Aspheric Imaging Lens for Compact Near-Infrared DMS Cameras
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Solution Overview
Problem
Existing imaging lenses for driver monitoring systems (DMS) face challenges in providing good imaging quality under near-infrared light conditions while being miniaturized and cost-effective, and they struggle to maintain performance under varying temperatures.
Innovation Solution
The use of three aspheric lenses, including one glass lens, with specific optical configurations and arrangements to achieve high transmittance and field of view, along with temperature stability, while minimizing size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the lens diameter is reduced for miniaturization, then the device size is reduced, but the imaging quality and field of view deteriorate
Solution Approach 1:
The patent employs aspheric surfaces on multiple lens elements (first lens, second lens, and third lens) to correct optical aberrations and expand the field of view. The aspheric coefficients are specifically optimized to achieve a field of view greater than 80 degrees while maintaining compact lens dimensions, directly resolving the contradiction between miniaturization and imaging quality.
2Measurement precision
If the transmittance is increased for near-infrared light, then the imaging capability is improved, but the temperature drift increases
Solution Approach 1:
The patent optimizes the material parameters of the lens elements, specifically selecting materials with appropriate refractive indices and dispersion characteristics for near-infrared transmission. The aspheric coefficients and lens curvature parameters are adjusted to achieve high transmittance at 940 nm wavelength while minimizing temperature-induced focal shift and aberration changes, thereby maintaining imaging quality across temperature variations.
3Adaptability or versatility
If the field of view is increased for better monitoring coverage, then the monitoring capability is improved, but the lens size increases
Solution Approach 1:
The patent uses aspheric lens surfaces with optimized coefficients to achieve a field of view exceeding 80 degrees within a compact lens structure. The aspheric geometry allows for enhanced light gathering and wider angular coverage without requiring proportionally larger lens diameters, thus achieving wide-field monitoring with miniaturization.
Solution Approach 2:
The patent employs multiple lens elements with different aspheric coefficients arranged in sequence along the optical axis. This multi-element aspheric configuration achieves wide field of view by manipulating light paths through dimensional arrangement rather than simply increasing individual lens sizes, maintaining compact overall dimensions while expanding monitoring coverage.
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 solution provides an imaging lens with high transmittance and field of view, effectively addressing imaging quality and temperature drift issues, while being compact and cost-effective.
Implementation Method 1
The first lens is an aspheric glass lens with a positive refracting power. The second lens and the third lens are two aspheric lenses.
Data Source
AI summary
An imaging lens including an aperture stop, a first lens, a second lens and a third lens sequentially arranged along an optical axis from an object side to an image side is provided. The first lens is an aspheric glass lens and has positive refracting power. The second lens is an aspheric plastic lens. The third lens is an aspheric plastic lens. The imaging lens has the transmittance higher than 85% for light with a wavelength of 940 nm and has the field of view less than 90 degrees.