Infrared Thermal Imaging E-Book

Michael Vollmer

• Herausgeber: Wiley-VCH
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch
• Veröffentlichungsjahr: 2011

Seitenzahl: 895

Beschreibung

This richly illustrated hands-on guide is designed for researchers, teachers and practitioners. The huge selection of examples taken from science, basic teaching of physics, practical applications in industry and a variety of other disciplines spanning the range from medicine to volcano research allows readers to pick those that come closest to their own individual task at hand. Following a look at the fundamentals of IR thermal imaging, properties of the imaging systems, as well as basic and advanced methods, the book goes on to discuss IR imaging applications in teaching, research and industry. Specific examples include thermography of buildings, microsystems and the rather new field of IR imaging of gases. Impartially written by expert authors in the field from a renowned applied science institution, who are in the unique position of having both experience in public and private research and in teaching, this comprehensive book can be used for teaching beginners in the field as well as providing further education to specialized staff, students and researchers.

Leseprobe

Contents

Cover

Half Title page

Title page

Copyright page

Preface

Chapter 1: Fundamentals of Infrared Thermal Imaging

1.1 Introduction

1.2 Infrared Radiation

1.3 Radiometry and Thermal Radiation

1.4 Emissivity

1.5 Optical Material Properties in the IR

1.6 Thin Film Coatings: Tailoring Desired Optical Properties for IR Optical Components

References

Chapter 2: Basic Properties of IR Imaging Systems

2.1 Introduction

2.2 Detectors and Detector Systems

2.3 Basic Measurement Process

2.4 Complete Camera Systems

2.5 Camera Performance Characterization

References

Chapter 3: Advanced Methods in IR Imaging

3.1 Introduction

3.2 Spectrally Resolved Infrared Thermal Imaging

3.3 Superframing

3.4 Processing of IR Images

3.5 Active Thermal Imaging

References

Chapter 4: Some Basic Concepts of Heat Transfer

4.1 Introduction

4.2 The Basic Heat Transfer Modes: Conduction, Convection, and Radiation

4.3 Selected Examples for Heat Transfer Problems

4.4 Transient Effects: Heating and Cooling of Objects

4.5 Some Thoughts on the Validity of Newton’s Law

References

Chapter 5: Basic Applications for Teaching: Direct Visualizationof Physics Phenomena

5.1 Introduction

5.2 Mechanics: Transformation of Mechanical Energy into Heat

5.3 Thermal Physics Phenomena

5.4 Electromagnetism

5.5 Optics and Radiation Physics

References

Chapter 6: IR Imaging of Buildings and Infrastructure

6.1 Introduction

6.2 Some Standard Examples for Building Thermography

6.3 Geometrical Thermal Bridges versus Structural Problems

6.4 External Influences

6.5 Windows

6.6 Thermography and Blower-Door-Tests

6.7 Quantitative IR Imaging: Total Heat Transfer Through Building Envelope

6.8 Conclusions

References

Chapter 7: Industrial Application: Detection of Gases

7.1 Introduction

7.2 Spectra of Molecular Gases

7.3 Influences of Gases on IR Imaging: Absorption, Scattering, and Emission of Radiation

7.4 Absorption by Cold Gases: Quantitative Aspects

7.5 Thermal Emission from Hot Gases

7.6 Practical Applications: Gas Detection with Commercial IR Cameras

Appendix 7.A: Survey of Transmission Spectra of Various Gases

References

Chapter 8: Microsystems

8.1 Introduction

8.2 Special Requirements for Thermal Imaging

8.3 Microfluidic Systems

8.4 Microsensors

8.5 Microsystems with Electric to Thermal Energy Conversion

References

Chapter 9: Selected Topics in Research and Industry

9.1 Introduction

9.2 Thermal Reflections

9.3 Metal Industry

9.4 Automobile Industry

9.5 Airplane and Spacecraft Industry

9.6 Miscellaneous Industrial Applications

9.7 Electrical Applications

References

Chapter 10: Selected Applications in Other Fields

10.1 Medical Applications

10.2 Animals and Veterinary Applications

10.3 Sports

10.4 Arts: Music, Contemporary Dancing, Paintings, and Sculpture

10.5 Surveillance and Security: Range of IR Cameras

10.6 Nature

References

Index

Michael Vollmer and Klaus-Peter Möllmann

Infrared Thermal Imaging

Related Titles

Gross, H. (ed.)Handbook of Optical Systems6 Volume Set2011ISBN: 978-3-527-40382-0

