Optical Filter Light-Absorbing Layer Incident Angle Stability
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Solution Overview
Problem
Existing optical filters fail to effectively block unnecessary light and prevent uneven coloring of images when the incident angle of light is larger than 35°, leading to issues with image quality in imaging apparatuses.
Innovation Solution
An optical filter with a light-absorbing layer that includes a light absorber for the near-infrared region, designed to maintain specific spectral transmittance characteristics across various incident angles, including 0°, 30°, 35°, and 40°, without the use of a dielectric multilayer reflecting layer, ensuring consistent transmission and blocking of light across a wide wavelength range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dielectric multilayer film is used to adjust transmission characteristics, then the dependence on incident angle is reduced for small angles (0°-35°), but the filter fails to effectively block unnecessary light and prevent uneven coloring when the incident angle exceeds 35°
Solution Approach 1:
The patent changes the material parameter from dielectric multilayer film to light-absorbing material with specific absorption coefficients. By selecting materials with appropriate absorption coefficients for different wavelength regions (visible light region and near-infrared region), the filter achieves stable transmission characteristics across a wide incident angle range (0°-60°), resolving the contradiction between small-angle stability and large-angle adaptability
Solution Approach 2:
The patent uses a composite structure combining a transparent substrate with a light-absorbing layer containing specific dyes or pigments. This composite material approach allows the filter to simultaneously achieve high transmittance in the visible region (450-650nm) and effective blocking in the near-infrared region (700-1100nm) across large incident angles, overcoming the limitations of single-material dielectric filters
2Ease of manufacture
If conventional optical filters are used, then manufacturing is simplified, but uneven coloring of images occurs due to spectral variations at large incident angles
Solution Approach 1:
The patent specifies precise parameter ranges for the light-absorbing material (absorption coefficients k1 and k2 at different wavelengths) to achieve uniform spectral transmittance. By controlling these material parameters and the layer thickness (5-50 μm), the filter maintains consistent color characteristics across the visible spectrum even at large incident angles up to 60°, preventing image discoloration while keeping the manufacturing process relatively simple
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 blocks unnecessary light and prevents uneven coloring of images even at larger incident angles, ensuring consistent image quality by maintaining spectral transmittance characteristics and preventing ripples in the transmission spectrum, thus reducing the likelihood of image discoloration.
Implementation Method 1
a light-absorbing layer that includes a light absorber for 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 to 1200 nm is incident on the optical filter (1a) at an incident angle of 0°, the optical filter (1a) satisfies given requirements. When light with a wavelength of 300 to 1200 nm is incident on the optical filter (1a) at incident angles of 0°, 30°, 35°, and 40°, the optical filter (1a) satisfies given requirements related to a normalized spectral transmittance. The normalized spectral transmittance is determined by normalization of a spectral transmittance for each incident angle so that the maximum of the spectral transmittance for each incident angle in the wavelength range of 400 to 650 nm is 100%.