Abstract: The present invention relates to a method of measuring the thickness of a thin film layer using an infrared thermal imaging system. The object of the present invention is to provide a method of measuring the thickness of a thin film layer fast in such a way as to obtain the two-dimensional (2-D) thickness distribution of the thin film layer at one time by measuring infrared spontaneous light emitted from a target surface using an infrared imaging camera.

Abstract: A portable thermal imaging analysis for analyzing a specimen includes a frame removably attachable to the specimen by a vacuum and suction cups. The apparatus also includes a sound source and thermal imaging camera that generates thermal images of the specimen along with a controller connected to the sound source and the imaging camera.

Abstract: A hand-held sound source for use in an infrared or thermal imaging system that detects sub-surface defects in a structure. The sound source includes a transducer that is positioned against the structure to emit a sound signal into the structure. The sound source further includes an adjustable spring that pushes the transducer against the structure with a predetermined amount of force so that the sound energy is effectively coupled into the structure. The sound source also includes three stabilizing legs that stabilize the transducer on the structure. The length of each leg can be adjustable relative to the length of the other legs so that the sound source can be used against irregular surfaces.

Abstract: A method of detecting defects in structures, comprising the steps of inducing mechanical energy in a structure via the emission of a broad-band acoustic signal, and capturing over a time interval a plurality of images of the structure each of the plurality of images comprised of a plurality of pixels arranged in a plurality of rows and columns each indicative of an intensity of infrared energy emitted by a portion of the structure.

Abstract: A method and apparatus for calibrating an acoustic thermography system 10 and/or enhancing the flaw detection abilities of such a system is provided. The method allows applying a material (e.g., 103) to a specimen 12 undergoing acoustic thermography inspection. The material is thermally responsive to acoustic energy transmitted to the specimen by the acoustic thermography system. In one aspect thereof, a thermal response of the material applied to the specimen when subjected to acoustic energy is processed to determine whether the level of acoustic energy applied by the acoustic thermographic system appropriately meets a desired amount of acoustic energy for inspecting the specimen. In another aspect thereof, the thermal response of the specimen in combination with the applied material may be processed to determine whether certain types of flaws (e.g.

Abstract: A flaw inspection system (10) contains a substrate (12) to be inspected, such as a generator tube wall, a rotor of a generator, an aircraft skin, having or thought to have interior defects (24, 26) such as stress cracks, where the substrate (12) has attached reference blocks (14, 16) also containing defects (18, 20) of the type that might be found in the substrate, where an ultrasonic generator (28) emits sound waves (30) which contact all the defects, causing heat (32) which is sensed by a thermal camera (50) which, in association with a controller (54) causes images (60, 62) to appear on a monitor (52) from which the type and number of defects (24, 26) in the substrate (12) can be determined.

Abstract: A method and apparatus for testing a material such as the water-wall tubes in boilers includes the use of a portable thermal line heater having radiation shields to control the amount of thermal radiation that reaches a thermal imager. A procedure corrects for variations in the initial temperature of the material being inspected. A method of calibrating the testing device to determine an equation relating thickness of the material to temperatures created by the thermal line heater uses empirical data derived from tests performed on test specimens for each material type, geometry, density, specific heat, speed at which the line heater is moved across the material and heat intensity.

Abstract: A defect detection system for thermally imaging a structure that has been energized by a sound energy. The system includes a transducer that couples a sound signal into the structure, where the sound signal causes defects in the structure to heat up. In one embodiment, the sound signal has one or more frequencies that are at or near an eigen-mode of the structure.

Abstract: A method of infrared thermography is described. The invention utilizes a high resolution infrared thermography system and associated computer in conjunction with a test chamber to determine heat transfer coefficients and film effectiveness values from a single test.

Abstract: The present invention relates to a device for detecting the thermal conductivity by application of optical pulse techniques. A sample preheated in a furnace is exposed to energy by means of an optical pulse. The temperature profile in the sample is recorded by means of an infrared sensor. The thermal conductivity of the sample can then be detected by mathematical derivation. To reduce tho influence of the time history of the optical pulse on measurement, a measuring means is provided for determining this history, An analyzer unit then derives therefrom the corrected temperature profile.

Abstract: In thermography apparatus, a lamp 102 is modulated sinusoidally and a camera 106 captures thermal images at the modulated frequency, but delayed by an adjustable preset delay. A signal delay box 107 is connected between a sinusoidal modulation signal function generator 104 and the camera 106. The delay box introduces a delay to the function generator signal so that the thermal image is captured after a period of time, resulting in an enhanced image.

