Abstract: An improved intensity-encoded fiber optic sensor incorporating novel drift correction and filtering means is disclosed. The first embodiments of the invention relate to means for removing unwanted higher-order core and cladding modes from an intensity-encoded signal in an optical fiber using mode strippers and mode filters located strategically at various points in the sensing system. The second set of improvements in the invention relate to an improved technique for long-term temporal drift cancellation in a fiber optic pressure sensor by periodically applying pressure to the sensor tip in order to ascertain the measured voltage at which the sensor diaphragm contacts other elements of the sensor. This measured voltage is subtracted from an initial calibration voltage, and the result is applied to the measured signal as a constant correction term.

Abstract: An electronic tire pressure gauge has a tire valve stem receiver, a thin silicon square diaphragm with four diffused resistors configured in a full Wheatstone bridge as a pressure transducer, a voltage controlled oscillator, a comparator, a clock, a microprocessor with program memory, and a display. The comparator compares the stable transducer output for a given pressure with the voltage-controlled oscillator output, to yield a comparator pulse which goes high while the transducer signal is greater than the oscillator signal. The clock provides bus cycles used by the microprocessor for counting the duration of the high comparator pulse. Multiple high comparator pulses are compared, and the longest duration is selected and converted to a pressure value and displayed. Battery power is conserved by a power on/off algorithm.

Abstract: A method for quantifying glucose concentration in blood, body fluids, and other samples within, below and above the normal physiological range, which relies on non-radiative fluorescence resonance energy transfer, as well as devices useful in quantifying blood glucose concentration using the present method.

Abstract: A fiberoptic based sensor for patient care use. The sensor includes a catheter placed transcutaneously into a blood vessel which is connected to an external measuring head. A sensing tip of the catheter includes a pressure sensing element and an oxygen saturation measuring element. Features of the invention include novel tip designs, measuring head features, and approaches for enhancing measurement though correlation of the saturation and pressure readings.

Abstract: The invention is related to numerous improvements for fiber optic measuring systems, and principally those utilizing a deformable diaphragm for sensing pressure. One aspect of the invention is providing temperature compensation for diaphragm characteristics. Temperature measurement can be achieved by using a light signal having a wavelength distribution which overlaps the cut-off characteristics of a filter positioned at the fiber sensing end. Shifting in the cut-off characteristic in response to temperature modulates the intensity of the reflected back temperature compensation signal. In another approach, temperature is measured through its differential effect on light signals having different launching conditions. With either approach, the temperature measurement is used to calibrate the output of the pressure sensitive diaphragm.

Abstract: An improved intensity-encoded fiber optic sensor incorporating novel drift correction and filtering means is disclosed. The first embodiments of the invention relate to means for removing unwanted higher-order core and cladding modes from an intensity-encoded signal in an optical fiber using mode strippers and mode filters located strategically at various points in the sensing system. The second set of improvements in the invention relate to an improved technique for long-term temporal drift cancellation in a fiber optic pressure sensor by periodically applying pressure to the sensor tip in order to ascertain the measured voltage at which the sensor diaphragm contacts other elements of the sensor. This measured voltage is subtracted from an initial calibration voltage, and the result is applied to the measured signal as a constant correction term.

Abstract: A laser power control system is disclosed which detects the power of an emtted laser beam. The detection is preferably accomplished by splitting the beam using a beam splitter to form a detector laser beam which includes a limited portion of the beam. The beam is preferably split after polarization to obvate changes in detected power associated with polarization changes which can occur in the laser. The detector beam can be detected either continuously or intermittently, such as by using a chopping wheel which intermittently passes and interrupts the detector beam. The detected laser beam power signal is compared against a predetermined set point or preprogrammed time variable laser power profile thus allowing desired laser power to be achieved. The laser beam is also preferably equalized to achieve a more uniform cross-sectional laser power density.

Abstract: Radiation dosimeters and dosimeter badges. The dosimeter badges include first and second parts which are connected to join using a securement to produce a sealed area in which at least one dosimeter is held and protected. The badge parts are separated to expose the dosimeters to a stimulating laser beam used to read dose exposure information therefrom. The badge is constructed to allow automated disassembly and reassembly in a uniquely fitting relationship. An electronic memory is included to provide calibration and identification information used during reading of the dosimeter. Dosimeter mounts which reduce thermal heating requirements are shown. Dosimeter constructions and production methods using thin substrates and phosphor binder-layers applied thereto are also taught.

