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: A transducer device for translating increments of linear displacement by means of opto-electronic sensing into increments of units expressed into units of volts. The device comprises an opto-electronic system, having a pair of co-planar, adjacently disposed radiation sensitive surfaces of square configuration, and a thereto facing, closely spaced surface of rectangular configuration being designed to emit a uniform pattern of radiation over its entire active surface. Wherein, the geometry of the emissive and sensing surfaces during relative movement provide a ratio of produced volt equivalent to the ratio of relative displacement between the emissive and sensing surfaces.

Abstract: The pressure of a gas within an enclosure is measured without making physical contact with the gas by focusing radiation from a laser onto a section of the gas and, while varying the intensity of the radiation, monitoring the section under measurement for electrical breakdown, as indicated by emitted light or suitable breakdown indicia, such as radio noise. The absolute gas pressure at the section of the gas under measurement is determined from a calibration curve relating the intensity of the beam to the pressure at which breakdown occurs for the particular gas being monitored.

Abstract: An optical switching element utilizes a spherical diaphragm mounted for snap-action movement between a concave and convex shape. A light beam is directed through a small aperture to impinge on the diaphragm. The aperture is positioned at a distance from the diaphragm equal to the radius of curvature of the diaphragm to obtain maximum reflection of the light when the diaphragm is in its concave shape. Upon movement of the diaphragm to the convex shape in response to an external stimuli, substantially all of the light is absorbed within the supporting housing with little or no light being reflected through the small aperture. The presence or absence of the light beam thus provides an indication of the external condition which may be a temperature value, pressure value or the like. The switch may also be utilized as a mechanical limit switch or a plurality of such optical switches may be fabricated to form a keyboard for entry of data into a computing system.

Abstract: A tire pressure sensing system has a sensor mounted on the tire hub, the sensor having a mask that is moved on change in tire pressure. Two rows of fibres at the end of a fibre-optic cable are positioned on opposite sides of a slit in the mask. The fibres of the two rows extend along a central core and an outer ring respectively of the cable. The rear end of the cable is mounted coaxially of the tire in alignment with a stationary cable having an inner core and an outer ring which extend to a radiation source and to a detector respectively. The source supplies radiation, via the cable, to the outer ring of the cable and hence to the row of fibres. Change in pressure moves the mask, thereby changing the amount of radiation received by the other row of fibres which passes to the outer ring of the stationary cable and thereby to the detector. The detector monitors the radiation and provides an output indicative of tire pressure.

Abstract: A signal processor is arranged to process polarized light signals obtained from a stress sensor of the type having a photoelastic element that responds to stress by causing a phase difference between components of the polarized light propagating through that element. The stress sensor provides two output beams, each of which has a different polarized component of the transmitted light. The signal processor employs a pair of photodetectors which respond to the intensities of the two polarized light beams by converting the polarized light into electrical signals. Those two electrical signals provide the inputs to a difference differentiator that provides an output proportional to the difference between the derivatives of the inputs. The two electrical output signals of the photodetectors are also applied as inputs to a multiplier whose output is related to the product of its inputs.

Abstract: Apparatus and method for sensing changes in pressure and for generating optical signals related to changes in pressure. Light from a fiber optic is directed to a movable surface which is coated with a light-responsive material, and which moves relative to the end of the fiber optic in response to changes in pressure. The same fiber optic collects a portion of the reflected or emitted light from the movable surface. Changes in pressure are determined by measuring changes in the amount of light collected.

Abstract: A Bourdon tube adapted for connection to a source of fluid pressure operates both a mechanically driven gauge pointer and an optical-electronic transmitter for providing operatively parallel output signals corresponding to values of pressure incurred by the fluid source. Simultaneously operative from the displaceable end of the Bourdon tube are both a mechanical movement for effecting amplified displacement of the pointer relative to a dial plate and an opaque vane displaceable within the transmitter between a photoemitter and a pair of photosensors. Circuitry in the transmitter responsive to discrete changes in light interruption between the vane and one of the photosensors emits a signal current corresponding to the pressure value at any given position of the vane.

