Abstract: A gas detection system, comprising: a humidity measuring apparatus that measures humidity; a transmitting apparatus that includes a light source which emits an optical signal of a plurality of wavelengths; and a receiving apparatus including: a light detection part that receives the optical signal from the transmitting apparatus; a discrimination part that determines whether or not condensation exists in at least one region of regions where the optical signal passes, based on the humidity measured by the humidity measuring apparatus and a light intensity of the optical signal received by the light detection part.

Abstract: A chilled mirror hygrometer may comprise a thermoelectric module, a polished mirror surface, two light emitting diodes, and a single photo-transistor or optical detector. A software controller may be employed to rapidly alternate between illuminating the two light emitting diodes. The software controller may allow the single photo-transistor or optical detector to rapidly alternate between observing the light from the first light emitting diode or the second light emitting diode. The chilled mirror hygrometer may further comprise a wand portion and an electrical housing.

Abstract: An electronic device includes at least one electronic component, a gradient heat-flux sensor GHFS based on thermoelectric anisotropy and conducting heat generated by the electronic component, and a controller adapted to manage electrical current of the electronic component at least partly on the basis of an electrical control signal generated by the gradient heat-flux sensor and proportional to a heat-flux through the gradient heat-flux sensor. Therefore, the electrical current and thereby also the heat generation of the electronic component are managed directly on the basis of the heat-flux generated by the electronic component. Thus, the electrical current can be managed without a need for voltage and current measurements which may be challenging to be carried out with a sufficient bandwidth especially when the switching frequency of the electronic component is on a range from hundreds of kHz to few MHz.

Abstract: Embodiments related to moisture abatement during a heating operation of a climate control system are disclosed. In some embodiments, the climate control system includes a thermoelectric device (TED) or other thermal condition device having a hot side and a cold side. In certain embodiments, the thermal conditioning device is operated (e.g., by a processor or a condensate switch) to inhibit or prevent the occurrence of condensation, and/or to abate condensation that has already occurred, on the cold side of the thermal conditioning device during the heating operation.

Abstract: Disclosed herein is a switching board having switching elements for temperature measurement mounted on a printed circuit board (PCB) having a circuit electrically connected to a unit cell constituting a battery module, the switching board including an upper board having a pair of switching elements, a temperature detection element, and one or more vertical through holes, the switching elements being electrically connected to the circuit, the temperature detection element and the vertical through holes being disposed between the switching elements, and a lower board having a heating pad at a position corresponding to the vertical through holes and the temperature detection element.

Abstract: A therapeutic laser with a source of pulsed electromagnetic radiation, a control device for controlling the intensity and/or the duration of the therapeutic laser applied to the tissue, and a detection device for detecting optoacoustic signals triggered by irradiating the living tissue with the pulsed electromagnetic radiation. The therapeutic laser is characterized by an evaluation device that acts on the control device and is used for calculating a degree of quality B(t) from the optoacoustic signals detected by the detection device for individual laser pulses applied to a predetermined laser spot and determining a fit function f(t) at a predetermined point in time ?t1, the fit function f(t) approximating the mean curve of B(t) for 0?t??t1. The intensity and/or the irradiation time of the therapeutic laser is defined by the parameters for the predetermined laser spot, the parameters being determined for the fit function f(t).

Abstract: An apparatus includes a temperature detector coupled to a conductive layer of an electrophoretic display device. The temperature detector is operable to measure a leakage current that is responsive to a temperature associated with the electrophoretic device and determine the temperature associated with the electrophoretic device based at least in part on the measured leakage current.

Abstract: A sensing system is configured to detect physical parameters of a fluid sample. In particular, the sensing system is configured to detect the dew point of the fluid by reducing temperature of a sensing medium and detecting the fluid condensate on a sensing surface by directing light from a light source to the sensing surface and detecting the light reflected off the sensing surface onto a light detector. The light source and the light detector are on the opposite side of the sensing medium from the sensing surface.

Abstract: An apparatus and method for determining at least one of the temperatures at which a petroleum product will manifest delayed haze and the temperature at which haze will not exist in the product is provided. The apparatus comprises a container for holding a sample of the product, a light source, light detector, heaters and coolers combined with microprocessor means for storing and analyzing at least one of light transmitted or scattered by the sample. Measurements are useful in determining the haze properties of the product and also for controlling a dehazing process to meet target haze properties.