Abstract: Disclosed is a laser dosimeter reading apparatus having a controllable optical laser converter for providing multiple stimulating laser beams. The converter laser dosimeter reader can be used to stimulate or otherwise treat dosimeter elements to perform two or more distinct processes on a particular dosimeter element. Additionally, the convertible dosimeter reader can be used to read multiple different types of dosimeter elements contained on a single dosimeter badge, thereby allowing a badge to be read in a multi-stage reading operation in a single dosimeter reader which is preferably automated. The optical laser converter includes a converter block assembly which defines multiple optical pathways therethrough. The convert block assembly is movable between different positions to align the different optical pathways with an incoming laser beam.

Abstract: Disclosed is a radiation dosimeter reading apparatus designed to disassemble, reposition, read, and reasemble radiation dosimeter badges. The dosimeter reading apparatus includes a dosimeter badge chuck assembly which engages a dosimeter badge in an infeed dosimeter badge holder. The chuck assembly engages the dosimeter badge using a set of tamper element prongs which depress a tamper ring which forms part of the dosimeter badge. The depression of the badge tamper ring releases a locking ring which also forms part of the dosimeter badge. Once the locking ring is freed, then another set of prongs on the chuck assembly are rotated to route the locking ring of the badge and thereby release a disk-shaped dosimeter badge insert. The chuck assembly is further adapted to grasp the released insert by contracting the tamper element prongs inwardly against the perphery of the disk-shaped insert to hold the inset on the chuck assembly.

Abstract: Disclosed is a laser dosimeter reading apparatus having a controllable optical laser converter for providing multiple stimulating laser beams. The convertible laser dosimeter reader can be used to stimulate or otherwise treat dosimeter elements to perform two or more distinct processes on a particular dosimeter element. Additionally, the convertible dosimeter reader can be used to read multiple different types of dosimeter elements contained on a single dosimeter badge, thereby allowing a badge to be read in a multi-stage reading operation in a single dosimeter reader which is preferably automated. The optical laser converter includes a converter block assembly which defines multiple optical pathways therethrough. The convert block assembly is movable between different positions to align the different optical pathways with an incoming laser beam.

Abstract: Dosimeter reading methods and apparatus particularly useful in the measurement of heavy particle radiation dose exposure, such as from neutrons, protons, and alpha particles among others. The methods include exposing a dosimeter to a radiation environment to be measured. The dosimeter is thereafter stimulated, such as by a laser beam, to cause emission discharges from the dosimeter which are variable and indicative of the amount of ionizing radiation to which the element was exposed. Dosimeter elements which experienced an ionizing event from a heavy particle have higher levels of energy stored therein and produce higher luminescent or other emissions, thus characterizing that element or sample area as an eventful sample area. The number, portion or other measure of the eventful sample areas provides a basis for determining the level of radiation exposure due to the heavy particle or other discernable type of ionizing event.

Abstract: Disclosed are methods and apparatus for remotely measuring radiation levels. Such are particularly useful for measuring relatively high levels or dosages of radiation being administered in radiation therapy. They are also useful for more general radiation level measurements where remote sensing from the remaining portions of the apparatus is desirable. The apparatus uses a beam generator, such as a laser beam, to provide a stimulating beam. The stimulating beam is preferably of wavelengths shorter than 6 microns, or more advantageously less than 2 microns. The stimulating beam is used to stimulate a remote luminescent sensor mounted in a probe which emits stored luminescent energy resulting from exposure of the sensor to ionizing radiation. The stimulating beam is communicated to the remote luminescent sensor via transmissive fiber which also preferably serves to return the emission from the luminescent sensor.