Abstract: Signal output means (11) responsive to gas flow and particularly suited for use in gas flow indicator apparatus (10), has first and second pressure-datum valves (24, 25) arranged in downstream order in a gas conduit (16), the second pressure-datum valve (25) being arranged to open at a lower pressure difference than the first pressure-datum valve (24). A flueric amplifier (15) has a power jet port (28) connected to the gas conduit (16) on the upstream side of the first pressure-datum valve (24), opposed control pressure ports (26, 27) connected respectively to a chamber (22) formed between the first and second pressure-datum valves (24, 25) and to the gas conduit (16) downstream of the second pressure-datum valve (25), and a vent port (30) also connected to the gas conduit (16) downstream of the second pressure-datum valve (25). A pressure signal output by the flueric amplifier (15) in response to gas flow through the conduit (16) may be used to trigger a visual or audio warning device (14).

Abstract: A differential pressure sensor has a sensing diaphragm mounted in a body. The curvature of the diaphragm is representative of differential pressure across the diaphragm. Monochromatic light is direct from a source at the diaphragm to set up interference fringes which have varying spacings representative of the curvature, in the manner of Newton's rings. The fringes and their spacings are monitored and a computer calculates therefrom the curvature of the diaphragm and thence the pressure difference.

Abstract: An optical device for monitoring pressure is described. The device is capable of monitoring pressure in relatively hostile high temperature, high pressure environments through the use of a pressure-sensitive means having an all-glass housing. The subject optical device relies on the photoelastic effect produced when a material is subjected to a uniaxial stress to produce birefringent banding. In the subject device, polychromatic light is modified to produce a signal having wavelength-dependent intensity variations to allow the pressure-sensitive device to monitor pressure over a relatively wide range.

Abstract: An optical sensing system for detecting a physical parameter such as acceleration, temperature or pressure through parameter induced motion of an optical element in a fiber optic path. The motion of the optical element varies the light transmission through the path in which the optical element defines the relationship between motion and alteration in light transmission. In one embodiment the optical element includes a focusing system between an input and an output optical fiber to result in an increase in sensitivity by enhancement of the effect of motion of the optical element of the amount of light transmitted to the output fiber. The optical element may include or be attached to a mass to provide acceleration sensitivity for use in geophysical exploration. In addition, the optical element can be adapted to provide acceleration sensitivity in one direction in combination with insensitivity to acceleration in an orthogonal direction of particular use in such geophysical exploration.

Abstract: In a method of and apparatus for making remote measurements of temperature and pressure in a gas, laser beams are transmitted through the gas to a reflecting target, which may be either a solid surface or particulate matter in gas or the gas molecules and the return beams are measured to determine the amount of energy absorbed by the gas. For temperature measurements, the laser beam has a wavelength whereat the gas exhibits a relatively temperature sensitive and pressure insensitive absorption characteristic, whereas for pressure measurements, the laser beam has a wavelength whereat the gas has a relatively pressure sensitive and temperature insensitive absorption characteristic. To reduce the effects of scattering on the absorption measurements, a reference laser beam having a weak absorption characteristic is transmitted colinearly with the data beam having a strong absorption characteristic. The two signals are processed as a ratio to eliminate back scattering that is common to the two beams.

Abstract: An article and method is provided for remotely optically measuring high transient isotropic pressures. The arrangement employs a fluorescent crystal (such as a ruby) secured to one end of an elongate optical fiber waveguide for placement in the vicinity of a high pressure occurrence such as near an explosion. Light launched into the free end of the waveguide travels the length thereof to stimulate the crystal, which in the case of a ruby, fluoresces in the red, the wave length of which varies in response to isotropic pressure on the ruby. This red light output is transported back along the same optical fiber waveguide to the free end where its wavelength change is monitored and translated into a pressure value on the crystal.

