Radiation thermometry: The measurement problem

Classic article by G. D. (Gene) Nutter from a NASA ARCHIVE et.al.

ASTM STP895 Cover
ASTM STP895 Cover (Image credit ASTM International)

This online article is very similar and covers most of the same materials as  “Radiation Thermometry — The Measurement Problem” delivered at a symposium sponsored by ASTM Committee E-20 on Temperature Measurement in cooperation with the National Bureau of Standards, Gaithersburg, MD on May 8, 1984.

This was subsequently published as the first chapter in the volume “Applications of Radiation Thermometry”, ASTM SPECIAL TECHNICAL PUBLICATION 895, J.C. Richmond, National Bureau of Standards and D.P. DeWitt, editors.

 

Radiation Thermometry—The Measurement Problem
Symposium Paper

January 1985 — STP895  STP38703S
The basic measurement problems of radiation thermometry are discussed, with emphasis on the physical processes giving rise to the emissivity effects observed in real materials. Emissivity is shown to derive from bulk absorptivity properties of the material. Blackbody radiation is produced within an opaque isothermal material, with partial internal reflection occurring at the surface.

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Gene Nutter wrote this and many other  technical articles on the subject of radiation thermometry, including another classic , “A High Precision Automatic Optical Pyrometer in Temperatures ITS measurement and Control in Science and Industry, Vol. 4, 519-530, Instrument Society of America (1972).

Description: “An overview of the theory and techniques of radiometric thermometry is presented. The characteristics of thermal radiators (targets) are discussed along with surface roughness and oxidation effects, fresnel reflection and subsurface effects in dielectrics.

“The effects of the optical medium between the radiating target and the radiation thermometer are characterized including atmospheric effects, ambient temperature and dust environment effects and the influence of measurement windows.

“The optical and photodetection components of radiation thermometers are described and techniques for the correction of emissivity effects are addressed.”

NASA Info:Link to article: https://archive.org/details/NASA_NTRS_Archive_19880014512

Publication date 1988-03-01
Topics NASA Technical Reports Server (NTRS), INFRARED RADIOMETERS, RADIATION PYROMETERS, TEMPERATURE MEASUREMENT, THERMOMETERS, BLACK BODY RADIATION, RADIANCE, SPACE COMMERCIALIZATION, SURFACE ROUGHNESS, THERMAL EMISSION, Nutter, G. D.,
Collection NASA_NTRS_Archive; additional_collections
Language English
Identifier NASA_NTRS_Archive_19880014512
Identifier-ark ark:/13960/t9h46mr2v
Ocr ABBYY FineReader 11.0
Pages 61

Ed Note (from the book jacket of the 1988 book “Theory and Practice of Radiation Thermometry”,  Edited by D.P. Dewitt and Gene D. Nutter, John Wiley & Sons, Inc.): “Gene D. Nutter is (was)  a senior staff member of the Instrumentation Center, College of Engineering, University of Wisconsin-Madison. He received his MS in Physics from  University of Nebraska and had been earlier associated with the National Bureau of Standards and Atomics International.”

Chapter 5 in the above referenced text is linked below below. a classic book on the theory & practices of radiation thermometry published in 1998. It was recently found on Amazon.com and ebay.com at the following links:

https://www.amazon.com/dp/0471610186/ref=rdr_ext_tmb FOR ABOUT $349.

AND for between $353 and $453 on ebay at:  https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313.TR0.TRC0.H0.Xtheory+%26+practice+of+radiation+thermometry.TRS0&_nkw=theory+%26+practice+of+radiation+thermometry&_sacat=0

 

Glossaries

There are many specialized glossaries that cover the terms describing the unique details about temperature and moisture sensors and their uses and this page represents an attempt to index most of them in one place.

CONTACT TEMPERATURE SENSORS:

Thermistors: https://www.temperatures.com/blog/2018/04/04/thermistor-gloss…-and-terminology/.

