Light Guide Optics for Beam Shaping in Distance Measurement

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Solution Overview

Problem

Existing distance measuring apparatuses face challenges in achieving accurate distance measurement due to the spread angle differences of illumination light between horizontal and vertical directions, leading to complications in shaping the illumination light and increased possibility of unnecessary light scattering, which degrades measurement accuracy.

Innovation Solution

An optical apparatus with a light guide unit having a first surface for incident illumination light and a second surface with a transmissive region and a reflective region, where the surfaces are non-parallel, allowing the illumination light to be shaped without passing through additional surfaces, reducing unnecessary light and maintaining measurement accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If illumination light is reflected by the outer surface of a prism, then the apparatus configuration is simple, but it is difficult to shape the illumination light

Engineering Contradiction:
Improveapparatus configurationVSAvoidillumination light shaping
Core Design Contradiction:
Device complexityVSShape

Solution Approach 1:

The second surface of the light guide unit is divided into a transmissive region and a reflective region. The transmissive region allows illumination light to pass through to the deflection unit, while the reflective region reflects return light to the light receiving element. This segmentation enables both simple apparatus configuration and effective illumination light shaping without requiring additional optical elements.

Inventive Principle:
Principle #1Segmentation

2Shape

If illumination light is reflected by the inner surface of a prism, then the illumination light can be shaped, but part of the illumination light is scattered by scratches and foreign objects on optical surfaces

Engineering Contradiction:
Improveillumination light shapingVSAvoiddistance measurement accuracy
Core Design Contradiction:
ShapeVSMeasurement precision

Solution Approach 1:

The patent extracts the light shaping function from multiple prism surfaces and concentrates it into a single light guide unit with non-parallel first and second surfaces. The illumination light enters through the first surface and exits through the transmissive region of the second surface after passing through only these two surfaces, minimizing scattering from scratches and foreign objects while maintaining effective light shaping capability.

Inventive Principle:
Principle #2Taking out (Extraction)

3Shape

If illumination light passes through many optical surfaces of the prism, then the illumination light can be shaped, but unnecessary light is scattered and incident on the light-receiving element

Engineering Contradiction:
Improveillumination light shapingVSAvoidunnecessary light scattering
Core Design Contradiction:
ShapeVSObject-generated harmful factors

Solution Approach 1:

The second surface of the light guide unit has different local properties: the transmissive region has high transmission quality for illumination light, while the reflective region has high reflection quality for return light. This local quality differentiation ensures that illumination light is shaped effectively while minimizing unnecessary light scattering to the light receiving element, as each region is optimized for its specific function.

Inventive Principle:
Principle #3Local quality

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

The solution enables accurate distance measurement by shaping the illumination light effectively and minimizing unnecessary light, ensuring high detection accuracy even at long distances without increasing the complexity or size of the apparatus.

Implementation Method 1

a second surface including a transmissive region through which the illumination light from the first surface is transmitted

Methodology Applied
Scientific EffectLight transmission: Light

Implementation Method 2

a reflective region that reflects the return light from the deflection unit

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 3

the first and the second surfaces are non-parallel to each other, and wherein the illumination light from the first surface is incident on the transmissive region without being transmitted or reflected by other surfaces

Methodology Applied
Scientific EffectLight refraction: Refraction

Data Source

PatentEP3919859B1Optical device, and on-vehicle system and mobile device including optical device
Publication Date: 2024.10.09 CANON KK
  • EP3919859B1 patent drawingFigure 1
  • EP3919859B1 patent drawingFigure 2
  • EP3919859B1 patent drawingFigure 3

AI summary

An optical apparatus 1 includes a deflection unit 30 configured to deflect illumination light from a light source 11 to scan an object 100 and deflect reflected light from the object 100, and a light guide unit 20 configured to guide the illumination light from the light source 11 to the deflection unit 30 and guide the reflected light from the deflection unit 30 to a light-receiving element 43, wherein the light guide unit 20 includes a first surface 211 on which the illumination light from the light source 11 is incident and a second surface 212 including a transmissive region 2121 through which the illumination light from the first surface 211 is transmitted and a reflective region 2122 that reflects the reflected light from the deflection unit 30, wherein the first and the second surfaces 211 and 212 are non-parallel to each other, and wherein the illumination light from the first surface 211 is incident on the transmissive region 2121 without passing through other surfaces.