Polarization Conversion Element Light Detection via Beam Splitter
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Solution Overview
Problem
Existing image projection systems face challenges in detecting brightness and color changes from the light source without adding new optical elements, leading to reduced brightness and unstable white balance due to deterioration of fluorescent materials and optical elements under high-intensity laser beams.
Innovation Solution
The use of a PBS array with a second polarization separation film as a detection surface allows for easy installation of a photosensor to detect light without affecting the brightness of the displayed image, by converting unpolarized light into P-polarized light and using a reflection film to rotate the polarization direction, ensuring accurate detection of light intensity and color without unnecessary noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a photosensor is installed to detect light from the light source, then brightness and color changes can be detected, but the installation becomes complex and may shield the effective light flux
Solution Approach 1:
The patent introduces a beam splitter as an intermediary optical element that separates the detection light path from the main illumination path. The beam splitter directs a portion of the light from the light source to the photosensor while allowing the remaining light to proceed to the light modulation element, enabling detection without shielding the effective light flux and simplifying photosensor installation
Solution Approach 2:
The optical system is segmented into separate detection and illumination paths using the beam splitter. This segmentation allows the photosensor to receive light through one path while the main illumination continues through another path, eliminating interference between detection and illumination functions
2Device complexity
If unnecessary light from the light modulation element is received by the photosensor, then the detection system is simple, but the detection accuracy decreases due to image-dependent noise
Solution Approach 1:
The beam splitter acts as a mediator that selectively directs light based on its origin. It transmits light from the light source to the photosensor while blocking light reflected from the light modulation element, thereby eliminating image-dependent noise without complicating the detection system
Solution Approach 2:
The detection system extracts only the necessary light component (light from the light source) while excluding unnecessary light (reflected light from the light modulation element) using the beam splitter, improving detection accuracy by removing image-dependent interference
3Measurement precision
If a hologram element is added to enable light reception by the photosensor, then detection becomes possible, but the brightness of the displayed image reduces
Solution Approach 1:
The beam splitter serves as an intermediary that enables the photosensor to detect light directly from the light source without requiring additional light-modulating elements like holograms, thereby maintaining full brightness of the displayed image while enabling detection capability
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 enables stable detection of light intensity and color, maintaining brightness and white balance over time without adding new optical elements, reducing the impact of high-intensity laser beam deterioration on fluorescent materials.
Implementation Method 1
converting unpolarized light into P-polarized light
Implementation Method 2
using a reflection film to rotate the polarization direction
Implementation Method 3
detect light without affecting the brightness of the displayed image
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
An illumination apparatus comprising a light source (1), a polarization conversion element (4) configured to convert light from the light source into polarized light having a specific polarization direction and to emit the polarized light to an illumination surface, and a photosensor (9) configured to receive light emitted from a surface (10, 16) of the polarization conversion element different from an incident surface (11) and an exit surface (15) of the polarization conversion element, and corresponding image processing apparatus.