Imaging Lens Stop Placement for Peripheral Illumination
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Solution Overview
Problem
The challenge is to design an imaging lens that maintains optimal light transmission and optical performance while minimizing size, especially when space between the lens and image plane is restricted, due to the increased incidence angle of principal light rays and the limitations imposed by camera mounts and mechanical parts.
Innovation Solution
The imaging lens is composed of a first lens group and a second lens group with specific refractive power configurations, including a negative lens and a positive refractive power lens component, optimized through conditional expressions to manage back focus, focal lengths, and angles, ensuring efficient light distribution and aberration correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the size of the sensor is increased to capture a wide-range image, then the imaging range is improved, but the light amount at the peripheral portion of the image is reduced due to blockage by the mount and mechanical parts
Solution Approach 1:
The patent changes the spatial arrangement by positioning the aperture stop between the lens groups rather than at the traditional location near the sensor. This dimensional repositioning allows light rays to pass through the aperture stop before reaching the lens groups, preventing blockage by the mount and mechanical parts at the sensor periphery, thereby maintaining high illumination intensity across the entire sensor area including the peripheral portions.
Solution Approach 2:
The aperture stop serves as an intermediary element that mediates the light path between the lens groups and the sensor. By placing the aperture stop in this intermediate position, it controls and directs the light rays to avoid obstruction by the mount and mechanical parts, ensuring sufficient light reaches the peripheral portions of the sensor.
2Volume of moving object
If the incidence angle of principal light ray is increased to reduce lens size, then the device size is reduced, but the light amount at the peripheral portion of the image is reduced due to sensor incidence angle dependence
Solution Approach 1:
The patent repositions the aperture stop to a different spatial location between the lens groups, which fundamentally changes the light path geometry. This dimensional change allows the system to maintain smaller lens sizes while keeping the incidence angle at the sensor within the optimal range, thereby preserving both compact size and high peripheral illumination.
3Volume of moving object
If the space between the imaging lens and image plane is restricted, then the device size is reduced, but the light amount is reduced due to limited space for light path
Solution Approach 1:
The patent utilizes the dimensional space between the lens groups by positioning the aperture stop in this intermediate region rather than at the traditional location near the sensor. This repositioning optimizes the use of available space, allowing sufficient light path clearance within a compact device volume, thereby maintaining high light amount while keeping the device size small.
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
This configuration allows for enhanced light transmission and favorable optical performance without increasing the lens system's size, even under spatial constraints, by reducing the incidence angle of principal light rays and effectively correcting aberrations.
Implementation Method 1
the second lens group includes a negative lens on a side closest to an object, the second lens group includes a lens component having a positive refractive power on a side closest to an image
Data Source
AI summary
The imaging lens consists of, in order from an object side, a first lens group, a stop, and a positive second lens group. The second lens group has a negative lens on a side closest to an object and has a single lens or a cemented lens having a positive refractive power on a side closest to an image. Predetermined conditional expressions relating to a back focus, an incidence angle of a principal light ray on the image plane, a maximum image height, a distance from a lens surface on the side closest to the object to a lens surface on the side closest to the image, a distance from an object side principal point of the second lens group to a stop, and a focal length of the second lens group are satisfied.