Optical Filter with Dual Absorbers for Angle-Independent Transmittance
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Solution Overview
Problem
Existing optical filters do not provide sufficient transmittance for near-infrared light around 850 nm and are affected by incident angle changes, leading to shifts in spectral transmittance curves and affecting the sensitivity of solid state image sensors.
Innovation Solution
An optical filter configuration using a light-absorbing material X800S with a maximum absorption wavelength shorter than 800 nm, a light-absorbing material Y850L with a maximum absorption wavelength longer than 850 nm, and a dielectric multilayer film, which satisfies specific spectral characteristics to ensure high transmittance for visible and specific near-infrared light while shielding other near-infrared light, even at high incident angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a dielectric multilayer film is used to achieve high transmittance for visible light and specific near-infrared light, then the transmittance is improved, but the spectral transmittance curve shifts when the incident angle increases, causing deterioration in shielding regions
Solution Approach 1:
The patent combines a dielectric multilayer film with a resin substrate containing a near-infrared absorbing dye to create a composite optical filter. The dielectric multilayer film provides high transmittance for visible and specific near-infrared light, while the resin substrate with absorbing dye compensates for the angle-dependent spectral shifts, maintaining stable shielding characteristics across different incident angles
Solution Approach 2:
The patent adjusts the optical film thickness of the dielectric multilayer film and the concentration of the near-infrared absorbing dye in the resin substrate to optimize the balance between transmittance and spectral stability. By carefully controlling these parameters, the filter achieves high transmittance while minimizing spectral curve shifts at high incident angles
2Object-affected harmful factors
If the optical film thickness of the dielectric multilayer film is increased to improve shielding properties, then the shielding performance is improved, but the transmittance for visible and near-infrared light decreases
Solution Approach 1:
The patent divides the optical filtering function into two separate components: the dielectric multilayer film responsible for high transmittance through constructive interference, and the resin substrate with absorbing dye responsible for shielding specific near-infrared wavelengths. This segmentation allows each component to be optimized independently for its specific function
Solution Approach 2:
The resin substrate containing the near-infrared absorbing dye acts as an intermediary layer that selectively absorbs specific near-infrared wavelengths while allowing visible light and other near-infrared regions to pass through. This intermediary component provides the shielding function without compromising the transmittance achieved by the dielectric multilayer film
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 optical filter achieves excellent transmittance for visible and specific near-infrared light, effective shielding of other near-infrared light, and minimal shift in spectral curves at high incident angles, thereby enhancing the color reproducibility and sensitivity of solid state image sensors.
Implementation Method 1
a light-absorbing material X800S having a maximum absorption wavelength in a wavelength region shorter than 800 nm
Implementation Method 2
a light-absorbing material Y850L having a maximum absorption wavelength in a wavelength region longer than 850 nm
Implementation Method 3
a dielectric multilayer film
Data Source
AI summary
An optical filter includes: a light-absorbing material X800S having a maximum absorption wavelength in a wavelength region shorter than 800 nm; a light-absorbing material Y850L having a maximum absorption wavelength in a wavelength region longer than 850 nm; and a dielectric multilayer film, in which the optical filter satisfies spectral characteristics (i-1) to (i-5).