Abstract: Serveral improvements in fiber optic sensing systems are disclosed. One improvement incorporates a dielectric filter applied directly to the sensing end of an optical fiber detector which has the characteristic that it reflects back a reference light beam of one wavelength while passing a sensing signal of a different wavelength which is modulated in some predetermined fashion beyond the filter. Both light signals are reflected back through the fiber and are, accordingly, attenuated in the identical or nearly identical fashion in response to various noise sources. The ratio of the intensity of the two signals is proportional to the sensed parameter and renders the system essentially self-compensating. The dielectric filter is preferably directly coated onto the exit end of the fiber through vapor deposition techniques.

Abstract: Apparatuses and methods for rapidly reading phosphors to determine the amount of energy stored therein. The stored energy is interpreted as a measure of the total exposure of the phosphor to ionizing radiation. The phosphor reading apparatus uses a laser to generate a laser beam. The laser beam power level is monitored by a laser power detector and controlled to maintain the power level at a desired value or values which can vary with time. A shutter or other laser beam interruption means is used to control exposure of the phosphor to the laser beam. The laser beam can be equalized using an optical equalizer so that the laser beam has an approximately uniform power density across the beam. The phosphor emits a visible or otherwise detectable emission which is measured as an indication of the radiation exposure of the phosphors. Also disclosed are preferred signal processing and control circuits including one system using a digital computer.

Abstract: A system and method for initializing and calibrating a fiber optic pressure transducer so that a measured intensity of light which varies as a function of pressure can be accurately translated to the value of pressure which produces that value of light intensity. The transducer includes an enclosed sensor tip having a diaphragm which is exposed to atmospheric pressure on the inside and the pressure to be determined on the outside as measurements are taken, the resulting pressure differential producing a related attenuation in light intensity. Calibration according to the present invention is performed by exposing the diaphragm to atmospheric pressure on the outside and sub-atmospheric pressure on the inside while transmitting light through the fiber in the usual manner. The sub-atmospheric pressure is changed gradually as simultaneous measurements are made of the intensity of light returned through the fiber and the actual value of the sub-atmospheric pressure at a number of discrete times.

Abstract: Non-contacting sensor apparatus having two tank circuits from which an indication of the position of the moving part of the sensor is developed by measuring the relative resonance frequencies of the two tank circuits. As the moving part of the sensor changes position and moves toward and away from the inductance coil of one of the tank circuits, the relative resonance frequencies of the two tank circuits change. The outputs of the two tank circuits are multiplexed and drive a pulse generator which develops a first series of pulses having a repetition rate which corresponds to the resonance fequency of one of the tank circuits and a second series of pulses having a repetition rate which corresponds to the resonance frequency of the other tank circuit. The relative times required to count the same number of pulses of each series of pulses provides an indication of the position of the moving part of the sensor.

Abstract: Non-contacting sensor apparatus having two tank circuits from which an indication of the position of the moving part of the sensor is developed by measuring the relative resonance frequencies of the two tank circuits. As the moving part of the sensor changes position, the relative resonance frequencies of the two tank circuits change. The outputs of the two tank circuits are multiplexed and drive a pulse generator which develops a first series of pulses having a repetition rate which corresponds to the resonance frequency of one of the tank circuits and a second series of pulses having a repetition rate which corresponds to the resonance frequency of the other tank circuit. The relative times required to count the same number of pulses of each series of pulses provides an indication of the position of the moving part of the sensor.

Abstract: A musical keyboard having keys which carry metal spoilers that alter the resonance characteristics of tank circuits associated with the keys as the keys move toward and away from the inductance coils of the tank circuits. The tank circuits are connected sequentially to a frequency sensing circuit which develops indications of key positions by sensing the resonance frequency of each tank circuit.

Abstract: A miniaturized pressure transducer, particularly suited for intravascular blood pressure measurement, utilizing a single optical fiber for transmitting light both to and from a flexible diaphragm having a light-reflecting surface on one side, the opposite side being exposed to and deflected in accordance with the pressure being measured. The end of the fiber through which light is transmitted to and reflected light received from the diaphragm is ground to form a spherical lens integral with the fiber, whereby light passing through the end of the fiber is focused at a predetermined focal point. The fiber is axially positioned so that the center of the diaphragm, which coincides with the lens axis, is at the focal point when the diaphragm is at maximum deflection, i.e., when its opposite surface is exposed to a predetermined, maximum anticipated pressure.