Composite Optical Filter for Angle-Stable Near-Infrared Shielding
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Solution Overview
Problem
Existing optical filters for imaging devices suffer from spectral transmittance curves that shift significantly with varying incident angles, affecting the transmittance of visible and near-infrared light, leading to inconsistent image quality and color reproducibility.
Innovation Solution
An optical filter comprising a light-absorbing material X700L with a maximum absorption wavelength over 700 nm, a light-absorbing material Y970S with a maximum absorption wavelength under 970 nm, and a dielectric multilayer film, designed to maintain excellent transmittance for visible and specific near-infrared light while effectively shielding other near-infrared light, with minimal shift in spectral curves at high incident angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a dielectric multilayer film is used for near-infrared light shielding, then shielding properties in the near-infrared region are improved, but spectral transmittance curve shifts occur at high incident angles causing deterioration in shielding performance
Solution Approach 1:
The patent combines a dielectric multilayer film with a light-absorbing material layer to create a composite optical filter. The dielectric multilayer film provides reflection-based shielding for near-infrared light, while the light-absorbing material layer provides absorption-based shielding. This composite structure compensates for the spectral curve shifts that occur in dielectric multilayer films at high incident angles, maintaining stable shielding performance across different angles.
Solution Approach 2:
The patent introduces a light-absorbing material layer with specific optical characteristics (absorption spectrum and transmittance properties) to modify the overall optical response of the filter. By changing the optical parameters of the filter system through this additional layer, the patent compensates for angle-dependent shifts in the dielectric multilayer film's reflection characteristics.
2Stability of the object's composition
If absorbing material is used to reduce shift in visible light transmission region, then visible light transmittance stability is improved, but near-infrared light transmission region shift cannot be reduced
Solution Approach 1:
The patent applies different optical characteristics to different wavelength regions by using a light-absorbing material with specific spectral properties. The absorbing material is designed to have minimal absorption in the visible light region (420-650 nm) to maintain stable visible light transmittance, while providing strong absorption in the near-infrared region (710-950 nm) to maintain stable near-infrared shielding. This local differentiation of optical properties resolves the contradiction.
3Adaptability or versatility
If incident angle increases, then field of view is improved, but spectral transmittance curve shifts cause color reproducibility deterioration
Solution Approach 1:
The patent converts the harmful effect of incident angle-induced spectral shifts into a beneficial outcome by carefully designing the light-absorbing material layer to compensate for these shifts. The absorbing material's optical characteristics are selected specifically to counteract the wavelength-dependent reflection changes in the dielectric multilayer film at oblique angles, thereby maintaining color reproducibility while allowing increased field of view.
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 filter provides stable transmittance and shielding properties across varying angles, ensuring consistent image quality and color reproducibility by minimizing the shift in spectral curves, particularly in the near-infrared light region, even at high incident angles.
Implementation Method 1
a light-absorbing material X700L having a maximum absorption wavelength in a wavelength region longer than 700 nm
Implementation Method 2
a light-absorbing material Y970S having a maximum absorption wavelength in a wavelength region shorter than 970 nm
Implementation Method 3
an optical filter including a dielectric multilayer film, in which the optical filter satisfies all of the following spectral characteristics
Implementation Method 4
since an optical film thickness of the dielectric multilayer film changes depending on an incident angle of light, there is such a problem that a spectral transmittance curve changes depending on the incident angle
Data Source
AI summary
An optical filter includes: a light-absorbing material X700L having a maximum absorption wavelength in a wavelength region longer than 700 nm; a light-absorbing material Y970S having a maximum absorption wavelength in a wavelength region shorter than 970 nm; and a dielectric multilayer film, in which the optical filter satisfies all of spectral characteristics (i-1) to (i-4).