Thermocouples:

RTDS: 

 

NONCONTACT TEMPERATURE SENSORS:

Many online articles about radiation thermometry and its uses (infrared thermometers, radiation pyrometers) exist including technology articles, PowerPoint slide presentations and .pdf downloads, but they seem to be vanishing as more and more “big businesses” take over these specialized sensors.But few are aimed at being useful glossaries or definition of terms.

There are some exceptions and some well-crafted pieces that have been online for a while and can be found in semi-hidden corners of the Web.

Thermal Radiation Thermometers: temperature_measurement_radiation_thermometers

Thermal Imaging:  (Glossary of Basic Thermography Terms) http://www.ne-spintech.com/Glossary%20of%20Basic%20Thermography%20Terms.pdf .

Clearly this is a work in progress, and it may be expanded in time. Priority will be according to the response it garners.

 

Understanding Radiation Thermometry Parts I & II

From NASA Technical Reports Server (NTRS)

From NASA Article
From NASA Article

In 2015, Timothy K. Risch of NASA developed two technical articles that are available on the NASA Technical Reports Server (NTRS).

Both articles may be freely downloaded from NTRS in various formats, as long as the NASA Server maintains their presence.

As far as we know these are royalty free and the only stipulation that NASA usually requires is an attribution. These are below in the form of links to the article on the NASA web site.

The articles are entitled:

Understanding Radiation Thermometry. Part I, 71 pages, publication date 2015-07-08, and Understanding Radiation Thermometry. Part II, 111 pages, same publication date.

We have reviewed these documents and find them to be an excellent summary of this temperature measurement method and have archived them on our site in two formats, mobi, suitable for reading on an E-reader and in Adobe pdf format.

Part 1 provides and Overview, Nomenclature, a bit about what temperature is and the history of measurement methods and delves into the physics underlying Radiation Thermometry.

Part II covers practical radiation thermometers, some detail on measurement techniques and calibration and a brief reference list.

These files are linked below many be freely downloaded as long as we maintain this website.

The NASA description for both article reads as follows:

This document is a two-part course on the theory and practice of radiation thermometry.

Radiation thermometry is the technique for determining the temperature of a surface or a volume by measuring the electromagnetic radiation it emits.

This course covers the theory and practice of radiative thermometry and emphasizes the modern application of the field using commercially available electronic detectors and optical components.

The course covers the historical development of the field, the fundamental physics of radiative surfaces, along with modern measurement methods and equipment.
NASA Technical Reports Server (NTRS) 20150021314 Understanding Radiation Thermometry. Part I NASA Technical Reports Server (NTRS) Free Download & Streaming Internet Archive

Understanding Radiation Thermometry – Part I pdf Format Timothy K. Risch NASA Armstrong Flight Research Center July 8, 2015

NASA Technical Reports Server (NTRS) 20150021315 Understanding Radiation Thermometry. Part II NASA Technical Reports Server (NTRS) Free Download & Streaming Internet Archive

Understanding Radiation Thermometry – Part II pdf Format Timothy K. Risch NASA Armstrong Flight Research Center July 8, 2015

Sources on the NASA Technical Reports Server:

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20150021314.pdf

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20150021315.pdf

The Use of Johnson’s Criteria for Thermal Infrared Camera & Systems Performance

Written by: Opgal staff writers  (August 03, 2017)

OPGAL Blog LinkOnline —  When customers are considering which thermal security camera or system to buy, one of the first questions asked of thermal imager manufacturers is usually: “At what distance can the IR camera detect a target?.

In other words, what is the camera’s ability to capture very small details at great distances?

When thinking about effective surveillance, it is indeed a good criterion to differentiate one sensor from another.

No matter which manufacturer you are buying from, the answer given to this question will almost always include the DRI ranges expression.

DRI refers to the distance at which a target can be Detected, Recognized, or Identified, based on certain universally accepted parameters.

In order to select the right sensor for your defense, security, or surveillance needs, these DRI ranges have to be, first, perfectly defined, but also assessed with regards to globally adopted industrial standards.

