Optical Filter Light-Absorbing Layer Angle-Dependent Transmittance
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Solution Overview
Problem
Existing optical filters fail to effectively address the characteristics of light incident at angles greater than 35 degrees and are not compatible with color filters used in imaging apparatuses, leading to uneven coloring of images.
Innovation Solution
An optical filter with a light-absorbing layer that absorbs near-infrared light, maintaining specific transmittance requirements across various incident angles, ensuring compatibility with color filters and preventing image unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional near-infrared cut filter is used, then the filter can block near-infrared light, but the filter causes uneven coloring of images when light incidents at angles greater than 35 degrees
Solution Approach 1:
The patent changes the material parameter by using a light absorber with specific absorption characteristics that is less sensitive to incident angle variations. The light absorber is designed to absorb light in the 730-1100 nm range while maintaining stable transmission characteristics from 0° to 40° incident angles, resolving the contradiction between infrared blocking and color uniformity at large angles
Solution Approach 2:
The patent creates a composite optical filter structure combining a light absorber layer with specific spectral absorption properties and a transparent substrate. This composite structure achieves both effective near-infrared blocking and maintained color uniformity across varying incident angles by integrating materials with complementary optical properties
2Object-affected harmful factors
If the incident angle of light increases, then the optical filter can still block near-infrared light, but the brightness of the image is reduced
Solution Approach 1:
The patent optimizes the absorption spectrum parameters of the light absorber to target specifically the 730-1100 nm near-infrared range while maintaining high transmission in the visible range (400-700 nm). This selective parameter optimization ensures effective infrared blocking without compromising visible light brightness, even at incident angles up to 40°
3Stability of the object's composition
If a dielectric multilayer film is used to eliminate angle dependence, then the wavelength shift is reduced, but the device complexity increases
Solution Approach 1:
The patent extracts and eliminates the dielectric multilayer film component from the filter structure, relying instead on a light absorber with inherently angle-insensitive absorption characteristics. This removal of the complex multilayer structure while maintaining wavelength stability through material selection resolves the contradiction between wavelength stability and device simplicity
4Manufacturing precision
If the optical filter is designed for small incident angles, then the transmission characteristics are optimized, but the filter is not compatible with color filters in wide-angle imaging apparatuses
Solution Approach 1:
The patent designs the light absorber with universal absorption characteristics that remain effective across a wide range of incident angles (0°-40°), making the optical filter compatible with various imaging apparatus configurations including wide-angle lenses and different color filter arrangements. This multi-angle effectiveness provides universality across different imaging systems
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 effectively shields unnecessary light without reducing brightness, even at larger incident angles, and ensures compatibility with color filters, preventing image unevenness in imaging apparatuses.
Implementation Method 1
a light-absorbing layer that includes a light absorber absorbing light in at least a portion of the near-infrared region
Data Source
AI summary
An optical filter (1a) includes a light-absorbing layer (10). The light-absorbing layer absorbs light in at least a portion of the near-infrared region. When light with a wavelength of 300 nm to 1200 nm is incident on the optical filter (1a) at incident angles of 0°, 30°, and 40°, the optical filter (1a) satisfies given transmittance requirements. IEθ1/θ2λ1 to λ2, IAEθ1/θ2λ1 to λ2, and ISEθ1/θ2λ1 to λ2 defined by the following equations (1) to (3) for two incident angles θ1° and θ2° (θ1<θ2) selected from 0°, 30°, and 40° satisfy given requirements in a given domain of a wavelength λ.