Intermediate-Image Optical System for Compact Wide-Angle Projection
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Solution Overview
Problem
Existing optical systems that form intermediate images are inefficient in space usage and difficult to compactly arrange lenses due to differences in lens diameters and spacings, particularly in retrofocus-type systems with negative-positive refractive power arrangements, leading to challenges in aberration correction and efficient use of space.
Innovation Solution
The optical system includes a first lens group with negative refractive power on the enlargement side and a second lens group with positive refractive power on the reduction side, with an intermediate image tilted towards the enlargement side, and strategically placed stops to reduce lens diameter differences and improve space efficiency, allowing for compact and high-aberration correction performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a retrofocus-type system with negative-positive refractive power arrangement is used to achieve wide angle and long back focus, then the angle of view on the enlargement side increases, but the lens diameter on the enlargement side increases and the difference in diameter between lenses increases, making it difficult to dispose lenses compactly
Solution Approach 1:
The optical system is divided into two separate optical subsystems (first and second) with an intermediate image forming position between them. This segmentation allows independent optimization of each subsystem's refractive power arrangement, enabling the first subsystem to provide wide angle with negative refractive power while the second subsystem compactly arranges positive power lenses, thus resolving the contradiction between wide angle and compact lens arrangement.
Solution Approach 2:
An intermediate image forming position is introduced as a mediator between the two optical subsystems. This intermediate image plane allows the system to reset the optical path, enabling the second optical subsystem to start with positive refractive power closer to the intermediate image, thereby reducing lens diameter differences and improving space efficiency while maintaining the wide-angle capability provided by the first subsystem.
2Reliability
If multiple lenses are disposed in the second optical subsystem with positive refractive power, then aberration correction capability improves, but the spacing between lenses increases and the system becomes less compact
Solution Approach 1:
The invention changes the refractive power parameter arrangement by placing positive refractive power lenses closer to the intermediate image in the second optical subsystem. This parameter change allows multiple lenses to be disposed with smaller spacings while maintaining effective aberration correction, as the positive power arrangement near the intermediate image reduces the diameter differences between successive lenses, enabling more compact lens spacing.
3Device complexity
If the intermediate image is formed on the reduction side of the first optical subsystem, then the optical path is simplified, but the image tends to be tilted toward the reduction side, requiring additional correction
Solution Approach 1:
The second optical subsystem is designed with positive refractive power lenses arranged to produce an image tilt toward the enlargement side, which preliminarily counteracts the tilt toward the reduction side caused by the first optical subsystem. This preliminary anti-action allows the intermediate image to be formed with reduced tilt, simplifying the overall optical path while minimizing the need for additional tilt correction elements.
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 enables a wide-angle optical system that efficiently uses space, is compact, and provides high aberration correction capabilities, suitable for projectors and image pickup apparatuses.
Implementation Method 1
The first lens group includes, on the enlargement side, a first component with negative refractive power. The second lens group that has positive refractive power
Implementation Method 2
the first stop is provided in the vicinity of a position, between the first lens group provided with the negative component and the second lens group with positive refractive power, where peripheral light and center light intersect so that the light flux is concentrated
Implementation Method 3
an enlargement conjugate point on the enlargement conjugate side forms an image at an intermediate image forming position between the first optical system and the second optical system, and the image formed at this intermediate image forming position is reformed at a reduction conjugate point on the reduction conjugate side
Data Source
AI summary
An optical system includes a first optical subsystem disposed on an enlargement side and a second optical subsystem disposed on a reduction side with an intermediate image in between. The first optical subsystem includes: a first lens group that is disposed on the enlargement side of a first stop with a first distance, in which other lenses could be disposed but no other lenses are disposed, and is provided on the enlargement side with a first component with negative refractive power; and a second lens group that has positive refractive power, is disposed on the reduction side of the first stop with a second distance, in which other lenses could be disposed but no lenses are disposed, and forms the intermediate image so as to be adjacent on a reduction side of the second lens group and so as to be tilted toward the enlargement side.