Enter: The Origin of Johnson’s Criteria

In 1958, at the first ever “Night Vision Image Intensifier Symposium”, John Johnson, a night vision scientist at the U.S. Army’s “Night Vision and Electronic Sensors Directorate” (NVESD), presented a paper named the Analysis of Image Forming Systems”.

Johnson’s paper defined a clear system with criteria and methodology for predicting an observer’s ability to find and assess targets using image intensifying equipment (such as thermal cameras), under various conditions. It worked well, and it was the first of its kind.

Johnson’s Criteria Definitions

Johnson’s model provided definitive criteria for calculating the maximum range at which “Detection, Recognition, and Identification (D, R, I)” could take place, with a 50% probability of success. (Orientation was also discussed, but this parameter is not used or recognized today).

Although newer methodologies for D,R,I exist today, such as NVESD’s “Night Vision Image Performance Model” (NV-IPM), the “Johnson’s Criteria” system was groundbreaking for its time, was the accepted standard in the defense industry for many years, and is still widely used in the security industry today.

Detection

Johnson defined “Detection” as the ability to subtend 1 TV line pair (+/- 0.25 line pairs) across the critical dimension of the subject (this translates to 2 pixels when using an LCD monitor). At the range that this occurs, regardless of target type, the observer could detect that a subject was in the field of view, 50% of the time. Today, many security camera companies loosely follow Johnson’s Criteria and define their camera’s “Detection” performance range as the ability to subtend either 1.5 or 2 pixels on the target, using various target sizes.

Recognition

Johnson defined “Recognition” as the ability to subtend 4 TV line pairs (+/- 0.8 line pairs) across the critical dimension of the subject (this translates to 8 +/- 1 pixels when using an LCD monitor). At the range that this occurs, regardless of target type, the observer determines the type of subject, a human or a car for example, 50% of the time. Today many security camera companies typically define their cameras “Recognition” performance range as the ability to subtend 6 pixels on the target, using various target sizes.

Identification

Johnson defined “Identification” as the ability to subtend 6.4 TV line pairs (+/- 1.5 line pairs) across the critical dimension of the subject (this translates to 12 +/- 3 pixels when using an LCD monitor). At the range that this occurs, regardless of target type, the observer could detect the subject.

Today many security camera companies loosely follow Johnson’s Criteria and define their cameras “Identification” performance range as the ability to subtend 12 pixels on the target, using various target sizes.

Long range performance

Johnson’s Criteria in the Security Industry

DRI ranges, expressed in kilometers (or miles), can usually be found in the specification table of infrared camera brochures, or in a description of the cameras features. While a very helpful jumping off point for narrowing down the options and homing in on the best systems, customers would be doing themselves a disservice to only look at DRI.

This is because today the application of Johnson’s criteria varies somewhat across the security industry. In most instances, documentation uses simplified or modified versions of the criteria, but they do all generally follow similar rules.

Typically, most companies use twelve pixels on the target for identification, six for recognition, and two for detection (sometimes 1.5). However, the target size can vary greatly. Normally the defense industry “NATO” target size (2.3×2.3 meters) is used for calculating the performance range for detecting vehicles, but for a human target, various target sizes can be found.

It is important when selecting your thermal infrared camera to keep in mind that in any given document, the target size for a human can range from 1.7-1.83 meters tall and from 0.3- 0.75 meters wide, and factor this into your decision-making process.

The Need to look at the Bigger Picture

Because end-users often place a high value on the written specifications of the camera, marketing departments are under pressure to use performance calculations that make their cameras look better than the competitors. However, since these calculations typically do not take environmental factors into account, customers should ask their thermal camera providers to explain the other elements and benefits of each camera they are offering, and how they will perform in a variety of conditions.

A modified approach that considers parameters such as these can better help in choosing the right or system for your needs.

The post appeared first on OPGAL.com.

