Abstract: A method is provided for detecting the spalling off of a significant portion of buildup of alkali and/or metal from the refractory lining of a metallurgical furnace. The method includes monitoring the rate of change of temperature of the refractory lining at a plurality of spaced locations and determining when the rate of change of temperature at a predetermined number of such locations exceeds a first threshold level that a significant portion of buildup has spalled off. The invention is particularly applicable to blast furnaces and permits the addition of heat to be made to the molten metal in the furnace before the spalled off portion descends through the furnace shaft and reaches the molten metal.

Abstract: In an infrared (IR) transient thermography system a sequence of image frames is acquired from an IR sensitive focal-plane array camera. Each sequentially acquired image frame is made up of an array of pixels and has assigned a frame-number that corresponds to elapsed time. Temperature-versus-time (T-t) data corresponding to each pixel is developed from stacks of sequential image-frames. A method of analyzing the stacks of thermal data image-frames is presented wherein either the Real or the Imaginary component portions of a Fast-Fourier Transform of a normalized T-t data curve from each pixel is used to determine the thickness of an object and produce a color-keyed or gray-scale coded thickness map.

Abstract: In an infrared (IR) transient thermography system a sequence of image frames is acquired from an IR sensitive focal-plane array camera. Each sequentially acquired image frame is made up of an array of pixels and has assigned a frame number that corresponds to elapsed time. A method of analyzing thermal imaging data-frames is presented wherein a synthetically generated temperature-time reference curve is used to determine pixel contrast-versus-time data.

Abstract: Method and apparatus for photothermal analysis of a layer of material, especially for thickness measurement thereof. The invention relates to a method of photothermal analysis of a layer of material, especially of measuring the thickness of a layer, wherein the surface of a first layer of material is excited by electromagnetic radiation and heat radiation emitted by said surface and having a first temperature response curve is detected, the surface of a second layer of material is excited and heat radiation emitted by said surface and having a second temperature response curve is detected, the first layer of material being a reference layer and the second layer of material being the layer of material to be analyzed. A stretch factor is determined between the first and second temperature response curves, and the stretch factor is used as a characteristic factor for the ratio between the layer of material to be analyzed and the reference layer.

Abstract: Glide heads for the detection of asperities on a storage disc have a thermal transducer oriented along the air bearing surface. The thermal transducer generally is in electrical contact with a circuit to measure the electrical resistance of the thermal transducer. Preferred methods of depositing the thermal transducer involve the deposition of the thermal transducer on the smooth surface of a wafer prior to the slicing of individual sliders.

Abstract: There are provided an inline inspection system and inspection method for inspecting the substrate surface on which semiconductors and circuit patterns are formed by radiating thereto white beam, laser beam or electron beam, and reviewing, inspecting and discriminating the detected roughness and figure defect, particle and moreover electrical defect on the surface with higher accuracy within a short period of time with the same instrument. Thereby, automatic movement to the position to be reviewed, acquisition of image and classification can be realized.

Abstract: An improved media defect glide test head assembly which incorporates a wide thermo-resistive (TR) element suitable for detection of thermal asperities on the surfaces of magnetic recording discs. The TR element of the inventive glide test head assembly is very wide when compared to magneto-resistive (MR) elements in normal MR read/write heads. In the currently preferred embodiment, the TR element is envisioned to be as wide as is possible to fabricate on the trailing edge of an air bearing element of the glide test head assembly, to enable detection of thermal asperities across a relatively wide band of disc surface during each disc rotation, thus enabling rapid testing of the media surface. In a second aspect of the invention, the wide TR element is envisioned to be formed of nickel or other material having a large thermal resistance coefficient.

Abstract: In a method of fabricating a substrate, a substrate is submerged into a chemical bath so that the thickness of the substrate changes. The temperature of the chemical bath is monitored to ascertain a change in the thickness of the substrate.

Abstract: An apparatus for detecting surface variations on a rotating disc includes a slider, suspension assembly, first surface variation sensor, second surface variation sensor, and a controller. The slider is adapted to fly over the disc. The suspension assembly is coupled to the slider to position the slider over the disc. The first surface variation sensor is disposed on the slider, and provides a first sensor signal based upon slider contact with one of the surface variations. The second surface variation sensor is disposed on the slider and spaced from the first surface variation sensor. The second surface variation sensor provides a second sensor signal based upon slider contact with the surface variation. The controller receives the first and second signals and calculates a position of the surface variation based upon the first and second sensor signals.