Abstract: An intravascular catheter tip fiber optic pressure sensor wherein a lens element at the end of the fiber optic collimates the light emanating from the fiber and directs the light in a column towards a closely spaced reflecting diaphragm. The diaphragm is pressure responsive and modulates the focal length of the lens-diaphragm-mirror combination. Three optic fibers traverse the length of the hollow catheter tube, one carrying transmitted light to the tip, one carrying the reflected light from the diaphragm (i.e. the signal), and the third fiber carrying a reflected reference light. The reference detector provides a signal level to control the level of intensity of the light source.

Abstract: Vaginal muscle contraction is sensed by change of pressure within a flexible, hollow tubular member that is adapted to be compressed in response to muscle contraction. A simple pressure transducer embodies a pressure tube connected with the tubular sensing member and having an end covered by a flexible diaphragm that expands in response to increased pressure so as to progressively block light transmitted to a photosensitive resistor. The resistor controls an electrical signal that is employed to provide an audible or visual display that provides a measure of relative strength of muscular contraction and which also may be used in a biofeedback loop to inform the user of the intensity of the contraction. Accuracy of the inexpensive transducer is increased by compensating the output electrical signal for both nonlinearity and hysteresis of the distensible rubber diaphragm.

Abstract: A vortex flowmeter including a single optical fiber into one end of which a light signal can be transmitted from a source to the other fiber end where it is vortex modulated. Modulated light at the other end is then reflected to a receiver back along the same optical fiber. Relative movement between the other fiber end and a reflector serves to modulate the light signal. Embodiments are disclosed in which the other fiber end moves and the reflector is stationary. In the alternative case, the other fiber end is stationary and the reflector moves.

Abstract: A process control instrument, in which the resonant frequency of a vibrating string varies in accordance with changes in a process parameter being monitored, employs a pneumatic drive system to induce the string into oscillation. Pressurized gas is discharged through a port, such as a jet nozzle, which is disposed to allow the gas to impinge on the outer surface of the string. Variations in the alignment between the gas discharge port and the string permits different modes of vibration, one of which is particularly suitable for process measurement purposes. In a particular embodiment of the apparatus, an optical sensor detects the frequency of vibrations, resulting in an intrinsically safe instrument for use in explosive environments.

Abstract: Photoelastic sensing means, and more particularly photoelastic sensing means capable of providing high sensitivity for measuring pressure, force, displacement, acceleration or inertial force, proximity, temperature and other measurands. The photoelastic sensing means comprises a thin photoelastic member of transparent material having closely spaced top and bottom outer surfaces with peripheral edges and an edge surface extending between the peripheral edges of the other surfaces. Light flux is provided to the edge surface of the member at a first region for transmission by the member along a path to a second region at the edge surface where it is received and detected. The spacing between the top and bottom outer surfaces of the member is relatively small compared to the length of the path of the light flux in the member. The member is supported to produce bending stresses in the member in a direction transverse to the path of the light flux in the member with the application of force to the member.

Abstract: A monitoring apparatus for pressure sensitive devices is provided which detects the operating state of the monitored device, and which is designed to provide a reliable output even when operated in hostile, corrosive environments. The monitoring apparatus preferably includes a light source for transmitting a beam of light along a path of travel proximal to the monitored device, a light detector for detecting the light beam, and a member for adjusting the path of travel of the light beam in response to the actuation of the pressure sensitive device. Several alternative embodiments are disclosed.

Abstract: An ultralow pressure relief valve (10) is disclosed. Sealing fluid (24) is held in place by capillary forces inside capillary tube (12). When pressure in tube (11) exceeds capillary forces, sealing fluid (24) is forced into reservoir (14), protecting pressure gage (20) from overpressurization.

