Image Pickup Optical System Using Dual Reflection Prisms
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Solution Overview
Problem
Existing image pickup optical systems face challenges in achieving high optical performance and reduced thickness to accommodate image pickup elements with increased pixel counts, particularly due to the limitations of single and double reflection prism configurations which fail to adequately correct aberrations and reduce thickness effectively.
Innovation Solution
An image pickup optical system utilizing two reflection prisms that bend incident light at almost a right angle, with specific optical axis configurations and power groups, including positive and negative power lenses, to correct aberrations and minimize thickness, while incorporating a lens element and an infrared-cut filter to enhance optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If one reflection prism is used to bend the optical path, then the optical structure thickness is reduced, but the aberration correction capability is insufficient
Solution Approach 1:
The patent divides the aberration correction function into multiple segments by introducing separate lens elements (first lens element for astigmatism correction, second lens element for chromatic aberration correction) in addition to the reflection prism. This segmentation allows each component to specialize in correcting specific aberrations, achieving comprehensive correction while maintaining compact thickness.
Solution Approach 2:
The patent employs a composite optical system combining reflection prism and refractive lens elements. The reflection prism provides primary aberration correction through its angled surfaces, while the lens elements supplement with additional correction capabilities. This composite approach leverages the complementary strengths of different optical mechanisms to achieve superior aberration correction in a compact form factor.
2Length of stationary object
If two reflection prisms are used to bend the optical path twice, then the optical structure thickness is reduced, but the aberration correction is insufficient for high-resolution imaging
Solution Approach 1:
The patent segments the optical correction functions by placing dedicated lens elements between the reflection prisms. The first lens element specifically addresses astigmatism, while the second lens element targets chromatic aberration. This functional segmentation enables precise correction of aberrations that would otherwise degrade image quality on high-resolution sensors.
Solution Approach 2:
The patent optimizes the optical parameters of the lens elements, including their focal lengths, curvatures, and positions, to achieve precise aberration correction. By carefully adjusting these parameters, the system corrects astigmatism and chromatic aberration while maintaining the compact thickness provided by the two-reflection-prism configuration.
3Measurement precision
If the image pickup element size is increased to accommodate more pixels, then the resolution is improved, but the optical structure thickness increases
Solution Approach 1:
The patent redirects the optical path through angled reflection prisms, changing the spatial dimension in which the light travels. This allows the optical elements to be arranged in a compact footprint while maintaining the necessary optical path length and image pickup element size for high-resolution imaging. The angled geometry enables the system to accommodate larger sensors without proportionally increasing overall thickness.
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 achieves high optical performance capable of handling increased pixel counts, reduces the overall thickness of the optical structure, and corrects aberrations such as astigmatism and chromatic aberration, enabling compact and efficient digital equipment design.
Implementation Method 1
two reflection prisms for bending incident light at an almost right angle
Implementation Method 2
a lens element forming at least one power group on an optical path between the two reflection prisms
Data Source
AI summary
An image pickup optical system OP includes first and second prisms P1, P2 for bending incident light at an almost right angle. Optical axis AX at the incident surface of first prism P1 and optical axis AX at the outgoing surface of second prism P2 are almost parallel with each other. There is a lens element forming at least one power group on the optical path between first and second prisms P1, P2, wherein a power group closest to the incident surface of second prism P2 is a positive power group. The incident surface of second prism P2 has a concaved surface shape facing the object side, and the following conditional expressions are satisfied: −4.2<fp2/f<−0.2 (fp2: a focal length of the second prism, f: is a focal length of the entire image pickup optical system), and 0.2<|f_1p/fp2|<1.5 (f_1p: a focal length of the power group closest to the incident surface of the second prism).