Optical System Polarization Management for Projector Contrast
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Solution Overview
Problem
Existing optical systems for projectors face challenges in increasing contrast due to orthogonal polarization states from light valves, which limits the effectiveness of post-polarizers and results in reduced contrast and light use efficiency, especially when dealing with blue light, which is detrimental to light valves.
Innovation Solution
An optical system with a first optical element having divided regions for different polarization actions at a pupil position and a second optical element with similar divisions conjugate to the first, allowing for improved polarization alignment and contrast through pupil conjugation, enabling efficient wavelength separation and light modulation by multiple light valves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If two light valves are used to extend the lives of the light valves by splitting blue light, then the duration of action of light valves is improved, but the contrast is worsened due to orthogonal polarization states
Solution Approach 1:
The blue light beam is divided into two separate beams that are directed to different light valves. This segmentation allows the blue light exposure to be distributed across multiple light valves, extending their operational life while maintaining the ability to achieve high contrast through the optical system's polarization management
Solution Approach 2:
A polarization beam splitter and quarter-wave plates are introduced as intermediary optical elements between the light source and light valves. These intermediaries convert the orthogonal polarization states into a configuration where a post-polarizer can effectively increase contrast while still distributing blue light across multiple valves
2Duration of action of stationary object
If a blue light beam is simply split into two, then the life of light valves is extended, but it is difficult to increase contrast
Solution Approach 1:
The polarization state parameter of the light beams is changed through the use of quarter-wave plates and polarization beam splitters. By transforming the orthogonal polarization states into a different configuration, the system enables effective contrast enhancement while maintaining the extended light valve life benefit
3Quantity of substance
If orthogonal polarization states are used from light valves, then blue light can be distributed to multiple valves, but the effectiveness of post-polarizers is reduced resulting in lower contrast
Solution Approach 1:
Optical intermediaries including polarization beam splitters and quarter-wave plates are positioned in the optical path to transform the polarization states. These intermediaries enable the system to maintain blue light distribution while creating a polarization configuration that works effectively with post-polarizers for contrast enhancement
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 enhances contrast and light use efficiency by aligning polarization directions, reducing blue light exposure on light valves, and maintaining high wavelength separation efficiency, thereby extending the life of the optical system and improving image quality.
Implementation Method 1
a first optical element having a plurality of divided regions having mutually different polarization actions
Implementation Method 2
generates illumination light including a plurality of color light beams in mutually different wavelength bands
Data Source
AI summary
An optical system of the present disclosure includes: a first optical system that includes a first optical element having a plurality of divided regions having mutually different polarization actions, the first optical element being disposed at a first pupil position in the optical system, and that generates illumination light including a plurality of color light beams in mutually different wavelength bands; a plurality of light valves that each modulates at least one color light beam of the plurality of color light beams included in the illumination light; and a second optical system that includes a second optical element having a plurality of divided regions having mutually different polarization actions, the second optical element being disposed at a second pupil position conjugate to the first pupil position, and on which the plurality of color light beams modulated by the plurality of light valves is incident.