Thin-Film Thermal Reference Source for Optical Sensor Calibration

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Solution Overview

Problem

Traditional blackbody sources used for calibrating optical sensors are bulky, heavy, and power-intensive, and temperature sensors disrupt the uniformity of the radiative surface in thin-film devices, making it challenging to achieve accurate temperature measurements for calibration.

Innovation Solution

A thin-film device with a first carbon nanotube layer generating heat in response to applied voltage, a second carbon nanotube layer producing a blackbody radiation spectrum, and a thermocouple between the layers to measure temperature without affecting the temperature uniformity, using a thermal spreading layer to ensure even heat distribution across the radiative surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional blackbody sources are used for calibration, then accurate temperature measurement is achieved, but size, weight, and power requirements increase significantly

Engineering Contradiction:
Improvetemperature measurement accuracyVSAvoiddevice weight
Core Design Contradiction:
Measurement precisionVSWeight of moving object

Solution Approach 1:

The patent employs thin-film carbon nanotube layers as the radiative surface, replacing traditional bulky blackbody sources. The thin-film structure dramatically reduces device weight and size while maintaining the blackbody radiation characteristics necessary for accurate optical sensor calibration.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The invention uses composite material structures including carbon nanotube layers combined with thermocouple materials and substrate materials. This composite approach enables both the blackbody radiation function and temperature measurement function within a compact, lightweight integrated device.

Inventive Principle:
Principle #40Composite materials

2Measurement precision

If temperature sensors are placed on the radiative surface, then temperature measurement is enabled, but temperature uniformity across the surface is disrupted

Engineering Contradiction:
Improvetemperature measurement capabilityVSAvoidtemperature uniformity
Core Design Contradiction:
Measurement precisionVSTemperature

Solution Approach 1:

The patent introduces a thermal spreading layer as an intermediary between the heat source and the radiative surface. This layer distributes heat uniformly across the carbon nanotube radiative surface, preventing localized temperature variations that would be caused by direct sensor contact or localized heating.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention implements different functional layers with specialized properties: the carbon nanotube layer provides high-emissivity radiation, the thermal spreading layer ensures uniform heat distribution, and the thermocouple layer enables temperature measurement. Each layer is optimized for its specific function while working together to maintain overall temperature uniformity.

Inventive Principle:
Principle #3Local quality

3Weight of moving object

If thin-film devices are used to reduce size, then SWaP challenges are addressed, but temperature measurement becomes more difficult due to thermal mass and conductivity effects

Engineering Contradiction:
Improvedevice size and weightVSAvoidtemperature measurement difficulty
Core Design Contradiction:
Weight of moving objectVSDifficulty of detecting and measuring

Solution Approach 1:

The patent replaces traditional mechanical temperature sensing methods with thermocouple-based measurement. The thermocouples are integrated directly into the thin-film structure, eliminating the need for separate mechanical sensor assemblies and their associated mounting hardware, thereby maintaining the compact form factor while enabling accurate temperature measurement.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 allows for precise temperature control and uniformity across the radiative surface, enabling accurate calibration of optical sensors while minimizing the size, weight, and power requirements, and maintaining the temperature uniformity necessary for effective calibration.

Implementation Method 1

a first carbon nanotube layer configured to generate heat in response to an applied voltage

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

a second carbon nanotube layer configured to generate the blackbody radiation spectrum in response to the heat from the first carbon nanotube layer

Methodology Applied
Scientific EffectBlackbody radiation: Thermal Radiation

Implementation Method 3

a thermocouple between the first carbon nanotube layer and the second carbon nanotube layer for measuring a temperature at the second carbon nanotube layer

Methodology Applied
Scientific EffectSeebeck effect: Seebeck Effect

Data Source

PatentEP3362769B1Thin film based thermal reference source
Publication Date: 2020.02.19 RAYTHEON CO
  • EP3362769B1 patent drawingFigure 1
  • EP3362769B1 patent drawingFigure 2
  • EP3362769B1 patent drawingFigure 3~5

AI summary

A thin-film device for generating a blackbody spectrum is disclosed. The device includes first layer configured to generate heat in response to an applied voltage and a second layer configured to generate the blackbody radiation spectrum in response to the heat from the first layer. A thermocouple is disposed between the first layer and the second layer for measuring a temperature at the second layer. The thermocouple measures temperature at the second layer in order to control temperature at the second layer. The thermocouple can be a copper-carbon nanotube thermocouple.