Projection Optical System Uniform Light Intensity Distribution

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Solution Overview

Problem

Existing object detection systems, such as vehicle-installed laser radars, fail to achieve a desired intensity distribution of light beams for effective object detection and distance measurement, particularly in ensuring uniform light intensity across the irradiation area.

Innovation Solution

The use of a projection optical system comprising a first optical element with a refractive incidence and exit plane, and a second optical element, such as a cylindrical lens, to distribute and adjust the light beam's intensity distribution, ensuring even illumination across the irradiation area by compensating for light quantity shortages at the edges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If conventional optical systems are used to project light beams for object detection, then the system structure is simple, but the light intensity distribution is non-uniform with shortages at the edges

Engineering Contradiction:
Improvelight intensity distributionVSAvoidoptical system complexity
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The patent introduces optical elements (diffusers, lenses, or reflectors) as intermediary components between the light source and the projection area. These intermediaries modify the light propagation path and intensity distribution, transforming non-uniform light output into uniform illumination across the entire projection area, including edge regions that previously suffered from light shortages.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies optical parameters such as numerical aperture, focal length, and beam divergence angle by selecting specific optical elements. These parameter changes enable precise control over light distribution characteristics, transforming the light intensity profile from non-uniform to uniform while maintaining system feasibility.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If optical elements are added to achieve desired intensity distribution, then the light intensity uniformity is improved, but the device complexity increases

Engineering Contradiction:
Improveintensity distribution uniformityVSAvoidnumber of optical elements
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies optical elements with specific local properties at different positions within the optical path. For example, gradient-index lenses or spatially varying diffusers are used to provide different optical functions in different regions, achieving uniform overall illumination while using relatively simple individual components.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent selects optical elements that perform multiple functions simultaneously. A single lens element may provide both beam shaping and focus control, while a diffuser may simultaneously homogenize intensity and expand beam width. This multi-functionality reduces the total number of components needed.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 desired intensity distribution, including uniform intensity, over the irradiation coverage, enhancing the accuracy and effectiveness of object detection systems by maintaining consistent light intensity across the detection area.

Implementation Method 1

a projection optical system comprising a first optical element (L11, L21) having a refractive incidence and exit plane

Methodology Applied
Scientific EffectRefraction: Refraction

Data Source

PatentEP2808708B1Optical element, projection optical system, and object detector
Publication Date: 2022.10.19 RICOH CO LTD
  • EP2808708B1 patent drawingFigure 1~2
  • EP2808708B1 patent drawingFigure 3~4
  • EP2808708B1 patent drawingFigure 5~6

AI summary

Provided is an optical element (L11, L21) including an incidence plane (S11, S21), and an exit plane (S12, S22) including a plurality of planes that are jointed together. The incidence plane (S11, S21) has a shape based on an angle of divergence of light beam incident upon the incidence plane (S11, S21) and irradiation coverage of light beam exiting from the exit plane (S12, S22).