Abstract: A method for improved handling of a blended fuel includes obtaining a sample of the blended fuel from a storage tank; cooling the same until the sample separates into phases; and determining a risk that the fuel in the storage tank will separate based on the cooling step. An apparatus for assessing the risk of phase separation of a blended fuel includes a test cavity for holding a sample of the blended fuel from a storage tank; a heat transfer device for cooling the sample in the test cavity; and at least one sensor for indicating when the sample in the test cavity has separated into phases.

Abstract: The invention relates to a method and a sensor for determining the hydrocarbon dew point in a gas, in particular in a gaseous fuel. According to the invention a roughened condensation surface is provided on a planar measurement surface of a transparent body. Light is shone onto the roughened condensation surface through the transparent body and the intensity of the light reflected back into the transparent body is measured. The hydrocarbon dew point temperature can be inferred from changes in the intensity of the light which is reflected back when heating or cooling the condensation surface.

Abstract: Cloud point monitoring systems for determining a cloud point temperature value for diesel fuel are provided. In one exemplary embodiment, a cloud point monitoring system receives diesel fuel in the tubular conduit and propagates a sound wave through the diesel fuel. The cloud point monitoring system further determines a cloud point temperature value indicative of a cloud point of the diesel fuel based on a phase shift of the sound wave propagating through the diesel fuel.

Abstract: A thermally managed enclosure for batteries in a motor vehicle or other machinery includes a cradle of thermally conductive material for containing a battery. The cradle having a bottom wall and side walls closely fitted to and in contact with the battery, to maintain the battery in a stable position. The bottom wall of the cradle has a passageway trough containing a tube for flowing heating or cooling fluid therethrough, to control the optimal operating temperature of the battery. The passageway trough is preferably filled with a thermally conductive fill surrounding said tube. When two or more batteries are required, an array of adjacent cradles are provided in a monocoque tray formed by bonding or welding the multiple cradles at their adjacent sides. These cradles are optionally connected by linearly extending rods in the cradles.

Abstract: The invention relates to a method and a sensor for determining the hydrocarbon dew point in a gas, in particular in a gaseous fuel. According to the invention a roughened condensation surface is provided on a planar measurement surface of a transparent body. Light is shone onto the roughened condensation surface through the transparent body and the intensity of the light reflected back into the transparent body is measured. The hydrocarbon dew point temperature can be inferred from changes in the intensity of the light which is reflected back when heating or cooling the condensation surface.

Abstract: In a thermoelectric device, a thermoelectric element has one surface on a low temperature side and the other surface on a high temperature side. A member is attached to at least one of the low- and high-temperature-side surfaces of the thermoelectric element. A temperature detection element is provided between the member and the surface of the thermoelectric element to which the member is attached. A mirror surface state detection device is also disclosed.

Abstract: A new method and apparatus is described for measurement of the dew point, and thus the vapor pressure of various gases and gas mixtures. In this method an optical element which is exposed to a gas atmosphere is cooled while its temperature is being monitored. At the same time an optical signal is sent through the back of the optical element. The optical signal goes through internal reflections. As soon as dew forms on the surface of the element, the optical signal will exhibit selective absorption due to the interaction of the evanescent tail of the optical signal and based on the chemical nature of the condensate. This invention can also be used to characterize condensable content of gas mixtures. The method allows for the spectral characterization and determination of the condensed vapor. It offers several advantages over existing methods.

Abstract: A thermally managed enclosure for batteries in a motor vehicle or other machinery includes a cradle of thermally conductive material for containing a battery. The cradle having a bottom wall and side walls closely fitted to and in contact with the battery, to maintain the battery in a stable position. The bottom wall of the cradle has a passageway trough containing a tube for flowing heating or cooling fluid therethrough, to control the optimal operating temperature of the battery. The passageway trough is preferably filled with a thermally conductive fill surrounding said tube. When two or more batteries are required, an array of adjacent cradles are provided in a monocoque tray formed by bonding or welding the multiple cradles at their adjacent sides.

Abstract: The invention relates to a device for measuring quantities of heat while simultaneously measuring the evaporation kinetics and/or condensation kinetics of the most minute amounts of liquid in order to determine thermodynamic parameters. The aim of the invention is to determine low thermal outputs, which are absorbed or released by the sample, as well as small differences between thermal outputs with regard to a reference measurement of the same magnitude. To this end, a most minute amount of liquid is located inside a measuring chamber having a constant temperature and air humidity. At least one thermal sensor is provided for repeatedly measuring the thermal radiation emitted from the most minute amount of liquid. A measuring means serves to determine the time-dependent change in the most minute amount of liquid. A computer is assigned to the measuring chamber in order to register, display, evaluate and/or subsequently process the measured values.

