Abstract: The substance detection device comprises a transparent element and a light source for transmitting light through the transparent element onto a polished surface of the element. A pair of photodetectors are positioned for detecting intensity of light reflected from the polished surface and a circuit is provided for determining a difference in detected reflected light intensity on the photodetectors to determine a change in the critical angle of an optical interface at the polished surface.

Abstract: The invention is a temperature sensor which uses the variation in the critical angle between two optically transparent media, at least one of which has an index of refraction variable as a function of temperature, to variably refract and reflect portions of a spectrum incident on the junction of the media at angles less than and greater than the critical angle to produce an optical signal variable as a function of temperature.

Abstract: A prism has at least two optical planes and one of the planes is a boundary plane with mixed fuel. On one of two planes, a light emitting element is mounted and illuminates light to the boundary plane through the prism. A light receiving element receives light reflected from the boundary plane and converts the reflected light into electrical signals. Then a detector modifies the electrical signals from the light emitting element according to the detecting result and outputs them as detecting signals representative of the fuel mixture ratio. The temperature of the mixed fuel may be detected by a temperature sensor in which case the electrical signals are also modified to compensate for temperature changes of the mixed fuel.

Abstract: A blood glucose monitor which is particularly applicable for use as an implant for controlling an insulin pump, or as a portable device for use by a diabetic for home blood glucose monitoring. The glucose monitor measures the glucose level of blood by utilizing a refractometer which measures the index of refraction of blood adjacent to an interface with a transparent surface of the refractometer, by directing light at the interface to measure the index of refraction of the blood by the amount of radiation reflected by the interface, particularly light incident near the critical angle. In a preferred embodiment, polarized light is directed against an interface in an implant between a transparent material and the blood. As the glucose concentration in the blood changes, its index of refraction changes, as does the intensity of light reflected from the interface.

Abstract: The surface of a cellular body which is flat except for a number of cavities is examined by placing a transparent light refracting medium against the surface and transmitting light through the medium toward its interface with the body surface at such an angle of incidence to the interface that light incident on the interface at the body surface is refracted into the body and light incident on the interface at the cavities is totally reflected internally of the medium and then outwardly thereof. The reflected light produces an image having readily distinguishable zones of lightness and darkness indicative of the cavities and body material, respectively. The image is displayed in such manner as to enable either of the relatively dark and light zones to be counted. An optical coupling liquid is interposed between the body surface and the refracting medium to compensate for small gaps or irregularities in the body surface.

Abstract: An index of refraction sensor utilizing a sensor face inclined at the nominal critical angle of an incident beam, refracts or reflects this incident radiation depending upon the wavelength of that radiation and the index of refraction external to it. The refraction sensor apparatus includes a broadband radiant energy source, a radiant energy guidance and collimating means, a prism sensing element interposed in the radiant energy guide, and a detector for continuously detecting the spectral intensities of the broadband radiant energy reflected by the prism sensing element. Advantageously, a single mode optical fiber may be used as the radiant energy guidance and collimating means for directing the broadband radiant energy to the prism and a multimode optical fiber may be used for returning the reflected radiant energy to the detector.

Abstract: A sensor for detecting a light-transmissible foreign object, such as a raindrop, attached on a transparent body, such as a windowglass of a vehicle includes a light source, a light receiving unit disposed on the inside of the transparent body, and a prism fixedly attached on the transparent body on the inside thereof and arranged in a manner so that the light emitted toward the transparent body from the light source is caused to advance through the prism to reach the light receiving unit and that the quantity of light received by the light receiving unit changes when a light-transmissible foreign object attaches on the outside of the transparent body. The prism includes a restriction surface for preventing external light which enters the prism through the transparent body from coming into the light receiving unit.

Abstract: An automatic refractometer comprising a photosensitive device having a relatively narrow dynamic range in the form of a linear scanned array including a plurality of photoelectric elements each providing an output pulse during a scan and the amplitude of each pulse being determined by the amount of illumination of the corresponding element by incident light, an optical system for directing light onto the array in a manner such that the particular photoelectric elements of the array which are illuminated by the light are determined by the index of refraction of a light transmitting substance placed in operative association with the optical system, a circuit for converting signals from the array into digital signals containing information as to the amplitudes of the signals from the array, a digital processing circuit for storing respective signals from reference and sample substances placed in operative association with the optical system and for computing the index of refraction of the sample substance by mea

Abstract: A radiological measuring instrument including an angularly variable radiation sensitive structure comprised of two blocks of material having a different index of refraction with one of the materials comprising a radiochromic substance whose refractive index changes through anomolous dispersion as a result of being exposed to radiation. The ratio of the two indices of refraction is selected to be close to unity, with the radiation sensitive structure being pivotally adjusted so that light is directed into one end of the block comprising a material having the greater index of refraction. This element, moreover, is selected to be clear and transparent with the incident angle being close to the critical angle where total reflection of all incident light occurs. A portion of the incident light is furthermore projected through the clear transparent block without reflection, with the two beams emerging from the other end of the block, where they are detected.