Abstract: A high temperature fouling test unit is provided. The fouling test unit includes a flow tube with a fouling probe received within the flow tube. The fouling probe includes a heated section. An annular passage is defined between the fouling probe and the flow tube. An impeller is mounted within the flow tube for inducing fluid flow within the annular passage. A plurality of temperature responsive devices monitor a rate of heat transfer and a change in fluid temperature through the annular passage.

Abstract: Apparatus and methods for calibrating a thermal proximity sensor are disclosed. Thermal responses from a thermal proximity sensor are used to sense the instantaneous distance between the sensor and a medium over which the sensor is moved, in a data storage system. Sensing the instantaneous distance results in detection of topographical variations on the medium. Calibration techniques for the sensor are disclosed herein and involve, in one aspect, using primarily electrical measurements to calibrate the sensor; and in another aspect, varying the distance between the sensor and the medium, obtaining actual thermal responses from the sensor, and using the actual responses (via direct comparison or curve fitting) to calibrate the sensor. In one embodiment, the sensor is a magnetoresistive access element used to access data on the medium.

Abstract: A method and a portable apparatus for the nondestructive identification of defects in structures. The apparatus comprises a heat source (20) and a thermal imager (30) that move at a constant speed past a test surface (10) of a structure. The thermal imager (30) is off set at a predetermined distance from the heat source (10). The heat source (10) induces a constant surface temperature. The imager (20) follows the heat source (10) and produces a video image of the thermal characteristics of the test surface. Material defects produce deviations from the constant surface temperature that move at the inverse of the constant speed. Thermal noise produces deviations that move at random speed. Computer averaging of the digitized thermal image data with respect to the constant speed minimizes noise and improves the signal of valid defects. The motion of thermographic equipment coupled with the high signal to noise ratio render it suitable for portable, on site analysis.

Abstract: A method is provided for extending the life of a refractory lining of a blast furnace hearth. The refractory hearth has temperature probes embedded in the floor and walls thereof. The method includes periodically measuring temperatures indicated by the probes and determining the campaign maximum and current average temperature readings to locate two solidification isotherm representing the wear line of the refractory and the inner surface of the protective metal layer. The thickness of the protective layer is determined from the distance between the solidification isotherms representing the refractory wear line and the inner surface of the metal skull. From this determination sufficient thickness of the protective layer is maintained during actual operation of the furnace.

Abstract: A method is provided for determining the thickness of a protective layer of solidified metal skull formed on the refractory hearth of a blast furnace. The refractory hearth has temperature probes embedded in the floor and walls thereof. The method includes periodically measuring temperatures indicated by the probes and determining the campaign maximum and current average temperature readings to locate two solidification isotherms representing the wear line of the refractory and the inner surface of the protective metal layer. The thickness of the protective layer is determined from the distance between the solidification isotherms representing the refractory wear line and the inner surface of the metal skull.

Abstract: A method of determining the conditions of heat transfer at the interface of the refractory and a metal shell of the furnace by calculating the interface temperature from thermoprobes in the refractory and then from a thermoprobe in the metal shell and the temperature of cooling water applied to the shell, and comparing these interface temperatures to determine whether a gap has formed between the refractory and shell and whether cooling of the shell is sufficient.

Abstract: A brake lining wear indicator utilizes a temperature sensor assembly embedded in a brake lining of a drum brake assembly. The temperature sensor assembly includes two temperature sensors with a first temperature sensor located at a first distance X from the wear surface of the brake lining and a second temperature sensor located at a second distance X+d from the wear surface. A timing device measures the time period for the first temperature sensor to reach a first predetermined temperature and measures the time period for the second temperature sensor to reach a second predetermined temperature. The remaining useful thickness of the brake lining is determined based on the ratio of the respective time periods. Thus, the indicator provides a time-temperature based determination of when the brake linings should be replaced.

Abstract: A method and apparatus for mapping the character and location of medium conditions for a planar surface. Energy is supplied to a head in close proximity to the planar surface to thereby raise the temperature of the object. The head is moved with respect to the planar surface while keeping the distance from the planar surface substantially constant. An increase, decrease or a rapid variation containing positive and negative temperature excursions is distinguished by electronic means. These variations are used to categorize disturbances or contact with the medium, and the location and type of condition is recorded in hard copy or by computer acquisition for later consideration in the file manufacture process. Additionally, magnetic and thermal information may be combined to provide an even more complete description of the nature of the condition, since the magnetic and thermal signals are descriptive of different physical phenomenon.