Abstract: A system for remote measurement of structural forces includes a plurality of microbend transducers mounted along the length of the structure for microbending an optical fiber in response to structural forces, such as stress acting upon an oil or gas pipeline or the like. An optical time domain reflectometer (OTDR) has a light source for launching a pulsed optical signal for passage through the fiber and a photodetector for sensing as a function of time the intensity of backscattered light reflected back through the fiber, wherein this sensed time function is correlated directly with discrete longitudinal positions along the length of the fiber and the structure. When one or more of the microbend transducers is activated to induce a microbend in the fiber in response to localized forces acting upon the structure, a portion of the backscattered light is lost at the microbend. This attenuation in backscattered light intensity is sensed quantitatively and positionally identified by the photodetector.

Abstract: A transducer utilizes a laser source, photoelastic waveguides, two optical beam paths and detectors for processing optical energy from the laser through a stress transfer medium and thereby detects stress forces present on the transducer. This allows forces such as pressure, strain, voltage, or current to be detected and converted from one form to another for measurement of the force and response thereto. Input forces are detected as optical frequency shifts and converted to electrical signal outputs for indicating circuitry. In an integrated optic format, the transducer package volume is small, allowing ready use in guidance or navigation systems. Light generated by the laser travels along two paths, is optically stressed by the force transfer member and is either combined or compared with a reference signal to obtain the stress intelligence.

Abstract: Tungsten halogen lamps require a fill pressure of several atmospheres. To verify the fill pressure at the time of manufacture the pressure is indirectly measured by first measuring the speed of sound within the lamp. A shock wave is produced within the lamp by rapidly heating a lamp filament or producing an arc between two adjacent filaments and measuring the time required for the shock wave to sequentially disturb two spaced light beams passing through the lamp. The speed of sound is determined from the measured time and the pressure is calculated from the speed of sound.

Abstract: A sensor for measuring stress, temperature, pressure, sound, etc. comprising an optical waveguide, preferably an optical fiber waveguide, a light source which injects light into one end of the waveguide, a deformer contacting and deforming the waveguide to cause light to couple from originally excited modes to other modes, and an optical detector to detect the change in light coupling caused by deformation of the waveguide.

Abstract: A differential pressure transducer of the diaphragm displacement type uses optical techniques to measure disphragm displacement. White light from a source is conducted by optical fibres to the transducer and interference is produced between light reflected at a thickened region of the diaphragm and a partially reflecting end face of the light conductor which is lapped flat and parallel to the diaphragm surface. The interfering reflected light is conducted back to a prism where it is dispersed onto photo-arrays. The wavelengths of dark fringes in the spectrum are measured to determine the displacement of the diaphragm. Measurements can be made on both sides of the diaphragm and used to eliminate dependence on reflective index.

Abstract: A servo instrument, particularly a servo altimeter, with a minimum of display error. The instrument comprises a capsule assembly, a sector adapted for rotation corresponding to the displacement of the capsule assembly, a photosensor for producing an output showing its angular position relative to the sector, a support for rotating the photosensor while supporting it adjustably in a direction of tracing the sector, a cam adapted to make the amount of the adjustment of the photosensor variable by the position of the support, a motor, means for generating a signal showing the rotating positional angle of the motor, and an amplifier for amplifying the output of the photosensor and driving the motor so as to maintain the output of the photosensor constant.

Abstract: The invention discloses a monitoring device for monitoring vacuum pressure of an electrical device employing an evacuated envelope. The invention provide, particularly, a pressure responsive monitoring device which comprises an electric field generating device of vacuum type, an electric field detector means including a light source for generating light, an electric field detector detecting change of the electric field of the electric field generator due to the change of vacuum pressure inside the envelope and controlling the light depending upon the change of the electric field, and photoelectric converter for converting the light controlled by the electric field detector to an electric signal which is employed to monitor the vacuum pressure of the envelope.