Abstract: A cloud point monitoring device which includes thermal conductive surface, cooler, temperature sensor, detection volume, detection wall unit, fiber optic cables for transmitting light, lighter emitter, light detector, and a data acquisition and control unit. The cloud point monitoring device provides an instrument to accurately measure the cloud point of diesel fuel indicate the approximate level of crystallization in diesel fuel that has been chilled beyond its cloud point and indicate the approximate energy content of diesel fuel. The cloud point monitoring device design allows it to be made small enough to be mounted in a fuel system of a vehicle.

Abstract: A dew point hygrometer for determining the dew point of a gas in which a displaceable transparent film is in contact with the gas and forms a condensation surface. The film is placed on a temperature control device controlling its temperature and an optic fiber, emits light on the film and reflected light is detected in another optic fiber, the two optical fibers being positioned at an angle with respect to the film. Condensation formed on the film changes the light transmitted by the film which is periodically displaced so that a new uncontaminated regions are exposed to the light.

Abstract: A cloud point monitoring device which includes thermal conductive surface, cooler, temperature sensor, detection volume, detection wall unit, fiber optic cables for transmitting light, lighter emitter, light detector, and a data acquisition and control unit. The cloud point monitoring device provides an instrument to accurately measure the cloud point of diesel fuel indicate the approximate level of crystallization in diesel fuel that has been chilled beyond its cloud point and indicate the approximate energy content of diesel fuel. The cloud point monitoring device design allows it to be made small enough to be mounted in a fuel system of a vehicle.

Abstract: A fuel freezing point monitoring device to monitor the freezing point of onboard fuel, especially aircraft fuel. The fuel freezing point monitoring device is capable of monitoring the phase transition or fluidity of the fuel to determine the freezing point of the fuel. The fuel freezing point monitoring device eliminates the freezing point assumption of onboard fuel by actually measuring the freezing point of the fuel. The pilot will have knowledge of the approximate freezing point of the composite onboard fuel and will no longer need to assume a conservative fuel freezing point value. Together with the en-route fuel temperature information provided by existing aircraft sensors, the pilot will have the information to ensure a safe flight and to operate the aircraft efficiently.

Abstract: The melting point of a test substance is determined by placing it in a glass capillary tube within a metal block equipped with an electrical heater and temperature monitoring device. The temperature of the metal block and sample are gradually increased, often to temperatures that would damage electronic components. The output of a light emitting diode located a short distance from the metal block and away from the high temperature is coupled into a hollow tubing having highly reflective internal walls that carries the radiation to the glass capillary tube containing the test substance. A second hollow tube, also having highly reflective internal walls, is connected to a light detector that collects reflected radiation from the capillary tube. At the melting point of a solid, the light reflecting properties of the test substance decrease causing the light signal collected by the second reflective tube to decrease. The melt point is recorded as a change in the output voltage from the detector.

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: An apparatus and method for determining the crystallization point of high pressure fluids comprising brine are disclosed. The apparatus comprises a temperature probe and an optical fiber probe to determine the temperature of formation and dissolution of crystals during cooling and warming cycles. The apparatus further comprises a pressurization source, preferably a positive displacement pump or connection to a positive displacement pump for pressurizing the sample. The apparatus further preferably includes a jacket for circulating coolant or heat transfer fluid to facilitate cooling of the sample. The method of the invention uses the apparatus of the invention to determine crystallization point of fluid samples.

Abstract: A method and apparatus for high-throughput determination of phase change points of combinatorial libraries of metal alloys uses an infrared camera to monitor temperature-dependent changes in emissivity/reflectivity of the alloys. An infrared focal plane array monitors the emissivity/reflectivity changes over time, and the intensity of each heated member over time is correlated with temperature to detect the phase change points of the members.

Abstract: The apparatus for determining the dew-point and/or the content of vapor in the air, particularly for the use in radio sondes, comprises a dew-point mirror assembly, including a source of light, a reflector, a cooling element thermally coupled to the reflector, a temperature sensor for measuring the temperature of the reflector, and a detecting sensor for receiving the light emitted by the light source and reflected by the reflector. The detecting sensor is located in a temperature stabilized region of the apparatus and optically coupled to the reflector by means of a light wave conductor. The light source is an incandescent lamp. A sensor head is provided that receives the reflector, the cooling element, the light source, and the input end of the light wave conductor. The sensor head is heated by means of an active heating element.