Abstract: A method for reconstructing internal surface geometry of a part includes registering a thickness map for the part with external surface data for the part. The thickness map has a number of thickness data. Internal surface data is generated using the thickness map and the external surface data to reconstruct the internal surface geometry.

Abstract: A method of determining the analyte concentration of a test sample is described. A temperature gradient is introduced in the test sample and infrared radiation detectors measure radiation at selected analyte absorbance peak and reference wavelengths. Reference and analytical signals are detected. In the presence of the selected analyte, parameter differences between reference and analytical signals are detectable. These parameter differences, having a relationship to analyte concentration, are measured, correlated, and processed to determine analyte concentration in the test sample. Accuracy is enhanced by inducing a periodically modulated temperature gradient in the test sample. The analytical and reference signals may be measured continuously and the parameter difference integrated over the measurement period to determine analyte concentration.

Abstract: A defect detection system for thermally imaging a structure that has been energized by a sound energy. The system includes a transducer that couples a sound signal into the structure, where the sound signal causes defects in the structure to heat up. In one embodiment, a non-linear coupling material is positioned between the transducer and the structure to couple the sound energy from the transducer to the structure. A predetermined force is applied to the transducer and a pulse duration and a pulse frequency of the sound signal are selected so that the sound energy induces acoustic chaos in the structure, thus generating increased thermal energy. A thermal imaging camera images the structure when it is heated by the sound signal.

Abstract: A method and device for photothermal imaging tiny metal particles which are immersed in a given medium like a living cell. The given medium and immersed tiny metal particles are illuminated through separate phase reference laser beam and sensitive probe laser beam, with the sensitive probe laser beam undergoing through impingement on the given medium slight phase changes induced by photothermal effect due to a local heating thanks to a heating laser beam, in the absence of any substantial phase changes to the phase reference laser beam. Illuminating is performed by focusing the separate phase reference laser beam. The induced slight phase changes on the sensitive probe laser beam with reference to the phase reference laser beam are detected through differential phase interference contrast phenomenon so as to allow each of the tiny metal particles in the given medium to be imaged as an optical label.

Abstract: Mesoporous silica is shown to be a sample holder for laser desorption/ionization of mass spectrometry. Supported mesoporous silica was prepared by coating an ethanolic silicate solution having a removable surfactant onto a substrate to produce a self-assembled, ordered, nanocomposite silica thin film. The surfactant was chosen to provide a desired pore size between about 1 nanometer diameter and 50 nanometers diameter. Removal of the surfactant resulted in a mesoporous silica thin film on the substrate. Samples having a molecular weight below 1000, such as C60 and tryptophan, were adsorbed onto and into the mesoporous silica thin film sample holder and analyzed using laser desorption/ionization mass spectrometry.

Abstract: A method and apparatus of determining the analyte concentration of a test sample is described. A temperature gradient is introduced into the test sample and infrared radiation detectors measure radiation at selected analyte absorbance peak and reference wavelengths. The modulation of the temperature gradient is controlled by a surface temperature modulation. A transfer function is determined that relates the surface temperature modulation to the modulation of the measured infrared radiation. Reference and analytical signals are detected. In the presence of the selected analyte, phase and magnitude differences in the transfer function are detected. These phase and magnitude differences, having a relationship to analyte concentration, are measured, correlated and processed to determine analyte concentration in the sample.

Abstract: Systems and methods for measuring the flow of a liquid along a conduit are disclosed. A heat source applies thermal energy to a portion of a liquid flowing along a conduit thereby elevating its temperature. An optical sensing means comprising a light source illuminating the liquid in the conduit downstream from the position of application of the thermal energy and an optical detector receiving a portion of this illumination senses the heated portion of liquid by measures a change in an optical property of the illumination caused by a change in the index of refraction of the heated portion of liquid. The time required for the heated portion of the liquid to move from the point of application of thermal energy to the point of optical sensing is measured. This measured time, along with the distance of separation of the heat source and the optical sensing means permits calculation of the velocity of the liquid in the conduit.