Abstract: The pressure-measuring device comprises a first chamber subjected to the pressure to be measured and a second chamber connected to the first through an opening fitted with a valve. The device further comprises a valve-control circuit and an element for detecting the instants at which the pressure difference between the two chambers attains a predetermined increment or decrement or a zero value. The detection element consists of a deformable pressure-tight wall placed between the two chambers and adapted to produce action on an optoelectronic, piezoelectric or electromechanical element which converts the deformation directly to logical signals. A bidirectional counter is provided for forward or backward counting of the increments and decrements obtained.

Abstract: The following specification discloses a fiberoptic pressure gauge suitable for use with a tank of compressed gas. In particular, the tank of compressed gas can be utilized by an industrial worker, a fireman, or a diver wherein breathing gas has been stored in a tank to allow for delivery thereof to a user. The pressure within the tank which is indicative of the supply of gas for delivery to a user's mask, is monitored by means of a bourdon tube type of movement that is connected to a shutter overlying a lighting source, such as a light emitting diode (LED). The lighting source is in optical relationship to a plurality of fiberoptic bundles that terminate at a distal end in a plurality of ends that are placed in calibrated relationship to a plurality of numbers indicative of the pressure within the tank.

Abstract: A system for sensing pressure features an electrically passive sensing head connected to electrically active components by a fiber optic cable. A preferred embodiment combines a polariscope bracketing a quarter wave plate and a photoelastic medium. The dependence of the intensities of two polarization components of light emerging from the photoelastic medium on the pressure applied to the medium permits the measurement of that pressure in a manner that has quadratic error dependence on optical misalignment.

Abstract: Apparatus controls the maximum pressure of the fluid which can flow through a pump. The apparatus includes a disposable unit with an inlet for receiving fluid from a source, an outlet for transferring the fluid to a patient and a chamber communicating between the inlet and the outlet. A diaphragm across the chamber is constrained in accordance with the pressure of the fluid in the chamber. The diaphragm transmits the constraint to a stiffener.The disposable unit is removably attached to the pump casing. A knob is externally disposed on the pump casing and is adjustable to control the maximum force of the fluid in the disposable unit. The knob controls the force exerted on biasing means in a first direction. A force is also exerted against the biasing means in a second direction opposite to the first direction. This force is dependent upon the force on the stiffener.The biasing means may include a spring.

Abstract: An apparatus is disclosed for optically sensing pressure using evanescent wave coupling between two fiber optics. A support base with a channel holds the two waveguides, one on top of the other, with the portion of the waveguide having the cladding material removed in the channel. An upper member having a diaphragm is attached to the support base. The diaphragm has a pedestal attached that is in slight contact with one of the waveguides. When pressure is exerted upon the diaphragm, the waveguides are forced closer together thus affecting the amount of evanescent coupling therebetween.

Abstract: Proximity sensor for determining the distance between a reflective surface and the sensor utilizes two output light guides positioned with the receiving end of one guide closer to the reflective surface than that of the other. When the surface is close to the guide ends a relatively greater intensity of light will be reflected to the second guide; when the surface is further away a relatively greater intensity of light will be reflected to the first guide. At a predetermined intermediate null position the reflected light intensities will be equal. The device has uses, inter alia, in accurately positioning objects without wear-producing contact, e.g. in numerically controlled machine tool operations; thickness sensing or thickness controlling using single or dual sensors; force sensing; liquid level indication; meter relay actuation; rotational limitation, and the like.

Abstract: A method and resulting apparatus for implementing a unique optical sensor that is adapted to be interfaced with a low cost, compact fiber-optic transmission system to provide an accurate indication of a sensed physical parameter (e.g. temperature) of a remote sample. The sensor is fabricated so as to include a semiconductor material that has optical-wavelength-dependent filter characteristics that may be varied as a function of a physical parameter such as temperature. In one embodiment, a graded optical filter fabricated by using thin-film deposition techniques on an amorphous semiconductor material, provides position responsive high-pass filter characteristics. Such filter characteristics are then utilized by moving a light source as a function of a physical parameter and generating an optical signal therefrom having a cutoff frequency dependent upon the position of the light source.