Abstract: A method and apparatus is provided for monitoring and controlling the temperature at the heat producing portion of an electrical current carrying device without direct measurement at the heat producing site. An integrated circuit 22 is thermally attached to a plurality of heat dissipating paths; top side heat conduction path 24, bottom side heat conduction path 26, and board level heat conduction path 28. On one of the heat conduction paths exists a heat flow sensor. This sensor is comprised of an inner thermistor 32 and an outer thermistor 34. The measured heat flow is combined with a single point temperature measurement and the thermal conductivity between the heat source and the temperature measurement point to produce the temperature at the heat source. This temperature is monitored in order to keep the temperature of the electrical current carrying device below critical levels or within a specified range.

Abstract: A system and method for performing localized mechanothermal analysis with scanning probe microscopy (“MASM”) is disclosed. In a preferred embodiment an image of the surface or subsurface of a sample is created. A localized region of the sample is selected from the image. Using a scanning microscope, an active or passive thermal probe is positioned at the selected region. A temperature ramp is applied to the localized region. In addition, a dynamic or modulated stress or strain is applied to the localized region. Force data resulting from the applied temperature and stress or strain is collected and processed to produce a graph or fingerprint of the dynamic mechanical and/or calorimetric properties of the selected localized region.

Abstract: A fiber optic hygrometer apparatus and method for sensing and measuring the dew point of an atmosphere is disclosed that includes a controller for controlling the operation of the apparatus and a first optical fiber for transmitting light energy from a source of light energy to an optical core extending into the atmosphere being monitored. The optical core includes an end that is prepared as a reflecting surface, allowing the light energy reaching the optical core to be internally reflected back toward the source. A second optical fiber captures the light energy internally reflected from the optical core and conveys the captured light energy to a light energy detector. The light energy detector is arranged to output signals to the controller representing the magnitude of the light energy captured. A cooling device and a temperature-sensing device operationally connected to the controller are attached to the optical core.

Abstract: A device for use in vehicles with electric or hybrid drive for monitoring the air conditioning of a vehicle based on health and energy consumption readings. The device monitors the operation of the air conditioning to determine when differentials between outside and inside temperature are excessive, and/or inside atmospheric humidity is too low and/or air quality is poor. An occurrence of any of these conditions results in the system suggesting to the driver that he should interrupt travel to the desired destination. In addition, if necessary, the device performs a vehicle range estimate as a function of the selected air conditioning operation.

Abstract: A novel method for measuring a deposit point is provided, which makes it possible to quickly and accurately measure a cloud point. A test sample is irradiated at an angle of incidence .theta. with an incoming light beam which satisfies an expression .theta.<.theta..sub.2 while gradually cooling the test sample such as gas oil, and a totally reflected light beam from the test sample is detected for every temperature, provided that .theta..sub.2 represents a critical angle of total reflection of a deposit such as a paraffin component deposited when the test sample is cooled. The deposit point of the test sample is determined from a change in intensity of the totally reflected light beam with respect to the change in temperature. The light intensity distributions, detected by a sensor array at respective temperatures, are statistically processed to more accurately determine the deposit point.

Abstract: A method of determining the dew point or frost point of a gas containing a very small amount of water uses an optical dew point meter having a reflector mirror the temperature of which can be varied from room temperature to any point of -80.degree. C. or below, a device for contacting the reflector mirror with the gas to be measured, a light source for irradiating the reflector mirror with focused rays of light, and a detector for detecting the change in scattered light and/or reflected light due to the dew and/or frost condensed on the reflector mirror. The method gradually reduces the temperature of the reflector mirror, either before or while the reflector mirror and the gas contact, thereby condensing dew and/or frost on the reflector mirror. Following formation of dew and/or frost on the reflector mirror, the intensity of scattered light or reflected light is adjusted from a maximum value to a constant level, at a controlled temperature.

Abstract: A method of determining cloud points is provided which comprises: bringing a sample into contact with a high precision cloud point meter which includes a waveguide sensor of a total-reflection type connected to both incidence and emergence optical fibers and a cooling/heating means located in contact with the total-reflection type sensor to cool/heat it within a desired temperature range; cooling/heating the sample; and then determining the sample temperature at which total-reflection of light has taken place as the cloud point of the sample. The sensor includes a waveguide of a structure which consists of an incidence channel and an emergence channel formed on a substrate and which intersect along a detection surface with which a liquid whose cloud point is to be determined comes in contact.

