Piezoelectric Actuated Tunable Lens with Low Wavefront Error
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Solution Overview
Problem
Current optical elements, such as lens assemblies, face challenges in achieving low cost, high volume production with adjustable focal length and high imaging quality, particularly in miniature camera modules where auto focus functionality is required, due to complex designs with movable parts that complicate assembly and optical property optimization.
Innovation Solution
A tunable optical element with piezoelectric actuators that surround the optical axis, allowing for deformation of a bendable cover member to adjust focal length by changing applied voltage, thereby reducing total wavefront error and improving optical properties, even in small optically active areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional movable part designs are used for auto focus lenses, then focal length adjustment is achieved, but device complexity and assembly difficulty increase
Solution Approach 1:
The patent merges the lens element and actuator into a single integrated unit where the actuator is positioned directly behind the lens element. This integration eliminates the need for separate movable parts and complex mechanical assemblies, while still achieving focal length adjustment through direct actuation of the lens element.
Solution Approach 2:
The lens element serves multiple functions: it acts as both the optical element for focusing and the deformable element for focal length adjustment. By making the lens element itself deformable through the integrated actuator, the design eliminates the need for separate adjustment mechanisms.
2Volume of moving object
If optical elements with small optically active area are used, then compact device size is achieved, but optical quality deteriorates
Solution Approach 1:
The patent changes the physical parameters of the optical element by making it deformable. By applying voltage to the integrated actuator, the lens element's curvature and shape can be dynamically adjusted, enabling focal length tuning without changing the physical size of the optically active area. This maintains compact device size while achieving variable optical properties.
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 enables the production of optical elements with low total wavefront error (WFE RMS) below 60 nm, enhancing image quality across a range of focal lengths and voltages, and facilitating integration into compact devices like mobile phones.
Implementation Method 1
one or more piezoelectric actuators arranged for shaping said bendable cover member into a desired shape
Data Source
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AI summary
There is presented an optical element (100, 500, 600, 700) comprising a support structure (101, 501) with a sidewall (112, 512), a bendable cover member (102, 502, 702) attached to the sidewall (112, 512), one or more piezoelectric actuators (103, 104, 105) arranged for shaping said bendable cover member (102, 502, 702) into a desired shape, wherein said optical element (100, 500, 600, 700) comprises an optically active area (111, 511) with an optical axis (110, 510), wherein an outer edge (215A-E) of the one or more piezoelectric actuators (103, 104, 105) as observed in a direction being parallel with the optical axis (110, 510) defines a first line, and an inner edge (109) of the support structure (101, 501) at the interface between the support structure (101, 501) and the bendable cover member (102, 502, 702) as observed in the direction being parallel with the optical axis (110, 510) defines a second line, wherein the first line and the second line as observed in the direction being parallel with the optical axis (110, 510) cross each other in two or more positions and/or are parallel and coincident in one or more positions.