Abstract: Apparatus and methods for calibrating a thermal proximity sensor are disclosed. Thermal responses from a thermal proximity sensor are used to sense the instantaneous distance between the sensor and a medium over which the sensor is moved, in a data storage system. Sensing the instantaneous distance results in detection of topographical variations on the medium. Calibration techniques for the sensor are disclosed herein and involve, in one aspect, using primarily electrical measurements to calibrate the sensor; and in another aspect, varying the distance between the sensor and the medium, obtaining actual thermal responses from the sensor, and using the actual responses (via direct comparison or curve fitting) to calibrate the sensor. In one embodiment, the sensor is a magnetoresistive access element used to access data on the medium.

Abstract: In a device for photothermically testing a surface (1) of a moving test specimen (2), an excitation beam (5) may be applied to a test area (13). The excitation beam (5) passes through an aperture (12) in a collecting lens (11) that reproduces the thermal radiation generated in a measuring area (14), so that the collecting lens (11) may be adapted to a wavelength of the excitation beam (5) passed to a detector (20). A coupling mirror (9) mounted in the path of excitation beam (5) has practically total reflectivity for the wavelength of the excitation beam (5) and is arranged in such a way that it is very small near the focal area of the excitation beam (5), so that together with the aperture (12) of the collecting lens (11) it only masks a small part of the thermal radiation (17) passed to the detector (20).

Abstract: Thermal, optical, physical and chemical characteristics of a substrate (11) surface are determined with non-contact optical techniques that include illuminating (23) the surface with radiation having a ripple intensity characteristic (51), and then measuring the combined intensities (53) of that radiation after modification by the substrate surface and radiation emitted from the surface. Precise determinations of emissivity, reflectivity, temperature, changing surface composition, the existence of any layer formed on the surface and its thickness are all possible from this measurement. They may be made in situ and substantially in real time, thus allowing the measurement to control (39, 41) various processes of treating a substrate surface. This has significant applicability to semiconductor wafer processing and metal processing.

Abstract: Apparatus and methods for improved thermal proximity imaging are provided. A data storage medium surface is moved relative to a sensor, in one embodiment a magnetoresistive read/write element. Topographical variations on the storage medium induce temperature changes in the sensor. These temperature changes are monitored to detect the location and nature (e.g., height) of the topographical variations on the medium surface. A feedback circuit using an impedance bridge is disclosed for sensing instantaneous changes in the temperature of the sensor, correcting for the changes and, therefore, keeping the temperature of the sensor substantially constant. By keeping the temperature of the sensor constant, the topographical variations can be detected without any adverse impacts of the surrounding thermal environment on the detection response time.

Abstract: A radiometer is described which coherently detects the thickness of oil films on water by converting continuous-frequency microwave or millimeter-wave brightness temperature versus frequency measurements from the frequency/wavenumber domain to the oil-film-thickness domain (received power versus film thickness).

Abstract: A on-line monitoring system of a simulated heat-exchanger which includes a plurality of temperature sensors adapted to detect the temperatures of cold water and hot water at respective water inlets and water outlets, a flowrate detector adapted to detect the flow rate of cold water, an A/D converter adapted to convert detected temperature signals and flowrate signal into corresponding digital signals, and a microprocessor adapted to calculate total heat transmission rate subject to the data obtained from the A/D converter and to calculate the heat transmission constant of the heat exchanging tube inside the heat exchanging chamber, then to store the calculated data in a memory for use as a reference value for the calculation of a next heat transmission rate so as to further calculate the heat transmission rate and thickness of fouling of the heat exchanging tube by comparing the latest coefficient of heat transmission with the previous coefficient of heat transmission, permitting the calculated result to be s

Abstract: A system for determining the cleanliness of a boiler having a plurality of tube banks by obtaining a temperature profile of the boiler heat transfer surfaces includes extending an extension arm, such as a soot blower lance, near the tube banks of the boiler. A separate temperature reading is taken at intervals along the length of the extension arm by utilizing either a plurality of infrared non-contact temperature sensors or a plurality of optical fibers. Each separate temperature reading enables a temperature profile to be determined along the length of the extension arm which, in turn, allows deposit accumulation on the tube banks to be determined.

Abstract: A method and apparatus for mapping the character and location of small surface variations on a planar surface. Energy is supplied to an object in close proximity to the planar surface to thereby raise the temperature of the object. The object is moved with respect to the planer surface substantially constant. A decrease in temperature of the object is detected when it is in proximity to the variation to define the location and character of the variation. The energy supply may be thermal energy or optical energy but preferably is electrical energy which heats a resistive element. Preferably, the object is the magnetoresistive head of a disk drive assembly. The surface may be that of a magnetic recording material. The change in temperature is detected by monitoring the resistance of the magnetoresistive coil of the head. The energy may be supplied in pulses to obtain higher peek temperatures while avoiding mechanical distortion of the object.

