Zoom Lens Light-Path Separation for Compact Relay Optics

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Solution Overview

Problem

Existing zoom lenses with separation elements face issues of reduced optical performance and increased size due to the separation element's impact on the light path, leading to potential downsizing challenges.

Innovation Solution

The zoom lens design incorporates specific refractive power ratios and lens configurations, including a separation element that branches the light path into transmitted and reflected paths, with optimized focal length and Abbe number relationships, to maintain high optical performance while minimizing the relay unit's size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a separation element is introduced to branch the light path for additional functions, then the functionality of the zoom lens is improved, but the optical performance deteriorates and the size increases

Engineering Contradiction:
ImprovefunctionalityVSAvoidoptical performance
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent branches the light path into two dimensions: a transmitted light path for the main imaging function and a reflected light path for additional functions such as autofocus detection. By using a beam splitter that separates light in different directions rather than adding sequential components, the system achieves multi-functionality without compromising the main optical path's performance.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

A beam splitter is introduced as an intermediary component that divides the incoming light into transmitted and reflected paths. This mediator allows the system to simultaneously serve multiple functions while maintaining optical quality in both paths, resolving the contradiction between added functionality and maintained optical performance.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If a separation element is introduced to branch the light path for additional functions, then the functionality of the zoom lens is improved, but the size of the zoom lens increases

Engineering Contradiction:
ImprovefunctionalityVSAvoidsize
Core Design Contradiction:
Adaptability or versatilityVSVolume of moving object

Solution Approach 1:

Instead of adding components that extend the optical path length, the patent uses a beam splitter to redirect light in a different spatial dimension (reflected path). This allows additional functions to be achieved without proportionally increasing the overall size of the zoom lens system.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Volume of moving object

If the relay unit size is reduced to make the zoom lens compact, then the size is improved, but the optical performance deteriorates due to increased chromatic aberrations

Engineering Contradiction:
Improverelay unit sizeVSAvoidoptical performance
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The patent optimizes the parameters of the relay unit, specifically the focal lengths and Abbe numbers of the lenses, to control chromatic aberrations. By carefully selecting and adjusting these parameters, the system achieves compact relay unit dimensions while maintaining high optical performance through precise parameter optimization.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The relay unit employs a composite lens structure with multiple lens elements having different optical properties (different Abbe numbers and refractive indices). This composite approach allows the system to correct chromatic aberrations while maintaining a compact form factor, as the different lens materials work together to balance optical performance and size.

Inventive Principle:
Principle #40Composite materials

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 a balance between high optical performance and compact size by controlling chromatic aberrations and reducing the relay unit's diameter, thus enhancing the zoom lens's functionality and usability.

Implementation Method 1

a separation element which separates incident light into transmitted light and reflected light in order to branch a light path

Methodology Applied
Scientific EffectLight separation: Reflection

Data Source

PatentEP4194922B1Zoom lens and image pickup apparatus
Publication Date: 2025.10.01 CANON KK
  • EP4194922B1 patent drawingFigure 1A~1B
  • EP4194922B1 patent drawingFigure 2A~2C
  • EP4194922B1 patent drawingFigure 3A~3C

AI summary

A zoom lens (101) includes, in order from an object side, a first lens group (F) of which at least a part moves for focusing, a plurality of lens groups (LZ) which moves in zooming, an aperture stop (SP), and a final lens group (R) which does not move for zooming. The final lens group (R) includes a separation element (PR) for separating an incident light thereon into a transmitted light and a reflected light, a relay unit LR having a positive refractive power on which the transmitted light is incident, and a relay unit LA having a positive refractive power on which the reflected light is incident. An inequality about Fwp/Fw is satisfied, where Fw is a focal length at a wide angle end of the zoom lens (101) via the relay unit LR and FwP is a focal length at the wide angle end of the zoom lens (101) via the relay unit LA.