Abstract:
A purging air flow system for passing air over a lens to keep it clean and free from particulate contaminants and also for providing a positive flow of air away from the lens has baffles which cause a flow across the lens that is not symmetrical to avoid a dead air or stagnation zone in the center of the lens. The air supply used for such purging is controlled adequately so the flow changes direction and particles are removed from the main flow of purge air by inertial separation prior to the time the air contacts the lens. Such air entrained particles might otherwise deposit on the lens. A flow control orifice also may provide a secondary flow to carry the particles separated from the main flow out of the flow passageway.
Abstract:
An electron energy beam (28) discontinuously scans a sample (32) and at each scan position produces a thermal wave in the sample, there being infrared radiation emitted from the thermal wave. All of the infrared radiation emitted from the heated areas of the sample is collected by an ellipsoidal collector (34) and directed by reflection to an infrared detector (44), the sample and detector being at the foci of the collector (34), to give a two-dimensional image of the sample. A computer system (52) is used to control data acquisition, storage, processing and image display, and also modulation and scanning of the beam (28). Surface, on the surface, and sub-surface structure of the sample can be detected, for example to reveal defects, or surface particles.
Abstract:
A clinical thermometer is described, based on the measurement of the infrared radiation emitted by the patient, in which the body temperature of the patient is obtained in a non-invasive way and (normally) without any contact between the thermometer and the patient. During measurement of the temperature, the thermometer (1) is put at a preset distance (d) from the body of the patient, a distance which is normally determined by an optical aiming system consisting of two converging rays of light (5). A thermometer according to the invention may be used to obtain the temperature of the patient also by contact.
Abstract:
A light detector is disclosed for measuring the temperature of anobject (10). The light detector includes a lens assembly (20) for accepting light emitted from the object, an aperture (30), and a mirror (40) for reflecting the infrared energy of the object into a fiber optic cable (76). The fiber optic cable is connected toa depolarizing element (80) to which pressure is externally applied. The depolarization element relays the infrared energy into a detection portion and a signal processing portion for calculation temperature. Before the infrared light enters the fiber optic cable, a chopper (100), controlled by a driving circuit (300), chops the infrared energy reflected by the mirror.
Abstract:
An infra-red radiation detector comprises a pyroelectric detector element (1) in an hermetically sealed housing (9,20). The housing comprises a base (9) and cover (20) with an aperture (10). A Fresnel lens (18) for example made of polyethylene transmissive in the 8-14µm wavelength range is fastened over the aperture on the inside of the cover for condensing the radiation to be detected onto the detector element. In one example the Fresnel lens is held fast against a flange (17) surrounding the aperture for example by a push-fit ring (21) see Figure 1). Alternatively the Fresnel lens is glued to a silicon window (25) which in turn is fastened to the flange (17) over the aperture (10) (see Figure 2). The Fresnel lens thus forms an integral part of the detector housing avoiding the need for external mirrors or lenses.
Abstract:
The system relates to a telescope having optics and a scanning head which images a two-dimensional field of view point by point on to a localised thermal sensor. An aperture stop is mounted within the telescope housing and at least part of it is within the field of view of the sensor. The temperature of the stop is controlled by means of Peltier thermo-electric modules so that it corresponds to the average temperature of the external field of view. This prevents halation or blooming which would result from extreme temperature contrasts. The vignetting which occurs when the aperture stop is within the field of view gives an increased magnification for a given size of objective optics, and the benefits outweigh the corresponding reduction in thermal sensitivity.
Abstract:
Automatic material identification is achieved using infrared thermometry. A focused beam (31) of high flux energy is passed through a dichroic beam-splitter (5) to remove visible light with the remaining infrared energy directed to the surface (7) of the material to be identified. An infrared thermometer sensor (15) is positioned to sense the magnitude of the energy reflected from the material surface (7) with the magnitude of the reflected energy being indicative of the type of material reflecting such energy. Control apparatus (17) is employed to provide control signals as a function of the type of material identified such that automatic process operations may be effected in accordance therewith.
Abstract:
A non-contact temperature measuring system comprising a dual-reference body structure (5) is used to measure the temperature of a moving object (15). The moving object (15) is passed by first (20) and second (30) reference bodies having a same form factor with respect to the object (15). Each of the reference bodies (20, 30) has a heat flow sensor (40, 50) embedded at the end of a cavity (43, 53) formed in the reference body (20, 30) such that the heat flow sensor (40, 50) primarily responds to radiation heat flow generated by a temperature differential between the object (15) and its respective reference body (40, 50). With the reference bodies (20, 30) thermally isolated and maintained at different temperatures by heaters (60, 90) embedded in the reference bodies (20, 30), and their respective heat flow sensors (40, 50) properly calibrated, the temperature of the object (15) is calculated by applying the Stefan-Boltzman law.
Abstract:
A miniature passive infrared motion detector contains an optical system, a pyroelectric polymer film and an electronic circuit. The optical system is made of a curved Fresnel lens (3) and an elongated wave guide having reflective inner surfaces (1, 4). This affords a very wide field of view by the optical system with the energy (9) of an intruder, for example, focused to a small point on the polymer film (8) which is also curved with the same radius as the lens (3) and has two interdigitized electrodes (6, 7) on the rear surface and one uniform electrode (33) on the front surface. The front electrode (33) is covered with infrared absorbent material. The electronic circuit contains a differential amplifier (14) and a threshold network (22).
Abstract:
A light guiding unit comprises coaxially located light forming (1) and light transmitting (2) rods, made of a transparent refractory corrosion resistant material, for example, synthetic corundum. The length of the rod (1) is equal to the thickness t s of a metallized layer of a lining (4) whereas the length of the rod (2) is not less than the thickness t s of the other part of the lining (4). The rods (1) and (2) are connected to each other through a protecting bushing (7), made of a material which is plastic at the working temperature of the lining (4), and are placed inside a tube (3). The tube (3) is filled along the rod (1) with a refractory material (8) the sintering point of which is not higher than that of the lining (4) whereas its resistance against the action of the melt products is the same as that of the lining (4). At the working temperature of the lining (4) the material (8) has essentially the same linear expansion coefficient as that of the rods (1) and (2) and forms a viscous mass which is not alloyable with the rod (1). The silicon oxide powder may be used as the material (8). The tube (3) is eilled, along the rod (2) with a refractory material (9) the sintering point of which is above the working temperature of the lining (4) and than its sintering point, that refractory material being, in particular, the corundum powder.