Abstract: Thermal, optical, physical and chemical characteristics of a substrate (11) surface are determined with non-contact optical techniques that include illuminating (23) the surface with radiation having a ripple intensity characteristic (51), and then measuring the combined intensities (53) of that radiation after modification by the substrate surface and radiation emitted from the surface. Precise determinations of emissivity, reflectivity, temperature, changing surface composition, the existence of any layer formed on the surface and its thickness are all possible from this measurement. They may be made in situ and substantially in real time, thus allowing the measurement to control (39, 41) various processes of treating a substrate surface. This has significant applicability to semiconductor wafer processing and metal processing.

Abstract: A method and system for probing a volume of material by detecting local conductivity in the material using microwave radiation. The probed volume of material is exposed to microwave radiation of a wavelength selected to excite the carriers of electrical current and induce localized heating in regions of the volume of material which is an electronic material or a device. A thermographic imaging system detects size and distribution of the locally heated regions, and a processing system determines a selected property of the material by analyzing the size and distribution of the locally heated regions. The thermographic imaging system can be an infra-red imaging system which detects infra-red radiation emitted from the locally heated region, or it can be a system which deposits a thermally sensitive film onto a surface of the material and detects thermally induced changes in the deposited film caused by the transferred heat.

Abstract: A device for non-destructively and continuously measuring and monitoring the thickness of a shaped section includes an extruder for extruding a thermoplastic material to form a shaped section having a temperature variation extending along a length of said section, at least one unit for measuring and detecting radiation emitted by the section during movement of the shaped section from the extruder and at least one unit for causing the radiation detecting and measuring unit to scan the entire outer surface of the shaped section. The detecting and measuring unit being connected to a computer system including imaging processing software, a radiation recording unit and a display screen for determining a variation in the thickness of the shaped section based on a variation of emitted radiation detected by the detecting and measuring unit.

Abstract: A method for evaluating the type, extent, and threshold of fouling in a heat exchanger test tube by using a reference test block to measure a reference thermal relaxation time at a guaranteed clean reference section of a heat exchanger test tube and comparing the reference thermal relaxation time with thermal relaxation times measured at the bottom region of unclean sections of the heat exchanger test tube.

Abstract: A radiometer is described which coherently detects the thickness of oil films on water by converting continuous-frequency microwave or millimeter-wave brightness temperature versus frequency measurements from the frequency/wavenumber domain to the oil-film-thickness domain (received power versus film thickness) using Fourier-transform signal processing.

Abstract: With an infrared radiator, the surface temperature of which is kept constant during measurement, a measuring area on a material surface is thermally irradiated with oblique incidence of the rays. The temperature of the reflected thermal radiation is measured by an infrared thermometer, which is arranged above the measuring area in such a way that the reflected radiation falls into the area of coverage of the infrared thermometer. The entire measuring area of the material surface which lies in the field of coverage of the infrared thermometer must be thermally irradiated. The measured temperature variation of the reflected radiation in dependence on the surface condition of the material is stored in a comparison device. A set value for the desired surface condition is fed to this comparison device.

Abstract: A method for the quantitative and qualitative evaluation of a nonuniform interface between a layer and a substrate is disclosed wherein thermal excitation is provided by irradiating the layer and thermal relaxation responsive to this thermal excitation is measured. The measured thermal relaxation is compared to the expected values, obtained from a model derived for the quantitative description of the process of thermal relaxation. The fraction of the deteriorated area of the interface is obtained from the portion of the thermal relaxation which diverges from the expected values.

Abstract: A method and apparatus is used to determine the thickness of a layer deposited on a specimen. For example, the thickness of a layer of polycrystalline may be measured as it is deposited over silicon oxide on a silicon wafer. The intensity of radiation emission at the top of the silicon wafer is detected. The temperature of the silicon wafer is measured and the variation in the intensity of radiation emission due to variation of the temperature is subtracted from the intensity of radiation emission detected at the top of the silicon wafer. The resultant signal is used to calculate the thickness of the polycrystalline silicon layer.