Abstract: A sensor for measuring stress, temperature, pressure, sound, etc. comprising an optical waveguide, preferably an optical fiber waveguide, a light source which injects light into one end of the waveguide, a deformer contacting and deforming the waveguide to cause light to couple from originally excited modes to other modes, and an optical detector to detect the change in light coupling caused by deformation of the waveguide.

Abstract: An optical device for measuring both slight positive and negative pressure differences by means of a light intensity change characterized by a gradient lens having a first and second end face being mounted in a housing part with a second end face spaced from a partially reflective membrane which is secured to the housing part to form a first chamber of a first volume and a second chamber of a second volume.

Abstract: An optical device for measuring slight pressure differences by means of a light intensity change characterized by a membrane extending across a recess of a housing part to form a first chamber of a first volume which is isolated from a second chamber on the opposite side of the membrane, a right angle isosceles glass prism mounted in the recess with a hypotenuse surface facing said membrane and extending parallel thereto, an input optical waveguide coupled to one short side surface of the prism extending to the light source of a given light intensity for coupling light from said source into the prism and an output optical waveguide being coupled to the other short side surface of the prism for output coupling light from the prism to a measuring device.

Abstract: An apparatus for pressure measurement employs fiber optics to transport a broadband beam light to and from a remote electrically passive sensing head. In the sensing head, a linearly polarized beam is phase shifted in a birefringent plate, then passed through a photoelastic pressure sensor and a polarization analyzer. The wavelength for which the output light has an intensity minimum is a measure of the applied pressure.

Abstract: An optical transducer for converting pressure variations to variations in amplitude of an optical signal. A first optical transmission line is positioned above a base in a manner to maintain its end face stationary while a second optical transmission line is positioned above the base in a manner to permit the axis to be displaced from the axis of the optical fiber with the stationary end face in accordance with variations of pressure applied thereto. Optical signals propagating in one of the optical transmission lines will couple to the other with a coupling factor dependent upon the axial displacement of the optical fibers. Under conditions of continuous pressure variations, such as that created by an incident acoustic wave, the coupled optical signal will be amplitude modulated in accordance with the pressure variations.

Abstract: A system is disclosed for detecting the position of the pointer of a gauge. The system includes a stationary light source which is positioned adjacent the pointer. A lens receives the light from the light source and redirects the light in at least one elongated light beam directed toward the pointer. In the preferred embodiment, the light source is located along the pointer's axis of rotation and the lens bends the light rays 90.degree. to form at least one arcuate light beam. A plurality of elongated light beams can be used and variations of different shapes of light beams can readily be used by so designing the lens means. A light sensitive detector is positionable in the gauge itself and is movable along a guided path on the opposite side of the pointer than is the light source. The guided path generally follows the particular shape of light beams that is directed toward the needle.

Abstract: A control device having a housing provided with an actuator chamber separated from a pressure differential chamber by a wall having an opening therethrough receiving an axially movable actuator pin that transmits axial movement of a movable part in the pressure differential chamber to the actuator chamber, the actuator pin being separate from and engageable with the movable part. An optical switch unit is disposed in the actuator chamber and the actuator pin has an interrupter vane for actuating the optical switch unit when the movable part axially moves the actuator pin to a certain axial position relative to the housing. The actuator pin has an orientation arrangement that cooperates with an orientation arrangement of the wall opening to maintain the interrupter vane of the actuator pin in proper rotational alignment with the optical switch unit.

Abstract: A mechanically actuated, piezoelectrically powered, fiber optic connected ght valve (shutter) utilized as a sensor to detect mechanical motion (pressure) or displacement. A piezoelectric element responds to pressure to generate an electrical signal which is applied to a Kerr cell containing nitrobenzene; the signal in turn renders the nitrobenzene transparent and light via fiber optic means is allowed to pass through the Kerr cell and return to the light source location for sensing.

