Diffractive Optical Element Cemented Lens Weight Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing optical systems for image pickup apparatuses, such as cameras, face challenges in reducing weight while maintaining effective aberration correction, particularly in telephoto lenses where chromatic aberrations increase with reduced size and longer focal length.
Innovation Solution
The optical system incorporates a front lens unit consisting of a positive lens and a diffractive optical element, where the diffractive optical element is cemented with at least one diffractive surface, and the interval between the positive lens and the diffractive optical element is maximized, along with an aspherical lens configuration to reduce weight and correct chromatic aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the optical system uses conventional lens configuration with reduced size and longer focal length, then the telephoto lens achieves compact design, but chromatic aberrations increase
Solution Approach 1:
The patent combines a positive lens made of one type of optical material with a diffractive optical element made of a different material structure (grating pattern), creating a composite optical system. This composite structure allows the positive lens to provide converging power while the diffractive element introduces negative dispersion to correct chromatic aberrations, enabling compact telephoto design without sacrificing optical performance
Solution Approach 2:
The patent changes the optical parameters by introducing a diffractive optical element with specific grating constants and diffraction orders. By controlling the diffractive parameters (grating depth, period, and profile), the system achieves wavelength-dependent phase modulation that corrects chromatic aberrations while maintaining the compact form factor required for telephoto applications
2Reliability
If the optical system uses more lenses and complex configuration, then aberration correction improves, but lens weight increases
Solution Approach 1:
The patent merges the functions of multiple optical elements into a single integrated front lens unit. The positive lens and diffractive optical element are combined in close proximity (with air gap less than 5mm), effectively replacing what would traditionally require multiple separate lenses and correction elements. This merging reduces the number of optical components and overall lens weight while maintaining comprehensive aberration correction capabilities
Solution Approach 2:
The front lens unit serves multiple functions simultaneously: the positive lens provides primary converging power for telephoto focal length, while the diffractive optical element corrects chromatic aberrations, spherical aberrations, and coma. This multi-functional design eliminates the need for separate correction lenses, reducing overall lens weight and complexity
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 effectively reduces the weight of the optical system while satisfactorily correcting chromatic and various aberrations, achieving a compact and optically superior telephoto lens design.
Implementation Method 1
a diffractive optical element which are arranged in order from the object side to the image side, wherein the diffractive optical element consists of a plurality of lenses that are cemented to each other, and at least one of cemented surfaces of the plurality of lenses is a diffractive surface
Data Source
AI summary
Provided is an optical system including, in order from an object side to an image side, a front lens unit, an aperture stop, and a rear lens unit. The front lens unit consists of a positive lens and a diffractive optical element, which are arranged in order from the object side to the image side. The diffractive optical element consists of a plurality of lenses that are cemented to each other, and at least one of cemented surfaces of the plurality of lenses is a diffractive surface. An interval on an optical axis between the positive lens and the diffractive optical element is the largest among intervals on the optical axis between two lenses that are adjacent in the optical system.