Abstract: This invention provides a sensing system for measuring a specific value such as the thickness, thermal conductivity, or the like of a substance to be measured by utilizing a change in thermal resistance with a simple arrangement. A sensor has a temperature difference setting thin film (202) and a temperature difference detection thin film (203) formed on a substrate (201) made of a thermally poor conductor, converts a change in temperature difference of the substrate (201) before and after a substance (200) to be measured is thermally coupled to the substrate into a change in thermal resistance of the substrate (201), and outputs the change in thermal resistance as a temperature difference information signal for calculating a desired specific value of the substance to be measured.

Abstract: This invention is a method for evaluating the type, extent, and threshold of fouling in a heat exchanger test tube by using a reference test block to measure a reference thermal relaxation time at a guaranteed clean reference section of a heat exchanger test tube and comparing the reference thermal relaxation time with thermal relaxation times measured at unclean sections of the heat exchanger test tube.

Abstract: An apparatus is disclosed for evaluating thermal and electrical characteristics of a sample. An intensity modulated pump beam is focused onto the surface of a sample at one spot. A non-modulated probe beam is focused onto the sample at a second spot, spaced laterally and vertically from the first spot. The distance between the two spots is at least two microns. The modulated power of the reflected probe beam that is in phase with the pump beam modulation frequency is monitored to provide information about the characteristics of the sample. The apparatus is particularly useful in evaluating the integrity of metal lines and vias in a semiconductor sample.

Abstract: A monitor for measuring heat transfer resistance comprising a housing and one or more test block assemblies, each test block assembly includes a movable test block enclosed on two sides by parallel side supports and attached by a spring to a spring support. Each test block assembly is attached to the housing. The spring urges the movable test block away from the spring support. Additionally, the movable test block will contain a heater, a thermometer, or both the heater and a thermometer.

Abstract: The thickness of a thin film on a substrate surface is determined by measuring its emissivity and temperature with a non-contact optical technique and then calculating the film thickness from these measurements. The thickness of the film can be determined by this technique in situ, while it is being formed and substantially in real time, thus allowing the measurement to control the film forming process. This has application to controlling the formation of dielectric and other material layers on a semiconductor substrate in the course of manufacturing electornic integrate circuits, including automatically terminating the process at its endpoint when the layer has reached a desired thickness.

Abstract: A process, apparatus and heat microscope for testing the properties of materials by the photothermal effect includes generating a laser beam with a laser light source integrated into a portable measuring head, emitting the laser beam toward a region of a surface of a material sample to be tested, and focussing the laser beam to a desired measurement point diameter at a target light spot with optics at an end toward the laser beam, for absorbing a proportion of the amount of light energy with irradiated volume elements of the material sample and emitting infrared light signals from the surface of the volume elements and volume elements adjacent thereto. The emitted IR light signals are conducted to an optical decoupling element for conducting the emited IR light signals further and largely suppressing components of the laser beam reflected at the surface of the sample.

Abstract: A system for non-destructively determining the thickness of a coating on a metal substrate includes using a first probe to locally heat the coating so as to establish a temperature gradient therein. The probe is configured so as to also provide electrical contact to the coating surface. This first probe is formed from a material having high thermal conductivity, and is at least partially plated with a material having high resistance to oxidation. Preferably, the probe plating material is chosen to also have high resistance to mechanical wear. The testing system also includes an electrical power supply for controllably heating the first probe in order to maintain the temperature thereof at a constant predetermined value. A second probe provides an electrical return contact in order to form a circuit for measuring the thermoelectric voltage between the two probes. This thermoelectric voltage may be conveniently measured by an AC amplification circuit.

Abstract: A method and apparatus for indirectly measuring the solid-liquid interface equilibrium temperature dynamically excites the heat flux flowing through a coldfinger arrangement followed by a statistical estimation of the interface temperature, solid layer heat conductivity and thickness ratio, bulk liquid temperature and thermal heat transfer coefficient. The coldfinger includes a pair of substantially concentric and substantially cylindrical members arranged one within another so as to have an outer member and a venturi-shaped inner member and a space therebetween. The members are arranged such that a gas flows through the inner member and a space between the inner and outer members of the coldfinger and then exits the coldfinger arrangement.

Abstract: A method of assessing the depth to which a crack extends below the surface of an object, or the thickness of a ligament (12) covering a crack (14), in which a thermal imager )26) is used to obtain a surface temperature profile along a line extending across the crack or ligament as heat is flowing across the surface and through the ligament. There is a steep drop in temperature across the crack or ligament, and the size of this drop at a predetermined time after the start of the heat flow may be simply related to the crack depth or ligament thickness.

