Abstract: The liquid nephelometer has an elongate, tubular housing for containing a liquid sample to be measured for the concentration of foreign materials, a light source located adjacent one or both ends of the housing for directing a beam of light along an axial path through the housing, a light restrictor having a aperture of reduced cross sectional area to divide the interior of the housing into a first or sensing chamber having a known volume and a second chamber and to limit the passage of the scattered light between the two chambers, and light detecting means for detecting light scattered by foreign material in the liquid present in one or both of the chambers and producing a signal representative of the concentration of such foreign material.

Abstract: A reflection densitometer includes a light source and a photodetector having an output which has a signal component characteristic of the amount of reflected light received from a surface to be measured and a noise component. The noise component of the output is isolated in time by switching the light source on and off so as to create alternating first and second time periods during which the output of the photodetector is characteristic of only the noise component and in which the output of the photodetector is characteristic of both the signal component plus the noise component, respectively. The output of the photodetector during the second time period is subtracted from the output during the first time period to obtain a signal characteristic of only the output of the photodetector characteristic of relected light received.

Abstract: A dither motor for dithering a plurality of inertial sensors includes an outer support ring, a plurality of reeds and a plurality of mounting supports. The outer support ring may be generally circular or polygonal in shape. Each reed of the plurality of reeds has a hub end and an outer end wherein the hub ends are connected to a common hub and the ring ends are connected to the outer support ring. The plurality of reeds are arranged to be disposed at equal angles from each other and extend radially outwardly from the hub. The plurality of mounting supports extend outwardly from the hub and each mounting support is located between two of the plurality of reeds. The mounting supports are also equally spaced apart. Further, each reed has a means for oscillating connected thereto such as piezoelectric elements.

Abstract: An apparatus for predicting milk coagulum cut-time in a cheese making process includes a light source, a sensor or detector for sensing diffuse reflectance of light from said milk and a controller for analyzing the diffuse reflectance and accurately predicting the cut-time to significantly enhance overall yield. More specifically, the apparatus includes an optical probe which may be suspended over the milk or attached to a wall of a fermentation vessel in which the milk is contained. A method for predicting milk coagulum cut-time includes the steps of (a) directing light from a light source toward milk undergoing enzymatic hydrolysis; (b) sensing diffuse reflectance of that light from the milk; (c) analyzing the sensed diffuse reflectance profile and (d) signaling the cut-time. The sensing occurs at between 400 to 6000 nm. Specific mathematical formulae for the analyzing steps are also disclosed.

Abstract: A displacement detector device has a source of laser beam; a diffraction grating for separating the laser beam into a plurality of beam components; a filter for shielding the beam components other than the two beam components of .+-. primary order produced by the diffraction grating; a wavelength plate operable to vary the polarized state of one of the two beam components of .+-. primary order; a lens element for focusing the two beam components of .+-. primary order on a displacement plane and a reference plane, respectively; and a photosensor. The two beam components of .+-. primary order focused on the reference and displacement planes, respectively, are subsequently reflected therefrom and are then collimated by the lens element after having again entered the lens element in substantially overlapped relationship.

Abstract: An instrument for monitoring the color change of an indicator element sealed within a sterile vessel and exhibiting a color change in response to a change in the pH of CO.sub.2 level within the sterile vessel as a result of microbacterial growth within a specimen contained in the sterile vessel. The present invention includes means for continuously monitoring the absolute value of the pH and or CO.sub.2 level within the vessel and or monitoring the rate of change of the absolute value of the pH level.

Abstract: An electrophotographic apparatus having a densitometer, which measures material density located on a substrate by detecting and analyzing only a single diffuse electromagnetic energy signal reflected off of the density of material located on the substrate. Specifically, the apparatus must first be compensated for environmental and individual machine differences using a high density of the material. Moreover, once compensated, the apparatus is calibrated to determine the relationship between diffuse signals and material density. This relationship is calculated by sampling a clean substrate and low densities of the material. Once the relationship is determined, densities of material can be calculated given a corresponding diffuse signal. The calibrated and compensated density calculations enable accurate monitoring and adjustment of the electrophotographic apparatus color toner development systems.

Abstract: Optical metrology method and apparatus wherein three optical wavelengths of a fixed polarization are generated and separated into a reference beam (RB) and a measurement or object beam (OB) having, ideally, equal optical path lengths. After reflecting from surfaces being measured OB is combined with RB and provided to sensors which measure the intensity associated with each of the wavelengths. Any difference between the intensities is indicative of a difference in the optical path lengths of OB and RB and is a function of the polarization state of each of the three returned wavelengths. Differences in optical path length may be indicative of a difference between a reference surface and a test surface, or a difference in thickness or index of refraction across an object. Two multi-mode laser diodes (12, 14) are provided for generating the three optical wavelengths.

Abstract: The present invention is directed to a sensor which utilizes an optical fiber interferometer to detect the absorption of a modulated laser beam by a particular chemical species. In particular, one embodiment of the present invention comprises a fiber optic system in which light from a continuously operating laser is modulated prior to passing through a region containing a chemical species of interest. Absorption of the light from the laser causes heating of the chemical species which, in turn, emits thermal energy that is transferred to an optical fiber that is situated in close proximity to the region in which the light is absorbed. In turn, the increase of the temperature of the optical fiber results in a change in the fiber's refractive index, thereby resulting in a change in the transmittance of said interferometer. The change in transmittance of the fiber is converted into an electrical signal in a photodetector.

