Folded Imaging Optics With Phase Shifters for Compact Zoom Quality
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Solution Overview
Problem
Imaging optical systems for image pickup apparatuses face challenges in achieving a reduced size while maintaining high optical performance and correcting aberrations, particularly in zoom lenses with large aperture diameters.
Innovation Solution
The use of transmissive reflective surfaces and phase shifters, such as quarter waveplates, in a magnification-varying optical system with a configuration that includes a first and second lens unit with negative and positive refractive powers, respectively, along with specific aberration correction methods to maintain high image quality and reduce system size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the aperture diameter is increased to achieve high magnification and better light gathering, then the image quality and magnification capability are improved, but the overall size of the optical system increases
Solution Approach 1:
The patent employs a nested optical path configuration where the optical system is folded back on itself, with the light path returning through previously traversed regions. This nesting allows the effective optical path length to be extended while keeping the physical footprint compact, thereby achieving high magnification without proportionally increasing the overall system volume.
Solution Approach 2:
The patent transitions from a linear optical path to a three-dimensional folded configuration by introducing reflective surfaces at angles. This dimensional change allows the light to traverse a longer effective path through the aperture while the physical envelope remains compact, resolving the contradiction between aperture utilization and system size.
2Reliability
If transmissive reflective surfaces and phase shifters are added to correct chromatic and other aberrations, then the optical performance is improved, but the device complexity increases
Solution Approach 1:
The patent combines multiple functions into the lens elements themselves. The transmissive reflective surfaces are integrated directly onto lens surfaces, and phase shifters are incorporated as coatings or embedded layers within the lens structure. This merging eliminates the need for separate components, thereby improving optical performance while minimizing the increase in device complexity.
Solution Approach 2:
The lens units in the patent serve multiple functions simultaneously: they provide the primary refractive power for image formation, incorporate transmissive reflective surfaces for aberration correction, and include phase shifters for chromatic aberration control. This multi-functionality reduces the overall component count and simplifies the system architecture while achieving high optical performance.
3Volume of moving object
If a folded optical path with transmissive reflective surfaces is used to reduce system size, then the compactness is improved, but the manufacturing precision requirements increase
Solution Approach 1:
By integrating the transmissive reflective surfaces directly onto the lens surfaces during the lens manufacturing process, the patent eliminates the need for separate alignment of reflective components. The reflective coating is applied precisely where needed on the lens curvature, ensuring automatic optical alignment and reducing manufacturing complexity despite the folded path configuration.
Solution Approach 2:
The patent incorporates the transmissive reflective surfaces and phase shifters during the initial lens manufacturing and coating processes, rather than assembling them as separate components later. This preliminary integration ensures precise positioning and alignment are built into the lens structure itself, reducing the stringency of final assembly tolerances.
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 effectively corrects chromatic and other aberrations, allows for high magnification, and reduces the overall size of the imaging optical system, facilitating easier manufacturing and assembly.
Implementation Method 1
an imaging optical system includes a plurality of lens units, a first transmissive reflective surface, and a second transmissive reflective surface
Implementation Method 2
phase shifters, such as quarter waveplates
Data Source
Figure 1~2
Figure 3
Figure 4A~4B
AI summary
An imaging optical system includes a plurality of lens units. Each distance between adjacent lens units among the plurality of lens units changes during zooming. The plurality of lens units include a first lens unit (L1) with negative refractive power and a second lens unit (L2) with positive refractive power disposed closer to an image plane than the first lens unit, and a first transmissive reflective surface (HM1) and a second transmissive reflective surface (HM2) disposed closer to the image plane than the first transmissive reflective surface.