Thermal Radiation Detection Layout for Accurate Low-Temperature Sensing

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Solution Overview

Problem

The accuracy of temperature measurement in laser processing devices is reduced by the influence of environmental temperature, particularly at low temperatures (250°C or less).

Innovation Solution

A thermal radiation light detection device with multiple light detection units and temperature detection units, each attached to different wall portions of the housing, to extract and correct signals based on thermal radiation light of different wavelengths, using condenser lenses to enhance accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a single light detection unit is used to measure temperature, then the device structure is simple, but the measurement accuracy is reduced by environmental temperature influence

Engineering Contradiction:
Improvetemperature measurement accuracyVSAvoiddevice structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The housing is divided into multiple wall portions with light detection units and temperature detection units separately arranged on different walls. This segmentation allows the system to distinguish between thermal radiation from the workpiece and thermal radiation from the housing, enabling accurate temperature measurement while maintaining a relatively simple overall structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Temperature detection units are introduced as intermediary components to detect the thermal radiation from the housing walls. These intermediary sensors provide environmental temperature data that is used to correct the measurements from the light detection units, thereby eliminating the harmful influence of environmental temperature without requiring complex shielding or isolation structures.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If light detection units are attached to the same wall portion, then the device structure is compact, but thermal radiation from that wall enters the detector causing measurement errors

Engineering Contradiction:
Improvetemperature measurement accuracyVSAvoiddevice compactness
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The detection units are segmented and distributed across different wall portions of the housing. This spatial segmentation ensures that thermal radiation from any single wall cannot directly enter the light detection units, as each detector is positioned on a different wall facing a different direction, thus eliminating measurement errors while maintaining compact integration within the housing.

Inventive Principle:
Principle #1Segmentation

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

Enables highly accurate temperature measurement by correcting signal outputs from light detection units using additional temperature detection units, reducing the impact of environmental temperature fluctuations.

Implementation Method 1

a light extraction unit disposed inside housing and configured to extract light of a first wavelength and light of a second wavelength from the thermal radiation light

Methodology Applied
Scientific EffectOptical filtering by wavelength: Filter (optical)

Implementation Method 2

Each of the light detection units includes a condenser lens configured to condense light on the light detection element

Methodology Applied
Scientific EffectLight condensation/focusing: Lens

Implementation Method 3

a first light detection unit attached to a wall portion among the plurality of wall portions and configured to detect the light of the first wavelength; a second light detection unit attached to a wall portion among the plurality of wall portions and configured to detect the light of the second wavelength

Methodology Applied
Scientific EffectPhotoelectric conversion: Photoelectric Effect

Implementation Method 4

a first temperature detection unit attached to a wall portion among the plurality of wall portions, the wall portion to which the first temperature detection unit is attached being different from the wall portion to which the first light detection unit is attached

Methodology Applied
Scientific EffectThermal radiation detection: Thermal Radiation

Data Source

PatentEP4123273B1Thermal radiation light detection device and laser processing device
Publication Date: 2026.04.01 HAMAMATSU PHOTONICS KK
  • EP4123273B1 patent drawingFigure 1
  • EP4123273B1 patent drawingFigure 2
  • EP4123273B1 patent drawingFigure 3

AI summary

A thermal radiation light detection device includes: a housing including a plurality of wall portions; a light entrance unit attached to a wall portion among the plurality of wall portions and configured to cause thermal radiation light to enter the housing; a light extraction unit disposed inside housing and configured to extract light of a first wavelength and light of a second wavelength from the thermal radiation light, the second wavelength being different from the first wavelength; a first light detection unit attached to a wall portion among the plurality of wall portions and configured to detect the light of the first wavelength; a second light detection unit attached to a wall portion among the plurality of wall portions and configured to detect the light of the second wavelength; and a first temperature detection unit attached to a wall portion among the plurality of wall portions, the wall portion to which the first temperature detection unit is attached being different from the wall portion to which the first light detection unit is attached.