Using Thermal Infrared in “Furnace and Heater Tube Inspections”

by Ron Lucier, ASNT NDT Level III

(From the IRInformIR.blogspot.com, September 27, 2017 with format altered for easier reading online – all text and images from IRInformIR)

ITC logo registered“One of the more challenging applications of infrared thermography is in the measurement of process heater and furnace tubes. In fact we get dozens of inquiries each year from our clients on this very subject.

“Since this is a very complex subject it is probably appropriate to start from the beginning.”

“Process Heaters”
There are as many uses for process heaters as there are designs. The basic configuration consists of a shell (outer casing), tubes (where the process fluid flows) and a heat source.

“These units are both thermodynamically and hydraulically complex.”

Process heater or furnace diagram

“In the simple drawing above we illustrate convective gas flow, which is turbulent, and radiant heat from the flame, refractory and other tubes – all non-uniform and time varying. When you view tube from an access port typically you can only see a portion of the tube or the tube at an oblique angle.

“Therefore, the odds are stacked against you from the start!”

“Why are heater tubes of interest anyway?”
Heater tubes 1“There are several reasons for inspecting tubes. Qualitatively slag (scale) buildup on the outside of the tube can be readily identified.

“Buildup on the inside of the tube (coking) is a bit more difficult but commonly performed.

“In both cases the slag or coke prevents the transfer of heat into the process fluid. In the case of slag buildup, the process fluid may not be sufficiently heated, affecting downstream processing.

“The case of coking on the inside of the tube is more serious. Since the coke has an increased resistance to heat transfer, the tube surface temperature increases.

“After all it is the flow of the process fluid that is keeping the tube “cool” in the first place.

“In fossil boilers this is called “DNB” – Departure from Nucleate Boiling and is usually caused by flame impingement, which initiates a layer of steam on the inside of the tube. The external tube surface, unable to conduct its heat to the water, increases dramatically, causing a failure (opening) in the tube.”

Read more »

ED NOTE: The SPIE has published a very useful and detailed book in its Tutorial Text Series entitled
Radiation Thermometry: Fundamentals and Applications in the Petrochemical Industry
Author(s): Peter Saunders (August 2007) that deals with this topic in depth from the point of view of non-contact temperature measurement (radiation thermometry). It contains a wealth of detail about the issues of slag and reflected thermal radiation as well as a useful tutorial on infrared temperature measurement.

It is available online at the SPIE bookstore at a modest price as both a softcover book and a pdf download.

The link is: https://spie.org/Publications/Book/741687.

Here’s some details from the (above) linked SPIE web page:

Book Description

This tutorial text provides an introduction to the subject of radiation thermometry, focusing on sources of measurement error and giving advice on methods for minimizing or eliminating these errors. Topics covered include: blackbody radiation, emissivity, reflection errors, and atmospheric absorption and emission; commonly used radiation thermometer types; uncertainty calculation; and procedures for in-house calibration of radiation thermometers. Included is a chapter containing detailed measurement examples for a variety of furnace types and operating conditions found in the methanol, ammonia, and refining industries.

Book Details
Date Published: 3 August 2007
Pages: 176
ISBN: 9780819467836
Volume: TT78

Industrial temperature measurement | Basics and practice

Free Download From ABB

(Extract From the Introduction)

With this Handbook for industrial temperature measurements we are attempting to provide the technician with solutions to his wide variety of responsibilities. At the same time, it provides for those new to the field, insight into the basics of the most important measurement principles and their application limits in a clear and descriptive manner.

The basic themes include material science and measurement technology, applications, signal processing and fieldbus communication.

A practice oriented selection of appropriate temperature sensor designs for the process field is presented as well as therequired communication capability of the meter locations.

The factory at Alzenau, Germany, a part of ABB, is the Global Center of Competencefor Temperature, with numerous local experts on hand in the most important industrialsectors, is responsible for activities worldwide in this sector.

125 years of temperature measurement technology equates to experience and competence. At the same time, it forms an important basis for continued innovation.

In close cooperation with our customers and users, our application engineers create conceptsto meet the measurement requirements.

