitable for entering light of a large aperture, then the aperture compatibility is improved, but heat generation occurs
Solution Approach 1:
By segmenting the thick PBS into multiple thin layers, the patent reduces the optical path length in each layer, thereby reducing absorption losses and heat generation in each individual layer while collectively handling large aperture light
3Temperature
If the optical path is shortened to reduce heat generation, then heat generation is reduced, but the aperture compatibility may be compromised
Solution Approach 1:
The patent combines multiple thin PBS layers to achieve the collective functionality of a single thick PBS for large aperture handling, while each individual layer maintains a short optical path that reduces heat generation
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 achieves a shorter optical path, reduces heat generation, and enhances light transmittance with less light loss, improving projector performance and reliability.
Implementation Method 1
The MacNeille PBS is a polarizing beam splitter utilizing a Brewster's angle
Data Source
AI summary
A polarizing beam splitter according to the present disclosure includes a transparent optical member, at least one first polarizing beam splitting film, and at least one second polarizing beam splitting film. The at least one first polarizing beam splitting film is disposed inside the transparent optical member to be tilted at a first tilt angle with respect to a first axis. The first axis is parallel to entering light. The at least one second polarizing beam splitting film is disposed inside the transparent optical member to be tilted at a second tilt angle with respect to the first axis. The second tilt angle is in a direction opposite to that of the first tilt angle.