Abstract: A method and apparatus for recognizing foreign material (2), in particular adhesive objects, glue or joints, on or in bank notes (1), including detecting the thermal radiation (5) emanating from at least a partial area of the bank note (1): and recognizing foreign material (2) located on the bank note (1) on the basis of the detected thermal radiation (5). The invention is especially suitable for recognizing adhesive objects, in particular adhesive tape and joints, on bank notes since areas of a bank note with adhesive tape or joints differ very distinctly in their thermal properties from other areas of the bank note without adhesive tape.

Abstract: In a method and apparatus for making and inspecting pre-fastened articles, such as disposable training pants, having at least two generally flexible elements capable of connection with each other during initial assembly of the article, the elements are arranged in overlapping relationship with each other and connected together to define an engagement seam of the article. The article is arranged to define an interior space thereof whereby the interior space is bounded in part by the engagement seam. The elements are irradiated at the engagement seam by a radiation source within the interior space of the article and an image of the irradiated engagement seam is captured by an image capturing device. In one embodiment, the image capturing device is positioned within the interior space of the article and the radiation source is either within the interior space or exterior of the article.

Abstract: A method facilitates inspection of a component surface. The method comprises positioning a surface of the component to be inspected in an optical path of at least one infrared radiation detector, heating the component surface using electromagnetic radiation to cause an increase in radiance from a defect present at the component surface, and detecting temperature variations within the component surface using the at least one infrared radiation detector, such that the surface irradiance is measured at predetermined locations across the component surface. The method further comprises detecting cracks in the component by analyzing radiation transient response data received by the infrared radiation detector, and correlating the temperature variations to the radiation transient response data to determine a depth of the detected cracks.

Abstract: Methods and apparatus for screening diverse arrays of materials using infrared imaging techniques are provided. Typically, each of the individual materials on the array will be screened or interrogated for the same material characteristic. Once screened, the individual materials may be ranked or otherwise compared relative to each other with respect to the material characteristic under investigation. According to one aspect, infrared imaging techniques are used to identify the active sites within an array of compounds by monitoring the temperature change resulting from a reaction. This same technique can also be used to quantify the stability of each new material within an array of compounds. According to another aspect, identification and characterization of condensed phase products is achieved, wherein library elements are activated by a heat source serially, or in parallel.

Abstract: A system and method for using terahertz radiation to detect and monitor a substance undergoing a change in phase from a liquid phase to a solid phase or vice-versa is disclosed. By employing terahertz radiation in either the pulsed mode or in the continuous-wave (CW) mode, the system can non-invasively monitor these changes. The system uses the principle that matter in a liquid state will absorb and attenuate terahertz radiation to a larger degree than matter in a semisolid or solid state. Most terahertz radiation absorption occurs due to the rotational motions of molecules, i.e. either whole molecules or groups of atoms rotating about molecular bonds.

Abstract: Described are methods and systems for providing improved defect detection and analysis using infrared thermography. Test vectors heat features of a device under test to produce thermal characteristics useful in identifying defects. The test vectors are timed to enhance the thermal contrast between defects and the surrounding features, enabling IR imaging equipment to acquire improved thermographic images. In some embodiments, a combination of AC and DC test vectors maximize power transfer to expedite heating, and therefore testing. Mathematical transformations applied to the improved images further enhance defect detection and analysis. Some defects produce image artifacts, or “defect artifacts,” that obscure the defects, rendering difficult the task of defect location. Some embodiments employ defect-location algorithms that analyze defect artifacts to precisely locate corresponding defects.

Abstract: A method and system (100) for enhancing the determination of the presence of a surface breaking or subsurface defect with an object (114) under test are provided (FIG. 1). The method can include transferring ultrasonic energy to an object (114) under test and sensing images (514, 514?) of the object (114) under test before and after transferring ultrasonic energy to the object (114) with an infrared thermography camera (112). An increase in temperature gradients in the areas adjacent a defect (516, 516?) is shown in the images (514, 514?) produced by the camera (112), which indicates the presence of the defect (516, 516?). The temperature gradients in the area of the defect (516, 516?) and images of the defect (516, 516?) can be displayed to enable users to determine the temperature gradient and thus the extent of the defect (516, 516?). Digital images (514, 514?) of the before and after transferring ultrasonic energy can be superimposed (514?) to identify and illustrate the defect (516?).

Abstract: A hand-held sound source for use in an infrared or thermal imaging system that detects sub-surface defects in a structure. The sound source includes a transducer that is positioned against the structure to emit a sound signal into the structure. The sound source further includes an adjustable spring that pushes the transducer against the structure with a predetermined amount of force so that the sound energy is effectively coupled into the structure. The sound source also includes three stabilizing legs that stabilize the transducer on the structure. The length of each leg can be adjustable relative to the length of the other legs so that the sound source can be used against irregular surfaces.