Our Sector-Teams support the customer, planner and user in the preparation of professional solutions.

Free download available online at: https://library.e.abb.com/public/6bfb8fc893ac4d0da0a806ce8cd73996/03_TEMP_EN_E.pdf

Author Team:
Karl Ehinger, Dieter Flach, Lothar Gellrich, Eberhard Horlebein, Dr. Ralf Huck, Henning Ilgner, Thomas Kayser, Harald Müller, Helga Schädlich, Andreas Schüssler, Ulrich Staab,

ABB Automation Products GmbH

Many thanks to the publishing group at ControlEngineering-Europe for alerting us to this new online resource (http://www.controlengeurope.com/article/140944/Handbook-aims-to-simplify-industrial-temperature-measurement.aspx)

National Physical Laboratory Video Presentations on Temperature Measurements

 

New references for high temperature measurements

As a culmination of an eight-year research programme an international collaboration has developed robust reference fixed points, studied their sensitivity to impurities and external conditions and finally measured their melting transition temperature.

This talk describes how 100+ measurements made by nine different NMIs have been combined to assign low-uncertainty thermodynamic temperatures to the melting transition of Re-C, Pt-C and Co-C metal-carbon eutectics.

At the simplest level, these fixed-points will provide new temperature references for the calibration of pyrometers at temperatures above the freezing point of silver (1234.93 K) and will thus reduce the uncertainties associated with high temperature measurement compared to those achievable using the International Temperature Scale of 1990 (ITS-90).

The thermodynamic temperatures of these fixed-points have been determined through direct measurement of the radiance of a blackbody cavity surrounded by the fixed-point material from Planck’s law and hence the Boltzmann Constant. The evolving mise en pratique for the definition of the kelvin encourages the realisation and dissemination of thermodynamic temperature.

This may be directly – and the work described in this talk shows that filter radiometry is sufficiently mature for this, or it may be by providing fixed-points with reference thermodynamic temperatures that have associated uncertainties – and this talk will outline such temperatures.
Innovations in High Temperature Measurement

A 49 minute review of the present technical status of High Temperature measurement by one of the leaders in temperature Metrology at NPL in the UK.

Presented by Dr. Graham Machin, NPL (Recorded July 2011)

Recent and unfolding innovations in this area promise step change improvements throughout the measurement chain; from realisation of temperature above 1300 K in National Measurement Institutes, dissemination of the scale to calibration laboratories, down to the practice of industrial high temperature thermometry.

Source: http://www.npl.co.uk/science-lectures/high-temperature-measurement

More details: Read more National Physical Laboratory Video Presentations on Temperature Measurements

New references for high temperature measurements

Summary of work reported for high temperature measurements from NPL

As a culmination of an eight-year research programme an international collaboration has developed robust reference fixed points, studied their sensitivity to impurities and external conditions and finally measured their melting transition temperature.

This talk describes how 100+ measurements made by nine different NMIs have been combined to assign low-uncertainty thermodynamic temperatures to the melting transition of Re-C, Pt-C and Co-C metal-carbon eutectics.

At the simplest level, these fixed-points will provide new temperature references for the calibration of pyrometers at temperatures above the freezing point of silver (1234.93 K) and will thus reduce the uncertainties associated with high temperature measurement compared to those achievable using the International Temperature Scale of 1990 (ITS-90).

The thermodynamic temperatures of these fixed-points have been determined through direct measurement of the radiance of a blackbody cavity surrounded by the fixed-point material from Planck’s law and hence the Boltzmann Constant.

The evolving mise en pratique for the definition of the kelvin encourages the realisation and dissemination of thermodynamic temperature.

This may be directly – and the work described in this talk shows that filter radiometry is sufficiently mature for this, or it may be by providing fixed-points with reference thermodynamic temperatures that have associated uncertainties – and this talk outlines such temperatures.