Günzler, H. Gremlich, H.-U.IR Spectroscopy: An Introduction2002ISBN: 978-3-527-28896-0

Gerlach, G., Budzier, H.Thermische Infrarotsensoren2010ISBN: 978-3-527-40960-0

Schuster, N., Kolobrodov, V. G.Infrarotthermographie2004ISBN: 978-3-527-40509-1

Maldague, X. P. V.Theory and Practice of Infrared Technology for Nondestructive Testing2001ISBN: 978-0-471-18190-3

The Authors

Prof. Michael VollmerMicrosystem and Optical TechnologiesUniversity of Applied SciencesBrandenburg, [email protected]

Prof. Dr. Klaus-Peter MöllmannMicrosystem and Optical TechnologiesUniversity of Applied SciencesBrandenburg, [email protected]

Cover

Thermal pictures by Vollmer and Möllmann

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Print ISBN: 978-3-527-40717-0 ePdf ISBN: 978-3-527-63087-5 ePub ISBN: 978-3-527-64155-0 Mobi ISBN: 978-3-527-64055-3

Preface

The really large steps in the history of thermal imaging took place in intervals of hundred years. First, infrared radiation was discovered in 1800 by Sir William Herschel while studying radiation from the sun. Second, Max Planck was able to quantitatively describe the laws of thermal radiation in 1900. It took more than 50 years thereafter before the first infrared-detecting cameras were developed; initially, these were mostly quite bulky apparatus for military purposes. From about the 1970s, smaller portable systems started to become available; these consisted of liquid nitrogen cooled single photon detector scanning systems. These systems also enabled the use of infrared imaging for commercial and industrial applications. The enormous progress due to microsystem technologies toward the end of the 20th century—the first uncooled micro bolometer cameras appeared in the 1990s—resulted in reliable quantitatively measuring infrared camera systems. This means, that the third large step was taken by about the year 2000. Infrared thermal imaging has now become affordable to a wider public of specialized physicists, technicians and engineers for an ever growing range of applications. Nowadays, mass production of infrared detector arrays leads to comparatively low price cameras which—according to some advertisements—may even become high-end consumer products for everyone.

This rapid technological development leads to the paradoxical situation that there are probably more cameras sold worldwide than there are people who understand the physics behind and who know how to interpret the nice and colorful images of the false color displays: IR cameras easily produce images, but unfortunately, it is sometimes very difficult even for the specialist to quantitatively describe several of the most simple experiments and/or observations.

The present book wants to mitigate this problem by providing an extensive background knowledge on many different aspects of infrared thermal imaging for many different users of IR cameras. We aim at least for three different groups of potential users.

First, this book addresses all technicians and engineers who use IR cameras for their daily work. On the one hand, it will provide extensive and detailed background information not only on detectors and optics but also on practical use of camera systems. On the other hand, a huge variety of different application fields is presented with many typical examples with hints of how to notice and deal with respective measurement problems.

Second, all physics and science teachers at school or university level can benefit since infrared thermal imaging is an excellent tool for visualization of all phenomena in physics and chemistry related to energy transfer. These readers can particularly benefit from the huge variety of different examples presented from many fields, a lot of them given with qualitative and/or quantitative explanations of the underlying physics.

Third, this text also provides a detailed introduction to the whole field of infrared thermal imaging from basics via applications to up to date research. Thus it can serve as a textbook for newcomers or as a reference handbook for specialists who want to dig deeper. The large number of references to original work can easily help to study certain aspects in more depth and thus get ideas for future research projects.

Obviously, this threefold approach concerning the addressed readers does have some consequences for the structure of the book. We tried to write the ten chapters such that each may be read separately from the others. In order to improve the respective readability, there will be some repetitions and also cross references in each chapter (that more information can be found in other chapters or sections).