Abstract: An electron beam lithography apparatus, which uses a patterned emitter, includes a pyroelectric plate emitter that emits electrons using a patterned metal thin layer formed on the pyroelectric plate as a mask. When the emitter is heated, electrons are emitted from portions of the emitter covered with a patterned dielectric layer, and not from portions of the emitter covered with a patterned metal thin layer, and a pattern of the emitter is thereby projected onto a substrate. To prevent dispersion of emitted electron beams, the electron beams may be controlled by a permanent magnet, an electro-magnet, or a deflector unit. A one-to-one or x-to-one projection of a desired pattern on the substrate is thereby obtained.

Abstract: A method of detecting defects in structures, comprising the steps of inducing mechanical energy in a structure via the emission of a broad-band acoustic signal, and capturing over a time interval a plurality of images of the structure each of the plurality of images comprised of a plurality of pixels arranged in a plurality of rows and columns each indicative of an intensity of infrared energy emitted by a portion of the structure.

Abstract: The simultaneous multi-frequency excitation with two or more discrete frequencies of an electrically modulatable hot light source enables the parallel evaluation corresponding to the different drive frequencies. As a result thereof, the measuring time in the measurement of multi-layer systems is significantly shortened. As a result of a suitable selection of the discrete frequency parts of the drive frequencies, these can be adapted to the measurement problem.

Abstract: A thermal imaging method to detect heat flows from naturally-heated subsurface objects. The method uniquely combines precise, emissivity-corrected temperature maps, thermal inertia maps, temperature simulations, and automatic target recognition to display clear, clutter-free, three-dimensional images of contained hollow objects or structures, at depths to 20 times their diameter. Temperature scans are corrected using two different infrared bands. Co-registered object-site temperature scans image daily and seasonal temperature-spread differences, which vary inversely as the object's and surrounding host material's thermal inertias. Thermal inertia (resistance to temperature change) is the square root of the product (k&rgr;C), for thermal conductivity, k, density, &rgr; and heat capacity, C.

Abstract: Material analysis apparatus and method, particularly of use in detecting barely visible impact damage but also of use to detect other material characteristics. The apparatus includes a function generator which provides a sinusoidal signal to an ultrasonic amplifier as well as to a PC. The PC is connected to an infrared camera. The sinusoidal signal is fed into the amplifier and causes two probes attached to the sample of material to emit ultrasonic energy at the modulated frequency. Ultrasonic energy from the two probes then enters the sample by means of mechanical coupling and an image of the resulting thermal radiation is captured by the infrared camera and transferred to the PC for further processing and analysis.

Abstract: A system and method utilizing a radiation source with a wavelength near 2 &mgr;m (preferably 1993 nm) to measure the presence of ammonia, carbon dioxide and water vapor using spectroscopic techniques and a reduced measurement pressure is provided. Using radiation substantially near 2 &mgr;m enables one to interrogate the PP3(3)s ammonia transition at a frequency of 5016.977 cm−1, which is isolated from water and carbon dioxide interference; the P(32) carbon dioxide transition at 5017.030 cm−1, which is isolated from both ammonia and water interference, and a water transition at 5017.100 cm−1. Moreover, a tunable radiation source that can sweep over the aforementioned ammonia and carbon dioxide and water features can measure the concentrations of all three species simultaneously.

Abstract: The invention relates to a method and to a device for testing electronic circuits or the parts thereof on printed circuits. The inventive method comprises the following steps: (a) detecting the radiation that is emitted by the surface of the printed circuit, (b) converting the detected radiation to data that represent a surface structure and/or depth structure of the printed circuit, (c) comparing the data of the surface structure and/or the depth structure with stored data of a desired state of the surface structure and/or depth structure, and (d) determining any deviations between the data of the detected surface structure and/or depth structure and the data of the desired state of the surface structure and/or depth structure.

Abstract: A portable thermal imaging apparatus uses an ultrasonic acoustical source and an infrared camera to examine a flat or curved specimen such as the surface of the fuselage of an aircraft for defects such as subsurface disbonds, delaminations, cracks, corrosion, embedded contaminants, inclusions, and voids. The apparatus includes a base framework removably attachable to the specimen by a set of vacuum cups and a pair of guide rails along which the imaging apparatus can travel to allow multiple images to be captured without relocating the apparatus on the specimen. The acoustical signal from the ultrasonic source sweeps over a range of frequencies in order to excite defects of greatly differing size to exhibit local heating.

