Tilt Image Pickup Lens System with Decentering Aberration Control
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Solution Overview
Problem
Image pickup optical systems with tilt mechanisms face challenges in achieving good focus on inclined object planes due to composition shift and increased aberration caused by decentering, limiting the ability to perform fine focusing during tilt image pickup.
Innovation Solution
The optical system incorporates a first lens unit and a second lens unit that move perpendicular to the optical axis, with specific movement and focal length relationships defined by inequalities to minimize composition shift and aberration, allowing for effective tilt image pickup with reduced decentering aberration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a tilt mechanism is used to achieve focus on inclined object planes, then the ability to perform tilt image pickup is improved, but composition shift occurs which impairs convenience
Solution Approach 1:
The optical system divides the lens into multiple lens units (first lens unit with positive refractive power and second lens unit with negative refractive power). Each lens unit can move independently perpendicular to the optical axis, allowing separate control of tilt effect and composition shift. This segmentation enables the first lens unit to generate the desired tilt effect while the second lens unit compensates for composition shift, resolving the contradiction between tilt capability and operational convenience.
2Adaptability or versatility
If lens parts move vertically to generate tilt effect, then tilt image pickup is enabled, but aberration due to optical decentering increases as inclination angle increases
Solution Approach 1:
The patent optimizes specific parameters including the refractive power ratio between lens units (|P1/P2| between 0.3 and 2.0), movement amount ratios (|d1/d2| between 0.3 and 2.0), and positional relationships (0.05 ≤ d1/(d1+d2) ≤ 0.95). These parameter optimizations ensure that aberrations remain controlled even at large inclination angles (up to 45 degrees or more), maintaining optical performance while enabling extensive tilt capability.
Solution Approach 2:
The second lens unit acts as an intermediary that compensates for the aberrations generated by the first lens unit's movement. By moving the second lens unit in the opposite direction with appropriate magnitude, the system counteracts the decentering aberrations, allowing the first lens unit to provide the necessary tilt effect without compromising overall optical quality.
3Measurement precision
If the movement amount of lens parts increases to achieve larger tilt effect, then the correction amount increases, but the amount of decentering aberration increases
Solution Approach 1:
The patent converts the harmful decentering aberration generated by the first lens unit's movement into a beneficial effect by using the second lens unit to compensate. The second lens unit's opposite movement creates an equal and opposite decentering effect that cancels the first lens unit's aberration, transforming the potential harm into a mechanism for achieving large correction amounts without proportional increases in aberration.
Data Source
AI summary
An optical system includes first and second lens units configured to move to have a component of direction perpendicular to an optical axis, in which a sign of an amount of movement of the lens units is defined as negative for a moving direction of the first lens unit and as positive for an opposite direction to the moving direction of the first lens unit, a product of an amount of movement and a focal length of the first lens unit and a product of an amount of movement and a focal length of the second lens unit are different from each other in sign, and Petzval sums of the first and second lens unit, a focal length of the optical system, and a back focus of the optical system are set.