Abstract: The invention relates to a measuring window for a process refractometer. Process refractometers are commonly used in the industry for continuous measurement of the concentration of a solution. The wall of the refractometer facing the process solution is provided with a window which must satisfy the requirement that the passage of light rays satisfies certain criteria, that the sealing is reliable, that the fastening is firm and that the wall facing the process and the window form a planar surface. The transparent portion of the window according to the invention comprises a roof prism embedded in a V-shaped groove in the process wall. Each wall of the V-groove is provided with a sealing abutting against the prism, and the third side of the prism forms a continuous plane with the process wall.

Abstract: An optical transducer that uses a prism for the purpose of determining a load applied thereto which may be used to find the weight of an object. In accordance with known optical principals, when a load is applied to a material such as plastic, glass, crystal and the like, its index of refraction changes. By measuring the change of intensity of light internally reflected from a prism made of such material, the magnitude of a load applied thereto can be determined.

Abstract: Refractometer for measuring the refractive index of a medium (2), using the limiting angle method. A source (4) illuminates a source slit (5) which has as its image with respect to an optical system (S) one of the parallel and regularly spaced slits (5') of a grille (6) fixed perpendicular to the optical axis each of the slits (5') corresponding to an angle of incidence of the optical beam on a prism (3). Turning of a rhombohedron causes the image (5') of the source slit (5) on the grille (6) to be successively on each of the slits (5') of the grille (6). The pupil (L.sub.1), located in the plane of the source, is conjugate with the exit face (8) of the prism (3) and remains stationary when the image (5') of the source slit (5) is moved over the grille (6).

Abstract: The device comprises two optical probes (51 and 52) consisting of a light conducting body which are designed to be immersed in the liquid by an intermediate section (53, 54) of the body, two light sources (60, 70) illuminating an extremity respectively of one (58) and of the other (68) body of the probes, two photoelectric transducers (61 and 72) located at the other extremity respectively of the first (58) and of the second (68) body of the probes, a member (73) which divides the signals originating from these transistors and a member (74) for the display of the resulting signal originating from that divider member.

Abstract: An optical coupling device wherein at least two light conductors are coupled through the intermediary of a transparent block in the shape of a half-ellipsoid on whose foci converge the end sections of the two light conductors. A light beam emerging from one conductor is reflected and transforms itself into a beam converging on the end of the second conductor. A slot permits the introduction of a liquid-crystal attenuating device connected to an alternating voltage source.

Abstract: An optical instrument for measuring the specific gravity of a solution, particularly the specific gravity of the acid in a lead acid battery, which incudes a base part and a transparent member, the transparent member including an incident light surface and reflector. The instrument further includes a light source arranged in the base part of the transparent member which is capable of radiating a straight-lined ray into the transparent member parallel to the axis of the member, and a photosensitive element for receiving light reflected by the incident light surface and the reflector. During use the instrument is positioned such that the transparent member is in contact with the solution whose specific gravity is to be measured.

Abstract: An immersion-type refractometric device for measuring the concentration of solutions including a probe having a curved measuring surface on the immersible tip. A light source directs a diverging light beam internally through the probe body toward the measuring surface. In one embodiment, light reflected from the measuring surface is received by a light-reflecting surface on the probe tip and directed through the probe body toward a photosensitive element connected to a measuring circuit which provides an output signal indicative of solution concentration. In another embodiment, the photosensitive element is located in the probe tip and receives reflected light directly from the measuring surface.

Abstract: A refractometric densitometer includes a first packing element and a first gasket disposed at one side of a glass element and a second packing element and a second gasket disposed at the other side of the glass element. A groove for passage of a reference material and a groove for passage of a sample are respectively formed in the first and second packing elements. An inlet pipe and an outlet pipe are formed in the first and second gaskets for passing the reference material or the sample to the grooves. The outlet pipe of the first gasket is connected to the inlet pipe of the second gasket. Multiple reflection is imparted to an incident light from the part of the glass element between the faced surfaces of the glass element contacting the first and second packing elements.

Abstract: An apparatus for continuous measurements of the density of variegated liquids, utilizing the angular displacement of the limiting angle at total reflection. Among other purposes the apparatus is useful for measurements of the acid concentration of liquids, such as in a storage battery in a motor vehicle to determine the state of charge of the battery. The apparatus comprises a light rod, in which the end to be immersed in the liquid is provided with a measuring surface and preferably also with a deflecting surface, a light source emitting a bundle of rays into the rod toward the measuring surface at a given divergent angle and a light-sensitive element positioned in the path of rays.