For example, teachers or practitioners may initially well skip the introductory more theoretical chapters about detectors or detectors systems and jump right away into the section of their desired applications. Obviously, this sometimes means that not every detail of explanation referring to theory will be understood, but the basic ideas should become clear—and maybe later on, those readers will also get interested in checking topics in the basic introductory sections.

The organization of this book is as follows: the first three chapters will provide extensive background information on radiation physics, single detectors as well as detector arrays, camera systems with optics, and IR image analysis. This is followed by a partly theoretical chapter on the three different heat transfer modes, which will help enable a better understanding of the temperature distribution that can be detected at the surfaces of various objects as e.g., buildings. Chapter 5 then gives a collection of many different experiments concerning phenomena in physics. This chapter was particularly written with teaching applications in mind. The subsequent three chapters discuss three selected application as well as research topics in more detail: building thermography as a very prominent everyday application, the detection of gases as a rather new emerging industrial application with very good future prospects and the analysis of microsystems for research purposes. Finally, the last two chapters give a large number of other examples and discussions of important applications ranging for example from the car industry, sports, electrical, and medical applications via surveillance issues to volcanology.

Our own background is twofold. One of us had originally worked in IR detector design before switching to microsystem technologies whereas the other worked on optics and spectroscopy. Soon after joining our present affiliation, a fruitful collaboration in a common new field, IR imaging, developed, starting with the purchase of our first MW camera in 1996. Meanwhile, our infrared group has access to three different IR camera systems from the extended MW to the LW range including a high speed research camera and a lot of additional equipment such as microscope lenses and so on. Besides applied research, our group focuses also on teaching the basics of IR imaging to students of Microsystem and Optical Technologies at our university.

Obviously, such a book cannot be written without the help of many people, be it by discussions, by providing images, or just by supporting and encouraging us in phases of extreme work load towards the end of this endeavor. We are therefore happy to thank in particular our colleagues Frank Pinno, Detlef Karstädt, and Simone Wolf for help with various tasks that had often to be done at very short notice.

Furthermore, we want to especially thank Bernd Schönbach, Kamayni Agarwal, Gary Orlove, and Robert Madding for fruitful discussions on selected topics and also for permission to use quite a large number of IR images.

We are also grateful to S. Calvari, J. Giesicke, M. Goff, P. Hopkins, A. Mostovoj, M. Ono, M. Ralph, A. Richards, H. Schweiger, D. Sims, S. Simser C. Tanner, and G. Walford for providing IR images and to A. Krabbe & D. Angerhausen, as well as DLR for providing other graphs. Also the following businesses have given permission to reproduce images, which we gratefully acknowledge: Alberta Sustainable Resource development, BMW, Daimler, FLIR systems, IPCC, IRIS, ITC, MoviTHERM, NAISS, NASA, Nature, NRC of Canada, PVflex, Raytek, Telops, Ulis, as well as United Infrared Inc.

Finally we need to especially thank our families for their tolerance and patience, in particular during the final months. Last not least we also need to express special thanks for the effective working together with Mrs. Ulrike Werner from Wiley/VCH.

Chapter 1

Fundamentals of Infrared Thermal Imaging

1.1 Introduction

Infrared (IR) thermal imaging, also often briefly called thermography, is a very rapidly evolving field in science as well as industry owing to the enormous progress made in the last two decades in microsystem technologies of IR detector design, electronics, and computer science. Thermography nowadays is applied in research and development as well as in a variety of different fields in industry such as nondestructive testing, condition monitoring, and predictive maintenance, reducing energy costs of processes and buildings, detection of gaseous species, and many more. In addition, competition in the profitable industry segment of camera manufacturers has recently led to the introduction of low-cost models of the order of just several thousands dollars or euros, which opened up new fields of uses. Besides education (obviously schools are notorious for having problems with financing expensive equipment for science classes), IR cameras will probably soon be advertised in hardware stores as “must have” products for analyzing building insulation, heating pipes, or electrical components of one’s own home. This development has its advantages as well as drawbacks.

