Folded Polarization Optical Layout for Compact Imaging
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Solution Overview
Problem
Existing optical systems face challenges in achieving a compact size while maintaining high optical performance, particularly in reducing the size perpendicular to the optical axis and ensuring a large light receiving element with good optical performance.
Innovation Solution
An optical system comprising a first and second transmissive reflective surface with a quarter waveplate, where light follows a specific path through these elements to satisfy conditional expressions that ensure compactness and high optical performance, using polarization selective transmissive reflective elements and quarter waveplates to manage light polarization effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a periscope optical system is used to reduce overall optical length, then the optical system becomes more compact in the optical axis direction, but the size perpendicular to the optical axis cannot be reduced
Solution Approach 1:
The patent uses a transmissive reflective surface that transmits light in a first direction (optical axis) and reflects light in a second direction perpendicular to the first. This dual-directional optical control allows the light to travel a longer effective path while maintaining a compact physical footprint in both the optical axis direction and the perpendicular direction, thereby reducing the overall size in multiple dimensions simultaneously
2Length of stationary object
If a catadioptric optical system is used, then the optical path is folded to reduce size, but it is difficult to make the light receiving element large relative to the transparent hole in the primary mirror
Solution Approach 1:
The transmissive reflective surface enables the optical path to be folded in a manner that decouples the relationship between the primary mirror aperture size and the light receiving element size. By utilizing the perpendicular reflection direction, the system can accommodate a larger light receiving element without requiring a proportionally larger primary mirror transparent hole
Solution Approach 2:
The patent changes the optical configuration from conventional catadioptric design to one using transmissive reflective surfaces with specific transmission and reflection characteristics. This parameter change in the optical path management allows independent optimization of the light receiving element size relative to the primary mirror aperture
3Reliability
If conventional optical systems are used, then good optical performance can be achieved, but the overall system size is large
Solution Approach 1:
The transmissive reflective surface utilizes three-dimensional spatial control of light, transmitting in the optical axis direction and reflecting in the perpendicular direction. This allows the optical system to achieve good imaging performance while maintaining a compact size by efficiently utilizing available space in multiple dimensions
Solution Approach 2:
The transmissive reflective surface performs multiple functions simultaneously: it acts as both a transmission element for on-axis light and a reflection element for off-axis light. This multi-functionality reduces the need for separate optical components, thereby compacting the overall system while maintaining optical performance
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 system achieves a compact design with high optical performance by optimizing the optical path length and reducing aberrations, ensuring a large image circle and effective light utilization, thereby improving image quality and reducing ghost light.
Implementation Method 1
a quarter waveplate
Implementation Method 2
first transmissive reflective surface and a second transmissive reflective surface
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
[SOLUTION MEANS] An optical system 100 includes, in order from an object side to an image side, a first transmissive reflective surface HM1, a quarter waveplate QWP, and a second transmissive reflective surface HM2. The optical system is a primary imaging system. Light from the object side transmits through the first transmissive reflective surface and the quarter waveplate in this order, is reflected by the second transmissive reflective surface towards the object side, transmits through the quarter waveplate, is reflected by the first transmissive reflective surface towards the image side, transmits through the quarter waveplate and the second transmissive reflective surface in this order, and travels towards the image side. A distance zm1 on an optical axis from the first transmissive reflective surface to an image plane, and a focal length f of the optical system satisfy a predetermined conditional expression.