Abstract: A mismatched path length fiber optic interferometer is optically coupled to an optical fiber and configured to form an omnidirectional acoustic sensor. A second mismatched path length fiber optic interferometer is optically coupled to the optical fiber and configured as a first gradient sensor. A second fiber optic gradient sensor is also optically coupled to the optical fiber. A detector optically coupled to the omnidirectional acoustic sensor and to the gradient sensors converts optical signals output therefrom to electrical signals indicative of the magnitude and direction of changes in an acoustic field. The omnidirectional acoustic sensor may include a length of optical fiber wrapped around the housing while the gradient sensors are mounted inside the housing. The housing perferably has a volume that is adjustable for controlling the buoyancy thereof. Each gradient sensor preferably comprises a pair of mandrels formed to enclose chambers. Optical fiber coils are formed on the mandrels.

Abstract: A flow cytometer has a flow cell containing a flowing stream of a number of particles which flow one at a time in a straight line based on hydrodynamic methods, a radiator for radiating a light on the particles flowing through the flow cell, a forward scattered light detector for detecting light scattered in the same direction as the radiating light, and a right angle signal light detector for detecting light radiated in a right angle with respect to the direction of the radiating light. The flow cell and the forward scattered light detector are contained in a single mount, and the mount is supported on a bench through an adjusting mechanism. In this way, the flow cell and the forward scattered light detector can be adjusted without disturbing their locations relative to each other.

Abstract: A method and an apparatus for measuring a displacement between two objects. Corresponding pairs of regions of the two objects each have at least one diffraction grating which generate two-dimensionally distributed diffracted light beams. These light beams are diffracted and caused to interfere with each other in the paired regions, whereby two-dimensionally distributed diffracted interference light beams are emitted. A light beam of a specific order is detected from each of these diffracted interference light beams, and is converted into a beat signal. The displacement is obtained in accordance with the phase difference between these beat signals.

Abstract: A ring laser gyro has an optical resonator (12), forming a loop- or ring-shaped beam cavity, a lasing medium (14) arranged in the resonator for furnishing, when stimulated, two laser oscillation pulses circulating in the resonator in opposing directions, and a device for measuring the change in frequency and/or wavelength of the laser oscillation pulses as a function of the rotation of the resonator. A saturable absorber (16) is arranged in the laser resonator for the purpose of fixing the standing wave resulting due to the laser oscillation pulses circulating in the opposing directions as regards the laser resonator. Rotation of the laser resonator changes the wavelengths of the laser oscillation pulses circulating in opposing directions. The change in wavelength and/or the difference in the frequencies of the laser oscillation pulses constitute a measure of the rotation rate. No effect making it difficult to measure low rotary speeds in known ring laser gyros occurs in the present ring laser gyro.

Abstract: The damping of the fiber coil of a fiber gyroscope is automatically corrected or newly determined in a microprocessor by repeating a calculation program in which a previously known damping factor of the fiber coil is replaced by a more recently determined damping factor. The calculation program is repeated until the calculated damping factor converges toward a fixed value. In this way, changes in the damping factor, e.g. due to aging of the fiber coil, due to splicings in the fiber coil, are ascertained and automatically corrected.

Abstract: A projected fringe interferometer for measuring the topography of an object periodically steps the phase angle between a pair of light beams emanating from a common source. The steps are .pi./2 radians (90.degree.) apart and at each step a video image of the fringes is recorded and stored. Photodetectors measure either the phase angle .theta. of the beams or 2.theta. either of which is used to control one of the light beams so the 90.degree. .theta. is accurately maintained. A camera, a computer, a phase controller and a phase modulator established closed-loop control of .theta.. Measuring the phase map of a flat surface establishes a calibration reference.

Abstract: The invention relates to a fibre optic measuring device of the type in which the change in a measured parameter generates a phase difference between two waves in a SAGNAC ring interferometer (2). Electronic means (7) comprise a processing system (9) delivering a signal depending on the measured parameter and electronic means (12) controlling the phase modulator (4). The electronic means (12) produce a control signal for the modulator determined in such a way that the phase difference .delta..PHI..sub.m which it produces between the counter-propagating waves periodically takes the following four successive values: ##EQU1## where .PHI..sub.o is a constant phase shift and it depends on a, and a is a positive constant satisfying the condition: cos .PHI..sub.o =cos a.PHI..sub.o.

Abstract: In a ring resonator gyro the CW and CCW beams are modulated to provide each with a spectrum including a carrier and an upper and a lower side band. The upper side band of one beam is kept at a resonance by a path length control loop 24 and the upper side band of the other beam is kept at a resonance by a rate control loop 40.

Abstract: In a laser interferometer type length measuring apparatus, a measurement laser beam will be influenced by disturbance such as air fluctuation and a change in air pressure distribution due to movement of an object so that a displacement of the object cannot be accurately measured. In order to obviate such an inconvenience, air controlled at a predetermined temperature is uniformly blown at a fixed speed on the entire optical path of the measurement laser beam.

Abstract: The visual monitoring apparatus includes a transparent tube section with coupling flanges at each end for coupling to adjacent conduit sections carrying a stream of conditioned sludge which includes agglomerated solid bodies. Control rods extend between the coupling flanges to strengthen the tube. A strobe light is mounted in a housing which is mountable alongside the tube and closely conforms to the shape thereof for confining the strobe light to a predetermined area of the tube and isolating that area from ambient light. The housing accommodates the control rods therethrough and contains a mirror which directs light reflected from the illuminated contents of the tube along a viewing path through a view port in the housing which is closed by a door or hatch. The frequency of the strobe can be adjusted to correspond to the flow rate of the fluid in the tube for creating the visual impression of substantially stopping the movement of the solid bodies in the tube.

Abstract: A media discriminating and presence sensor that can detect and discriminate between paper and transparency uses a light emitting diode and two defectors configured so as to measure both diffuse and specular reflectivity of the media, and a media support surface that suppresses unwanted reflections.