Optical Filter for Day and Night Imaging
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Solution Overview
Problem
Conventional imaging devices, such as surveillance cameras, are unable to capture images under night vision conditions due to the presence of an infrared cut filter, which blocks infrared light, preventing effective image capture during night vision applications.
Innovation Solution
An optical filter with a transparent substrate and a filter group that combines a first filter with transmission characteristics in the visible and infrared regions, along with multiple filters having blocking characteristics in specific bands, allowing for transmission in both visible and infrared regions, enabling image capture during the day and at night.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an infrared cut filter is provided to prevent infrared light from reaching the imaging element, then image quality approximating human eye perception is improved, but the ability to capture images under night vision conditions is lost
Solution Approach 1:
The optical filter is segmented into multiple wavelength bands with different transmission characteristics. The filter group includes filters that transmit visible light (400-700nm) and specific infrared bands (800-1000nm, 1500-1800nm) while blocking other infrared regions, enabling selective wavelength transmission for different imaging conditions
Solution Approach 2:
The filter configuration is designed to be dynamically adaptable to different imaging conditions. By using multiple filters with overlapping blocking bands of 150nm or less, the system can transmit both visible light for daytime imaging and specific infrared bands for nighttime imaging, achieving dynamic versatility
2Device complexity
If a single filter is used to transmit both visible and infrared light, then device complexity is reduced, but the ability to selectively block specific infrared bands is lost
Solution Approach 1:
Multiple filters with different transmission and blocking characteristics are combined into a single filter group. The first filter transmits visible light and one infrared band, while additional filters transmit visible light and other infrared bands with overlapping blocking regions, merging their functions into one integrated component
Solution Approach 2:
The filter group uses composite filter structures with multiple layers and materials to achieve complex wavelength-dependent transmission characteristics. Each filter in the group contributes specific optical properties that, when combined, create the desired multi-band transmission and blocking pattern
3Object-affected harmful factors
If the blocking bands of filters are made wide to ensure complete infrared blocking, then blocking effectiveness is improved, but the ability to transmit desired infrared bands for night vision is reduced
Solution Approach 1:
The filter group implements local quality by creating narrow blocking bands (150nm or less) at specific infrared wavelengths while maintaining transmission in other infrared regions. This allows targeted blocking of unwanted infrared light while preserving transmission of desired infrared bands for night vision imaging
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 allows for image capture under both natural light and night vision conditions by providing transmission characteristics in the visible and infrared regions, accommodating the wavelengths of infrared LED lamps for night image capture.
Implementation Method 1
a filter group formed on the transparent substrate and having transmission characteristics over two wavelength bands consisting of a visible region and an infrared region
Implementation Method 2
having blocking characteristics in a band between the visible region and the other band of the infrared region
Data Source
AI summary
An optical filter 13 is provided with a quartz plate 2 and a filter group 3. The filter group 3 is constituted by combining a first filter 33 having transmission characteristics in the visible region and one preset band of the infrared region that is contiguous with the visible region, and a second filter 35 and a third filter 36 each having transmission characteristics in the visible region and another preset band of the infrared region that is removed from the visible region and having blocking characteristics in a band between the visible region and the other band of the infrared region. In the second filter 35 and the third filter 36, each of the bands in which blocking characteristics are obtained is approximately 150 nm or less, and the bands in which blocking characteristics are obtained overlap.