Abstract: The invention relates to an apparatus for determining the frost point of a gas containing a very small amount of water. The apparatus comprises (I) compartment A made of a good heat conductor; (II) an inlet for the gas to be measured, which inlet is provided on compartment A; and (III) a heater for adjusting the temperature in compartment A, and a temperature sensor. The apparatus further comprises (IV) compartment B which is adjacent to compartment A. At least part of compartment B is made of a poor heat conductor. Further, the apparatus comprises (V) a hole at the interface between compartments A and B and (VI) a reflector mirror having a temperature sensor. The reflector mirror is provided on compartment B in such a way as to cover the hole is connected thermally to a freeze source in such a way that the temperature of the reflector mirror can be varied from room temperature to at least -80.degree. C.

Abstract: A cycling chilled mirror hygrometer is described wherein the mirror employed comprises a sapphire substrate having deposited thereon alternating layers of titanium dioxide and silicon dioxide. The surfaces resulting from the described technology yield a ten fold enhancement over the "theoretically pure" optical surface characteristics achieved with the prior art gold mirrors. Additionally, these devices have provided ideal surface characteristics for 350 degree optical triangulation, thereby permitting greater primary sensor sensitivity at low humidity levels (below -40 Cdp) and the elimination of long term "optical reflective gain" variations due to aging characteristics as compared with the conventional gold mirrors having impurities.

Abstract: A method of determining the dew point of a gas containing a very small amount of water using (1) a reflector mirror the temperature of which can be varied from room temperature down to at least -80.degree. C.; (2) a source of condensed rays of light for irradiating the reflector mirror; and (3) a light recovering device that detects changes in scattered light due to condensation on the reflector mirror by exposing the mirror to the gas. The method comprises cooling the mirror and detecting the temperature at which the scattered light has a maximum intensity; slowly raising the temperature and detecting the temperature at which the scattered light has a minimum intensity and repeating the cycle until the temperature at which the intensity is a maximum and the temperature at which the intensity is a minimum are almost the same.

Abstract: A method of cleaning a reflector mirror in an optical dew point meter that measures the dew point or frost point of a sample gas by a process including the steps of bringing the sample gas into contact with the reflector mirror whose temperature is variable, projecting condensed rays of light or laser light onto said reflector mirror, and detecting the change in the intensity of scattered light and/or reflected light on account of the dew or frost formed on said reflector mirror, characterized by bringing a CO.sub.2 gas or a CO.sub.2 containing gas into contact with the reflector while the latter is in a cooled state, thereby condensing CO.sub.2 on the surface of the reflector mirror, and the subsequent step of heating the reflector mirror to vaporize the CO.sub.2 is dischosed.

Abstract: A dew or frost point temperature hygrometer wherein a reflective surface, which is cooled by a cryogenic source and held at the dew or frost point temperature by a servo control, reflects light from a light source to a light detector. Very low concentrations of moisture or frost which condense on the reflective surface are measured very rapidly as a change in light reflected from that surface. No re-calibration is needed throughout its exceedingly wide moisture measurement range of from less than 1 part per billion to about 30 parts per thousand within a range of temperature from about -110.degree. C. to about 30.degree. C.

Abstract: A method and system for regulating the temperature of a hot melt ink wherein light reflected from a phase change material adjacent to the ink is detected, and a closed loop control signal proportional to the intensity of the reflected light is generated. The control signal is applied to a heater element for the ink and provides good temperature control thereof. In addition, the phase change material is used to generate an ink level indication signal which is also processed in a closed loop servo system in order to provide control over levels of the hot melt ink during operation of an ink jet printhead. In the embodiment of the present invention for controlling both ink temperature and ink levels within a pen body housing, there is provided a means and method for simultaneously sensing the liquid level and temperature at the solid/liquid interface within the pen body housing.

Abstract: A dew or frost point hygrometer wherein a reflective surface, which is cooled by a cryogenic source and held at the dew or frost point-temperature by a servo control, reflects light from a light source to a light detector. Very low concentrations of moisture or frost which condense on the reflective surface are measured very rapidly as a change in light reflected from that surface. No re-calibration is needed throughout its exceedingly wide moisture measurement range of from about 1 ppb to about 30 ppm within a temperature range of from about -110.degree. C. to about 30.degree. C.

Abstract: Infra-red light from an emitter is directed through a glass slide to an area on which a solid substance is located. Light reflected from the undersurface of the solid substance is received by a receiver. The substance is heated by a strip heater. When the substance changes state, the amount of reflected light arriving at the receiver varies, and information coming from an electronic thermometer records the temperature at which the change of state has occurred.

