Abstract: An optical system for exciting a temperature dependent phosphor with radiation and detecting independently emissions therefrom in optically isolable first and second wavelength ranges that gives an indication of the temperature of the phosphor. The optical system is carried by a heat-insulating housing disposed between a heat generating light source and the heat sensitive detectors. Dichroic mirrors are utilized to separate the two wavelength ranges emitted by the phosphor and to allow the sharing of a common optical path by three different radiation wavelength ranges without an undue loss of radiation intensity in any of the wavelength ranges. The light source may be of a helically shaped filament that is tilted with respect to an imaging optical axis so that the side of the helix is imaged with a minimum amount of the space between the turns showing, thereby maximizing the optical energy imaged from the light source.

Abstract: A critical temperature indicator is provided utilizing the volume reduction characteristics of organic compounds as they undergo a change from the liquid state to the solid state. The bulb and a portion of the capillary tube of a thermometer-like structure contains a colorless organic compound. Another organic compound saturated with a dye, which compound has a solidification temperature lower than that of the colorless compound and which is miscible with the colorless compound, is located in the capillary tube and separated from the colorless compound by a solid, movable plug or a liquid which is immiscible with either the colorless or the dyed compound. The volume of the colorless compound upon solidification is less than the volume of the bulb so that the separating plug or liquid and at least a portion of the dyed compound are drawn into the bulb upon solidification. The dyed compound then mixes with the colorless compound to provide a visual indication that the colorless compound has solidified.

Abstract: A critical temperature indicator is provided utilizing the volume reduction characteristics of organic compounds as they undergo a change from the liquid state to the solid state. A capillary tube sealed at one end contains a first organic compound adjacent the closed end and a second colored organic compound which has a solidification temperature lower than that of the first compound and which is separated from the first compound by a liquid which is immiscible with either the first or the second compounds. The separating liquid also has a solidification temperature lower than that of the first compound. A colorless or white porous plug is located within the separating liquid and frictionally engages the tube to prevent movement of the plug with respect to the tube.

Abstract: A liquid melt becomes converted to crystalline form at a particular temperature either spontaneously or when artificially nucleated. The liquid releases heat at crystallization. If the liquid is in a supercooled state when it begins to crystallize, its temperature will rise from the particular temperature at which it is nucleated.Another liquid material is mixed with the liquid to be crystallized. The liquid additive has properties of forming a metastable solid together with the crystallizing material. When the liquid additive exsolves, the crystalline aggregate is weakened and is easily decomposed into fragments of small size. The liquid additive materials may include monohydric alcohols, diols and triols. The liquid additive material may be included in the liquid to be crystallized, in small amounts, amounts to two percent (2%) to five percent (5%) being typical.

Abstract: A technique of temperature measurement wherein an object or environment to be measured is provided with a phosphor material layer that emits at least two optically isolatable wavelength ranges whose intensity ratio depends upon the object or environment temperature, the emitted radiation being brought to a detector by an optical system that may include an optical fiber. Several specific applications of this technique are disclosed, such as temperature monitoring of electrical equipment and industrial processing, medical temperature instrumentation including the use of disposable elements that contain a small quantity of the temperature dependent phosphor, special and multiple probes, the use of liquid phosphors, and a phosphor paint for monitoring surface temperatures.

Abstract: A thermometry system utilizes the thermally sensitive time dependent emission properties of luminescent materials. In one embodiment the system includes a probe constructed with an optic fiber bundle for conducting light both toward and away from the temperature sensitive luminescent element located at one end of the optic fiber bundle, a source for transient and/or modulated excitation of the temperature sensitive element, and a light responsive detection element located at the output end of the optic fiber bundle for detecting the transient and/or modulated light emissions by the luminescent temperature sensitive element. The emission signal received by the light responsive detector can be analyzed in a well defined manner to determine the temperature of the luminescent element and of any materials in thermal equilibrium with the luminescent material.