Abstract: A thermal imaging system for detecting cracks and defects in a structure. An ultrasonic transducer is coupled to the structure through a malleable coupler. Ultrasonic energy from the transducer causes the defects to heat up, which is detected by a thermal camera. A control unit is employed to provide timing and control for the operation of the ultrasonic transducer and the camera.

Abstract: The invention relates to an infrared camera comprising detector means (2) sensitive for infrared radiation and optics for focusing an object (4) to be monitored on the detector means. A light source (8; 8′; 12; 17) is emitting a narrow beam within the visible wavelength region towards the object (4) to be imaged by the detector means.

Abstract: A method and device for photothermal imaging tiny metal particles which are immersed in a given medium like a living cell deposited onto a transparent glass slide. The given medium and immersed tiny metal particles are illuminated through separate phase reference laser beam and sensitive probe laser beam, with the sensitive probe laser beam including a heating laser beam undergoing through impingement on the given medium slight phase changes induced by photothermal effect due to a local heating, in the absence of any substantial phase changes to the phase reference laser beam. Illuminating is performed by focusing the separate phase reference and sensitive probe laser beam through the transparent glass slide at a given depth within the given medium and a transmitted phase reference laser beam and a transmitted sensitive probe laser beam undergoing the slight phase changes are generated.

Abstract: A portable thermal imaging analysis for analyzing a specimen includes a frame removably attachable to the specimen by a vacuum and suction cups. The apparatus also includes a sound source and thermal imaging camera that generates thermal images of the specimen along with a controller connected to the sound source and the imaging camera.

Abstract: A microwave-enhanced infrared thermography technique for detecting buried objects exploits varying phase shifts experienced by different-frequency microwave signals reflected from objects back toward the surface, the phase shifts resulting in different interference patterns and therefore different temperature distribution patterns near the surface. Respective infrared images of an area are captured prior to microwave heating, after a first heating with a first frequency, and after heating with a second frequency different from the first. Pairs of the images are subtracted to form temperature rise images showing patterns of temperature rise in the two cycles, and the temperature rise images are subtracted to form a difference image which is analyzed to identify characteristics indicating the presence of buried objects.

Abstract: Thermal response of a turbine component to application of thermal stimuli is automatically analyzed by regions of interest. Each region may be analyzed for conformance for a number of thermal response metrics, in an absolute sense, and/or relative to each other. The thermal response metrics may include the temperature threshold a particular region (e.g. the reference/primary region) exhibits a critical response size, and that the sub-region achieving the critical response size at the temperature threshold also has a critical shape. The analyses may be performed using the pixel values of the constituting pixels of a picture frame of the turbine component's thermal response. A binary passed or failed conclusion may be reached based on the results of the automated analyses.

Abstract: A method and system (100) for enhancing the determination of the presence of a surface breaking or subsurface defect with an object (114) under test are provided (FIG. 1). The method, for example, can include transferring ultrasonic energy to an object (114) under test and sensing images (514, 514′) of the object (114) under test before and after transferring ultrasonic energy to the object (114) with an infrared thermography camera (112). An increase in temperature gradients in the areas adjacent a defect (516, 516′) is shown in the images (514, 514′) produced by the camera (112), which indicates the presence of the defect (516, 516′). The temperature gradients in the area of the defect (516, 516′) and images of the defect (516, 516′) can be displayed to enable users to determine the temperature gradient and thus the extent of the defect (516, 516′).

Abstract: A defect detection system for thermally imaging a structure that has been energized by a sound energy. The system includes a transducer that couples a sound signal into the structure, where the sound signal causes defects in the structure to heat up. In one embodiment, the sound signal has one or more frequencies that are at or near an eigen-mode of the structure. In another embodiment, an on-linear coupling material is positioned between the transducer and the structure to couple the sound energy from the transducer to the structure. A predetermined force is applied to the transducer and a pulse duration and a pulse frequency of the sound signal are selected so that the sound energy induces acoustic chaos in the structure, thus generating increased thermal energy. A thermal imaging camera images the structure when it is heated by the sound signal.