Recorded: 16 June 2015

Speaker: Emma Woolliams

Last Updated: 10 Sep 2015

Source: http://www.npl.co.uk/science-lectures/new-references-for-high-temperature-measurements

YouTube Video: https://www.youtube.com/watch?v=l4Ws6PiqQ9cs.YouTube video:

Further information

Related areas

TI Temperature Measurement Videos

TI, or Texas Instruments, is one of the world’s most prolific and largest makers of temperature sensors. They make all kinds but their sensors are mostly in the form of Integrated Circuit semiconductors.

TI also does an exceptional job in educating users how their devices work and how they can be interfaced and incorporated in measurement systems. Especially useful are the videos showing how some of their other integrated circuit modules can be used with external temperature sensors, like Thermocouples, RTDs and Thermistors.

Here’s an example of an interesting one:

Developed through TI’s expertise in MEMS technology, the TMP006 is the first of a new class of ultra-small, low power, and low cost passive infrared temperature sensors. It has 90% lower power consumption and is more than 95% smaller than existing solutions, making contactless temperature measurement possible in completely new markets and applications.

Check out their Video Channel on YouTube, especially the long list of videos already published about “Temperature Measurement”. It very straightforward; just go to: https://www.youtube.com/user/texasinstruments/search?query=%22temperature+measurement%22

Acoustic Gas Thermometry Review Article

Metrologia Cover Image
Metrologia Cover Image

Online  —  Acoustic gas thermometry (AGT) is not a very well known temperature measurement technique; several have been reported in the past.

This featured review article in Metrologia (Acoustic gas thermometry M R Moldover et al 2014 Metrologia 51 R1) by six authors from six different  NMIs around the world provides a modern update on the technology and its significance in helping determine values of physical reference temperatures points on the International Temperature Scale of 1990 (ITS-90).

Acoustic Gas Thermometry

Authors: M R Moldover1, R M Gavioso2, J B Mehl3, L Pitre4, M de Podesta5 and J T Zhang6

Review Article ABSTRACT

We review the principles, techniques and results from primary acoustic gas thermometry (AGT). Since the establishment of ITS-90, the International Temperature Scale of 1990, spherical and quasi-spherical cavity resonators have been used to realize primary AGT in the temperature range 7 K to 552 K. Throughout the sub-range 90 K < T < 384 K, at least two laboratories measured (T − T90). (Here T is the thermodynamic temperature and T90 is the temperature on ITS-90.) With a minor exception, the resulting values of (T − T90) are mutually consistent within 3 × 10−6 T. These consistent measurements were obtained using helium and argon as thermometric gases inside cavities that had radii ranging from 40 mm to 90 mm and that had walls made of copper or aluminium or stainless steel. The AGT values of (T − T90) fall on a smooth curve that is outside ±u(T90), the estimated uncertainty of T90. Thus, the AGT results imply that ITS-90 has errors that could be reduced in a future temperature scale. Recently developed techniques imply that low-uncertainty AGT can be realized at temperatures up to 1350 K or higher and also at temperatures in the liquid-helium range.

The complete article can be obtained online at: http://iopscience.iop.org/0026-1394/51/1/R1/article.

About Metrologia

It is the leading international journal in pure and applied metrology, published by IOP Publishing on behalf of Bureau International des Poids et Mesures (BIPM), the International Bureau of Weights and Measures. It is published by the Institute of Physics (IOP) in The United Kingdom.

Online at: http://iopscience.iop.org/0026-1394
—————————

1 Sensor Science Division, National Institute of Standards and Technology, Gaithersburg, MD, USA
2 Thermodynamics Division, Istituto Nazionale di Ricerca Metrologica, 10135 Turin, Italy
3 36 Zunuqua Trail, PO Box 307, Orcas, WA 98280-0307, USA
4 Laboratoire Commun de Métrologie LNE-Cnam (LCM), 61 rue du Landy, 93210 La Plaine Saint-Denis, France
5 National Physical Laboratory, Teddington, Middlesex, TW11 0LW, UK
6 National Institute of Metrology, Beijing 100013, People’s Republic of China