Thin Imaging Optics with 90-Degree Prism and Zoom Lens Groups
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Solution Overview
Problem
The challenge in embedding a zoom lens into small electronic devices is due to space constraints, as traditional methods like bending the optical axis 90 degrees using a prism or mirror result in thick optical systems, and existing solutions either fail to maintain low ray height or require high accuracy in setup or narrow field angles.
Innovation Solution
An imaging optical system with a lens configuration that includes a first lens group forming an intermediate real image, a second lens group refracting off-axis rays toward the optical axis, and a third lens group relaying the image to the sensor, allowing for magnification adjustment while maintaining a low ray height and thin profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a prism with concave surfaces is used to bend the optical axis, then the ray height entering the prism can be kept low, but the thickness of the prism increases making it difficult to embed in small electronic devices
Solution Approach 1:
The optical axis bending function is segmented from the traditional single-prism structure into multiple lens groups (first, second, and third lens groups) that work together to achieve the same effect. Each lens group contributes to bending the optical axis while maintaining a compact overall thickness, eliminating the need for a thick single prism with concave surfaces.
2Area of stationary object
If a concave lens is included before a prism, then the ray height entering the prism can be kept low, but the total thickness of the optical system increases
Solution Approach 1:
The functions of the concave lens and the prism are merged into an integrated lens group configuration. The first lens group with positive power and the second lens group with negative power work together as a unified optical unit that simultaneously controls ray height and maintains compact thickness, eliminating the need for separate components.
3Volume of moving object
If the optical axis is bent 90 degrees using a prism or mirror, then a zoom lens can be embedded in limited space, but the overall length of the optical system increases to about 20 mm
Solution Approach 1:
Instead of bending the optical axis in a single plane using a prism or mirror, the patent uses multiple lens groups arranged in a three-dimensional configuration that achieves optical axis bending through sequential refraction. This approach distributes the bending function across multiple dimensions, reducing the overall length from 20 mm to a more compact size while maintaining the same volume efficiency.
4Adaptability or versatility
If a zoom lens with zooming ratio of 3 is designed, then magnification adjustment capability is achieved, but the overall length needs to be about 20 mm which is difficult to embed in small devices
Solution Approach 1:
The patent employs movable lens groups (first, second, and third lens groups) that can dynamically adjust their positions along the optical axis to achieve zooming ratio of 3. This dynamic configuration allows magnification adjustment within a compact length by coordinating the movement of multiple lens groups rather than requiring a single long optical path.
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 enables a thin imaging optical system with magnification adjustment capabilities, suitable for small electronic devices, by keeping the ray height low and optimizing the lens configuration to fit within limited spaces.
Implementation Method 1
the first lens group which has positive power and forms an intermediate real image
Implementation Method 2
the second lens group which has positive power and refracts the off-axis ray bundles toward along the optical axis
Implementation Method 3
the third lens group which has positive power and relays the intermediate real image onto the image sensor
Data Source
AI summary
To provide thin imaging optics that have magnification-adjustment functionality and can fit in a small-form-factor electronic device that has limited thickness or layout space. These imaging optics, which have magnification-adjustment functionality that allows magnification adjustment, are characterized in that a prism (P) with the ability to bend the optical axis by 90° is positioned on the object side. These imaging optics are also characterized in that at least the following are laid out, in this order, behind the optical-axis bending means: a positive-power first group (G1) that produces an intermediate image (II), said intermediate image (II) being a real image; a positive-power second group (G2) that refracts off-axis light rays toward a central axis (O); and a positive-power third group (G3) that focuses the intermediate image (II) onto an imaging element. Light-ray heights at the V-edges throughout the imaging optics are thereby kept low.