Abstract: To measure the flow rate of coolant through a cooling hole of a film-cooled part, a transient thermal response of an external surface temperature of the film-cooled part is measured and the transient thermal response is characterized mathematically. From the mathematical characterization, the flow rate through the film hole is determined.

Abstract: A method and apparatus of determining the analyte concentration of a test sample is described. A temperature gradient is introduced into the test sample and infrared radiation detectors measure radiation at selected analyte absorbance peak and reference wavelengths. The modulation of the temperature gradient is controlled by a surface temperature modulation. A transfer function is determined that relates the surface temperature modulation to the modulation of the measured infrared radiation. Reference and analytical signals are detected. In the presence of the selected analyte, phase and magnitude differences in the transfer function are detected. These phase and magnitude differences, having a relationship to analyte concentration, are measured, correlated and processed to determine analyte concentration in the sample.

Abstract: A device and method for determining analyte concentrations within a material sample are provided. A modulating temperature gradient is induced in the sample and resultant, emitted infrared radiation is measured at selected analyte absorbance peaks and reference wavelengths. The modulating temperature gradient is controlled by a surface temperature modulation. One embodiment provides a transfer function relating the surface temperature modulation to a modulation of the measured infrared radiation. Phase and magnitude differences in the transfer function are detected in the presence of the sought-after analyte. These phase and magnitude differences, having a relationship to analyte concentration, are measured, correlated and processed to determine analyte concentration in the material sample. Another embodiment provides a method for transforming thermal phase spectra to absorption spectra for consistent determination of analyte concentration within the sample.

Abstract: A method and infrared thermal imaging apparatus detects normal and angled cracks on or beneath a sample surface using infrared thermal imaging where the crack plane is perpendicular or angled to an imaged surface of the sample. A constant heating source is used for heating a section of the sample to produce a lateral heat transfer through the sample. An infrared camera is positioned near one side of the sample for receiving thermal image data resulting from the lateral heat transfer through the sample. A data acquisition and processing computer is used for acquiring and differentiation processing thermal image data from the infrared camera for generating two-dimensional first derivative and second derivative images to detect the normal and angled cracks.

Abstract: The present invention relates to a device for detecting the thermal conductivity by application of optical pulse techniques. A sample preheated in a furnace is exposed to energy by means of an optical pulse. The temperature profile in the sample is recorded by means of an infrared sensor. The thermal conductivity of the sample can then be detected by mathematical derivation. To reduce the influence of the time history of the optical pulse on measurement a measuring means is provided for determining this history. An analyzer unit then derives therefrom the corrected temperature profile. In order to reduce the influence of the time history of the optical pulse on measurement a measuring means is provided for determining this history. An analyzer unit then derives therefrom the corrected temperature profile.

Abstract: A plurality of system checks on a turbine component inspection system are monitored, and an end user interface element to cause an inspection of a turbine component to commence is enabled only upon determining based on the monitored system checks that the inspection system is in a predetermined state of readiness, thereby ensuring each turbine component inspected is stimulated with thermal stimulus having the same characteristics. Further, a binary passed or failed indicator is displayed to unequivocally inform the operator whether a turbine component being inspected passed or failed the inspection. In a preferred embodiment, thermal images of a turbine component's response to applied thermal stimulus, as well as status of automatically launched quantitatively analyses on the turbine component's response to the applied thermal stimulus are also displayed.

Abstract: In an apparatus for reading codes of a thermoluminescence detector, a housing including an optical unit is disposed on a base together with a disc-like magazine, which is rotatably supported adjacent the housing and provided with an annular array of recesses receiving the thermoluminescence detectors to be examined. The housing has a side opening through which the magazine extends into the housing, in which a light source is disposed for the homogeneous illumination of the thermoluminescence detectors from one side thereof, A CCD camera is disposed in the housing at the other side of the magazine for recording the illuminescence generated by the detectors when exposed to the light from the light source for determining the radiation exposure of thermoluminescence detectors.

Abstract: A method and infrared thermal imaging apparatus detects normal and angled cracks on or beneath a sample surface using infrared thermal imaging where the crack plane is perpendicular or angled to an imaged surface of the sample. A constant heating source is used for heating a section of the sample to produce a lateral heat transfer through the sample. An infrared camera is positioned near one side of the sample for receiving thermal image data resulting from the lateral heat transfer through the sample. A data acquisition and processing computer is used for acquiring and differentiation processing thermal image data from the infrared camera for generating two-dimensional first derivative and second derivative images to detect the normal and angled cracks.