Abstract: In the present invention, a discrete region of the TBC is heated, as by applying a controlled quantity of laser energy onto the region for a time interval. Then, the radiant thermal energy of a region outside the laser strike region is measured at a predetermined time following the termination of the laser pulse. The intensity of this measured radiant energy is then compared with the radiant intensities which have been experimentally obtained from known thickness specimens and the thickness is inferred therefrom.

Abstract: A scanning system including a source mounted on one side of a moving web and a detector on the other, and means for monitoring changes in the air temperature in the air gaps between the moving web and, respectively, the sensor and detector. The monitoring means comprises a thin sheet of a relatively opaque and inert material having a low thermal capacity and a low thermal conductivity, mounted closely adjacent one of the gaps and a thermopile mounted on the side of the sheet away from the gap for sensing the temperature of the sheet.In preferred embodiments in which the sheet is black polyester (e.g., "Mylar"), a sheet and thermopile are mounted on each of the sensor and detector housings, each sheet is mounted essentially coplanar with the inner side of the guide plate defining a respective air gap, and the respective thermopile is mounted on the side of its associated sheet opposite the gap.

Abstract: A probe having four spring-loaded tips contacts the backside of a semiconductor wafer in a processing machine. A current is induced across the outer tips and a voltage proportional to the sheet resistance of the wafer is measured across the inner tips. Wafer thickness is used to convert sheet resistance to bulk resistivity. Data on resistivity as a function of temperature is used to determine wafer temperature.

Abstract: The detection device comprises at least two electrically conductive elements (2, 4) arranged outside the refractory brick (1), at least one (4) of the two conductive elements from the rear face of the brick to a predetermined distance from the front face, in contact with the liquid metal, and the two conductive elements being connected to an electrical detection circuit (8, 9), in such a way that when the wear of the brick (1) reaches the end of the conductive element (4) the two conductive elements (2, 4) are put into contact with one another by the liquid metal, and this can be detected on the indicator instrument (9).The invention is used especially in steel metallurgy.

Abstract: The process consists in that two comparison tube sections (3; 4), which originate from a single condenser tube and of which one (3) is left in the corroded condition and/or the condition encrusted by mineral deposits and the other (4) is brought into the new condition by etching or other cleaning procedures, are conductively connected in series, and cooling water flows through them and they are heated from the outside in a condenser chamber in each case (1 and 2 respectively) by steam flows of equal power. The temperatures (t.sub.1, t.sub.2 and t.sub.3, t.sub.4 respectively) measured at the inlet and outlet positions of the comparison tube sections (3; 4), the measured values of the mass flow of cooling water (M.sub.w) and the steam temperatures (t.sub.f ; t.sub.b) and the heat flows (Q.sub.kf =Q.sub.kb) in the two condenser chambers (1 and 2 respectively) permit the determination of the thermal resistance (R.sub.

Abstract: The present invention is a system and method for determining the onset of scale in a pipeline carrying a petroleum liquid. A source provides electrical energy to a heating element in a housing adapted to fit in the pipeline. The housing also encloses a sensor for sensing the temperature of the petroleum liquid and providing a corresponding electrical signal. The housing is arranged with the heating element and the sensor in such a manner that there is heat transfer to and from the petroleum liquid so that as scale starts to coat the housing it affects the transfer of heat.

Abstract: The thermal deformation of an edge-restrained plate is expressed as a deflection of the plate out of its plane. Where the plate is used as a reference plane, the deformation of the plate can be quantitatively monitored and compensated for. In the case of a radiantly heated plate, the temperature gradient adjacent an edge of the plate is a linear function of the plate deformation. With convective cooling, the temperature drop from an initial condition relates linearly to deformation. Consequently, relatively simple temperature measurements will provide the necessary information. The invention has particular application to the roof of a military tank turret that is used as a reference plane for a gun sighting system.

Abstract: Materials to be tested for resistance of immersion swelling, drying shrinkage, thermal expansion and thermal contraction under light exposure are placed on a mount on a rotating shaft which immerses the sample in water, heats and dries it, and exposes it to light before cooling it by again immersing it in water. The samples may be simultaneously exposed to air pollutants by adding gases to a corrosion resistant chamber enclosing the rotating shaft. The chamber enclosing the rotating samples is composed of a lower tank base and a cover fitting into a liquid seal well on the tank base. The cover is fitted with fluorescent lights, an infrared heating strip, a thermocouple and a viewing port. A controller with indicator for the radiant heating strip and a speed control on the rotating shaft drive motor together with "run" and "pause" controls permit selection of the exposure cycles and their conditions.