Wavelength-Selective Optical Diffuser for Infrared Image Clarity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing optical diffusers cause diffusion of both human-visible and infrared light, leading to poor image clarity for infrared sensors or cameras behind displays due to uniform light scattering, which hinders detailed image formation.
Innovation Solution
An optical diffuser with distinct scattering rates for visible and infrared wavelengths, allowing high diffusion in the visible range and low diffusion in the infrared range, combined with a reflective polarizer to separate and direct light polarization states, is used to create an optical stack that maintains display uniformity while enabling clear infrared detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If an optical diffuser is used to provide uniform illumination for display, then display uniformity is improved, but infrared image clarity deteriorates due to light scattering
Solution Approach 1:
The optical diffuser is designed with wavelength-dependent scattering properties, providing strong scattering for visible light (450-600 nm) to ensure display uniformity, while providing minimal scattering for infrared light (800-1200 nm) to maintain image clarity. This selective scattering behavior creates different optical qualities for different wavelength ranges within the same component.
Solution Approach 2:
The diffuser's scattering rate parameter R is engineered to have different values for different wavelength ranges. Specifically, the scattering rate R1 for visible light is set to be significantly higher than the scattering rate R2 for infrared light, with R1/R2 ≥ 2. This parameter differentiation allows the same diffuser structure to serve dual purposes.
2Measurement precision
If a reflective polarizer is added to separate polarization states, then infrared detection capability is improved, but optical stack complexity increases
Solution Approach 1:
The reflective polarizer serves multiple functions simultaneously: it separates polarization states to enable infrared detection, maintains display performance by allowing visible light to pass through, and integrates with the existing optical diffuser structure. This multi-functionality reduces the need for additional separate components.
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 achieves uniform illumination for displays while allowing infrared light to pass unaltered to sensors, enhancing image clarity for both visible light display and infrared detection.
Implementation Method 1
the optical diffuser has a first scattering rate R1 for at least one wavelength in the first wavelength range, and a second scattering rate R2 for at least one wavelength in the second wavelength range, such that R1/R2 is greater than or equal to about 2
Implementation Method 2
The first reflective polarizer may transmit at least 40% of light for a first polarization state for each wavelength in the first wavelength range, may reflect at least 70% of light for an orthogonal second polarization state for each wavelength in the first wavelength range
Data Source
AI summary
An optical stack including an optical diffuser and a first reflective polarizer disposed on the optical diffuser is described. For substantially normally incident light and for nonoverlapping first and second wavelength ranges: the optical diffuser has a first scattering rate R1 for at least one wavelength in the first wavelength range, and a second scattering rate R2 for at least one wavelength in the second wavelength range, such that R1/R2 is greater than or equal to 2. The first reflective polarizer may transmit at least 40% of light for a first polarization state for each wavelength in the first wavelength range, may reflect at least 70% of light for an orthogonal 10 second polarization state for each wavelength in the first wavelength range, and transmit at least 40% of light for each of the first and second polarization states and for each wavelength in the second wavelength range.