Abstract: A temperature or pressure gauge capable of providing a magnified output indication of a respective sensed temperature or pressure of a fluid. Overlapping surfaces are movable relative to one another in response to sensed changes in temperature or pressure of a fluid. Each surface is provided with an aperture, a light controlling edge, or an indicator which overlaps and intersects at an acute angle a respective aperture, edge or indicator on the other surface. Rotary motion or other motion induced by the sensing element is translated into linear movement of the point of intersection of the two apertures, edges or indicators, the linear movement being greater in magnitude than the movement of the sensing element. This gauge is suitable for strip chart recording, for visual observation or for electrooptical reading.

Abstract: A pressure sensing device has a light source, and an optical sensor for externally sensing a predetermined change in the pressure within a sealed system which has a conventional gauge. Illumination from the light source is reflected off of the gauge dial and detected by the optical sensor. When the pressure in the sealed system changes a predetermined amount, the needle on the gauge moves so as to interrupt the illumination reaching the optical sensor. The optical sensor in turn produces a voltage that can be used to turn on a light or other indicator.

Abstract: In order to provide immunity against vibrations, a pressure sensor for detecting the prevailing manifold suction pressure in an internal combustion engine, for example, has a movable chamber which responds to the varying pressure and thereby changes the distance between a diffuse reflector and an optical detector assembly. The detector assembly includes a light source, a first light-sensitive detector and a second light-sensitive detector. The second detector is connected to a regulator which so controls the electrical power to the light source that the induced photo current in the second detector remains substantially constant independently of the distance between the reflector and the detectors. A number of embodiments is presented.

Abstract: A differential sensor unit precisely monitors ambient pressure within a confined space, such as blood pressure or intracranial pressure of a human patient, utilizing fiber optic light guides. Three light guides pass within a pneumatic line into one end of a rigid cylindrical envelope which may be inserted into a vein or artery or implanted in the skull. The other end of the envelope is bounded by a flexible membrane. Of the external ends of the guides, one faces a light source and each of the others faces a light detector. A reflective surface is attached to the internal face of the flexible membrane.

Abstract: A pressure transducer has a capsule having two chambers separated from one another by a diaphragm. The capsule is made entirely of a glass-ceramics material, such as, lithium alumino silicate. One of the chambers is sealed and has a lens with a curved surface adjacent the diaphragm such that, when the capsule is illuminated, a Newton's Rings pattern is produced by interference between light reflected from the surface of the lens and the diaphragm. Pressure is communicated to the other chamber so as to cause the diaphragm to be deflected into or out of the sealed chamber with a consequent shift in the interference pattern which is used to provide a measure of the pressure change. The capsule also has two further chambers which are identical to the first two chambers and which are both sealed. One of these further chambers is illuminated to produce a second interference pattern.

Abstract: An optical pressure transducer utilizing a deformable diaphragm having a reflective surface in which a fiber optic bundle having at least 100 optical fibers is randomly divided at one end into two bundles consisting of a light source bundle, the end of which is irradiated by a light source, and a reflected light bundle, the end of which conveys light reflected from a pressure-sensitive diaphragm to a light detection means.

Abstract: A partial pressure gauge utilizes an efficient electron collision excitation source yielding de-excitation radiation characteristic of residual gases. The intensity of a given spectral line is proportional to the partial pressure of the gas having such spectral line, and the current drawn from the excitation source provides a measure of the total pressure. A calibration technique based upon comparing the emitted light intensity with the ion currents associated with the excitation process yields an accurate measure of the relative partial pressure. Use of a filter to selectively pass radiation from a known constituent in known proportion in ambient gas provides an indication of the presence of a leak without the need for probing with a test gas. Provision for passing an evaporant stream through the excitation region permits accurate monitoring of the evaporant flux from which depostion rate is determined.