The advantages may be illustrated by an anecdote based on personal experiences concerning physics teaching in school. Physics was, and still is, considered to be a very difficult subject in school. One of the reasons may be that simple phenomena of physics, for example, friction or the principle of energy conservation in mechanics, are often taught in such an abstract way that rather than being attracted to the subject, students are scared away. One of us clearly remembers a frustrating physics lesson at school dealing first with free-falling objects and next, with the action of walking on a floor. First, the teacher argued that a falling stone would transfer energy to the floor such that the total energy was conserved. He only used mathematical equations but stopped his argument at the conversion of initial potential energy of the stone to kinetic energy just prior to the impact with the floor. The rest was a hand-waving argument that, of course, the energy would be transformed to heat. The last argument was not logically developed it was just one of the typical teacher arguments to be believed (or not). Of course, at those times, it was very difficult at schools to actually measure the conversion of kinetic energy into heat. Maybe the children would have been more satisfied if he had at least attempted to visualize the process in more detail. The second example – explaining the simple action of walking – was similarly frustrating. The teacher argued that movement was possible owing to the frictional forces between shoe and floor. He then wrote down some equations describing the physics behind and that was all. Again, there were missing arguments: if someone walking has to do work against frictional forces, there must be some conversion of kinetic energy into heat and shoes as well as the floor must heat up. Again, of course, at those times, it was very difficult at schools to actually measure the resulting tiny temperature rises of shoes and floor. Nevertheless not discussing them at all was a good example of bad teaching. And again, maybe some kind of visualization would have helped. But visualizations were not one of the strengths of this old teacher who rather preferred to have Newton’s laws recited in Latin.

Visualization is any technique for creating images, diagrams, or animations to communicate an abstract or a concrete argument. It can help bring structure into a complex context, it can make verbal statements clear, and/or give clear and appropriate visual representations of situations or processes. The underlying idea is to provide optical conceptions that help to better understand and better recollect the context. Today, in the computer age, visualization has ever-expanding applications in science, engineering, medicine, and so on. In the natural sciences, visualization techniques are often used to represent data from simulations or experiments in plots or images in order to make analysis of the data as easy as possible. Strong software techniques often enable the user to modify the visualization in real time, thus allowing easy perception of patterns and relations in the abstract data in question.

Thermography is an excellent example of a visualization technique that can be used in many different fields of physics and science. Moreover, it has opened up a totally new realm of physics in terms of visualization. Nowadays, it is possible to visualize easily the (for human eyes) invisible effects of temperature rise of the floor upon impact of a falling object or upon interaction with the shoe of a walking person. This will allow totally new ways of teaching physics and the natural sciences starting in school, and ending in the training of professionals in all kinds of industries. Visualization of “invisible” processes of physics and/or chemistry with thermography can be a major factor creating fascination for and interest in these subjects, not only in students at school and university but also for the layman. Nearly every example described later in this book can be studied in this context.

The drawbacks of promoting IR cameras as mass products for a wide range of consumers are less obvious. Anyone owning an IR camera will be able to produce nice and colorful images, but most will never be able to fully exploit the potentials of such a camera – and most will never be able to correctly use it.

Typically, the first images recorded with any camera will be the faces of people around. Figure 1.1 gives an example of IR images of the two authors. Anyone, confronted with such images for the first time, would normally find them fascinating since they provide a totally new way of looking at people. The faces can still be recognized, but some parts look strange, for example, the eyes. Also, the nostrils (Figure 1.1b) seem to be distinctive and the hair seems to be surrounded by an “aura.”

Figure 1.1 IR thermal images of (a) K-P. Möllmann and (b) M. Vollmer.

For artists, who want to create new effects, such images are fine, but thermography – if it is to be used for analysis of real problems like building insulation, and so on – is much more than this. Modern IR cameras may give qualitative images, colorful images that look nice but mean nothing, or they can be used as quantitative measuring instruments. The latter use is the original reason for developing these systems. Thermography is a measurement technique, which, in most cases, is able to quantitatively measure surface temperatures of objects. In order to use this technique correctly, professionals must know exactly what the camera does and what they can do to extract useful information from such IR images. This knowledge can only be gathered by professional training. Therefore, the drawback when purchasing an IR camera is that everybody needs professional training before one can correctly use such a camera. A multitude of factors can have an influence on the IR images and, hence, on any interpretation of such images (see and Chapters 2, 6,).