Abstract: A method and an apparatus for measuring dewpoint of different kinds of gases, is based on cooling the measured gas, with the help of cold gas, down to the dewpoint and then detecting the generated mist by optical sensors. The cooling gas is routed to a measurement area (7) from outside the process and the cooling gas is brought to an appropriate temperature below the dewpoint of the measured gas before being conducted to the measurement area (7). Mist generated during the cooling of the measured gas is detected by illuminating the measurement area (7) by a light emitting source (8) and measuring the light (2) scattered from the mist or light (3) penetrating through the mist with the help of a photodetector (9). The temperature of the measurement area is continuously monitored with temperature sensors (10) so that when the mist is detected, the temperature of the measurement area (7) at that instant corresponds to the dewpoint temperature of the measured gas.

Abstract: A method for determining the relative humidity of gaseous materials, preferably for determining the relative humidity of air in rooms, such as greenhouses, whereby, using psychrometric moisture measurement, the temperature of the stream of gas, the relative humidity of which is to be measured, is determined by means of temperature sensors. A gas stream acting upon a moistenable wet temperature sensor is cooled up to a cooling limit (wet-bulb point) and the wet bulb point temperature is determined. The relative humidity is ascertained using the measured temperature of the gas and the wet-bulb temperature.

Abstract: Apparatus for monitoring the cloud point of a liquid, or the temperature at which any light scattering phase occurs therein, comprising a light-proof and light-absorbing chamber, and a liquid sample-receiving receptacle within the chamber having a bottom formed by a non-light-scattering surface; this surface being in thermal contact with a heating or cooling device, such as a thermoelectric cooler, and with a temperature measurement device. The chamber can be opened to allow access to the receptacle so that sample liquid can be placed therein. A light beam source is located to direct a beam of light onto the surface at an incident angle so that light from the beam is reflected or absorbed by the surface. A light detector including a lens and an array of detection cells is arranged so as to detect scattered light which is produced when solid material forms in the liquid as it is cooled or disappears on heating.

Abstract: An improved method of and an apparatus for measuring a very low water content in a non-condensible gas which has a dew point in the range of from ordinary temperature to -80.degree. C. or less. The gas to be measured is pre-cooled to a temperature slightly higher than that of the dew point, and is then blown against a reflecting mirror whose surface is cooled down to the dew point temperature of the gas. A condensed light having high luminance is projected toward the reflecting mirror. When the gas is blown against the mirror and cooled down to the temperature of the dew point, thereof a dew or frost is formed on the mirror, and the amount of scattered light reflected from the mirror is increased by the dew or frost. This increase in scattered light is detected by a photodetector. A silicon wafer which is polished to have a surface precision of 1/4 or less that of the wavelength of the condensed light is employed as the mirror to enable measurement of dew points of -80.degree. C. or less.

Abstract: An elongated mirrored surface has a temperature gradient established thereacross. Condensation forms along the mirrored surface and the edge of the condensation next to the portion of the mirrored without condensation is where the dew point temperature exists. A scanning means is provided for locating this edge of the condensation. Temperature sensing means, located at the edge, measures the dew point temperature.

Abstract: The invention is directed to chemical compositions suitable for use in salt-solution transition temperature or hot mirror devices. It also provides methods of using these sensors (for the measurement of the humidity of gases) as well as the apparatus. The chemical composition which of itself senses the changes of water vapor pressure is birefringent at a first water vapor pressure and temperature, but non-birefringent at a second vapor pressure and temperature. The optical changes which accompany these phase changes may be amplified with polarizers. The means for heating the chemical composition can vary widely. Various thermometric devices can be used for temperature sensing. The accuracy required of the particular instrument model, the device's configuration, and the other components, selected for the particular system all affect the choice of thermometric device selected.

Abstract: The dew points of condensible hydrocarbon and water in a gas stream are determined independently in a single run by observing changes in intensity of light scattered from a mirror surface which is cooled to below both of the dew points. A decrease in intensity denotes the hydrocarbon dew point while an increase in intensity denotes the water dew point. The apparatus is simple and operates automatically. The mirror surface has a first polished and highly reflective portion and a second, roughened, less reflective portion. The intensity of scattered light is preferably monitored separately for each mirror portion.

Abstract: A method of measuring reliability of an information recording medium which comprises an information recording thin film. The method comprises the steps of heating said film at least once to its melting point, rapidly cooling said film after heating, measuring a transition temperature of said film after cooling, and comparing said transition temperature with a predetermined reference temperature.