Abstract: Method and apparatus for analyzing particles based on different depolarizing structure associated with the different particle types. Cells in a flow cytometer are illuminated with a linearly polarized light, producing scattered depolarized light whose intensity range, at a selected measuring angle, and in a suitable discriminating space, is used to analyze different particle types.

Abstract: There is disclosed a system in which, according to the time domain method, a laser light is irradiated to an object to be measured, photon pulses based on the scattering light from the object to be measured are received, time series data are generated based on the light receiving signal, and based on the time series data thus generated, the particle size distribution of particles in the object to be measured is measured. Thus, the present invention achieves a considerable reduction in time required for finally obtaining the particle size based on the measured data, as compared with a conventional system using a calculator program.

Abstract: A method and apparatus for separating particles by means of a contra-flow centrifuge, wherein a monitor system is used to analyze or control the separation process. The monitor system used impinges a monochromatic light beam on a sample of the separated particles, and measures the light scattering not only in the beam-forward direction, but also in the beam-reverse and beam-lateral directions. This reduces the processing time and increases the reliabiity of output data.

Abstract: The invention relates to the measurement of the granulometry of a cloud of particles or of the roughness of a surface in real time and without contact, by means of an apparatus comprising: a convergent lens (9) adapted for forming a diffraction pattern of the cloud of particles or of the surface: multiplier means (10) adatped for multiplying this diffraction pattern, in intensity, by a function f(r) such thatA(r.sup.1.5 +Br.sub.o.sup.4)<f(r)<A (r.sup.4 +Br.sub.o.sup.4)withA=constant determined by calibration of the apparatusB=constant: o<B<0.1r=distance measured in the focal plane of the lens with respect to the optical axis thereof,r.sub.o =maximum useful radius of the spatial filter,and means (11, 24) adapted for carrying out a reverse Fourier transform on the result of the above intensity multiplication, whose result forms the desired spectrum of the granulometry of the cloud of particles or the desired spectrum of the roughness of the surface.

Abstract: A flow field seeded with small particles is illuminated by collimated, monochromatic laser light sheet 16. Doppler shifted scattering from particle motion is imaged by an optical system 22. An optical frequency-to-intensity converter 24 is located at the image plane such that the transmitted image contains a simultaneous two-dimensional measurement of flow velocity along a direction determined by a laser beam and observer (converter) direction. These images can be observed directly or through a TV-2-D array camera and monitor or processed through a computer system 28.

Abstract: An apparatus and method are disclosed for detecting the presence of particles on the surface of an object such as the front side of a patterned semiconductor wafer. A collimated beam of light is directed onto an area on the surface of the object at a grazing angle of incidence. A detector positioned above the surface detects light scattered from any particles which may be present on the surface, but not specularly reflected light. The output of the detector is fed into a computer where the information is processed and then displayed on a display. The surface is prepositioned relative to the incident light beam so that the diffracted light from the surface and the pattern on the surface is at a minimum. The object is then moved translationally to expose another area to the incident light beam so that the entire surface of the object or selected portions thereof can be examined, an area at a time.

Abstract: A fiber optic doppler anemometer comprises a source of coherent light, a directional coupler formed by the combination of a pair of single-mode optical fibers, and a photoelectric transducer. The first end of the first fiber receives an incident beam of light from the source and guides it through the directional coupler to the second end of the first fiber, which is located adjacent to a body of moving particles to be measured, where both the second end of the first fiber and the moving particles reflect a portion of the incident light back into the first fiber. The reflected light, which has a frequency different from that of the incident beam entering the first fiber, is directed back through the directional coupler which couples a portion of the reflected light toward the first end of the second fiber. The photoelectric transducer receives the light emerging at the first end of the second fiber and converts it into analogous electrical signals.

Abstract: An apparatus for measuring dew-point of a gas stream includes a sensor cell having a probe, means for cooling the probe, means for transmitting light to the probe surface in a pressurized chamber, means for receiving returned light scattered from the cooled probe surface, and means for determining dew-point from a reduction in scattered light intensity. The probe surface is provided in its center with a depression of low angle.

Abstract: A condensation nucleus counter (1) for measuring particulate concentration within a gaseous environment, including an inlet orifice (3) leading to a flow path (5) within saturator (4). The resultant vapor (10) enters a condenser section (11) wherein the particulate matter suspended within serves as the nucleus for condensation. The enlarged droplets (23) thus formed enter a conventional optical particle counter section (15).

Abstract: An apparatus and method are disclosed for detecting the presence of particles on the surface of an object such as the front side of a patterned semiconductor wafer. A vertically expanded, horizontally scanning, beam of light is directed onto an area on the surface of the object at a grazing angle of incidence. A video camera positioned above the surface detects light scattered from any particles which may be present on the surface, but not specularly reflected light. The surface is angularly prepositioned (rotated) relative to the incident light beam so that the diffracted light from the surface and the pattern of lines on the surface is at a minimum. The object is then moved translationally to expose another area to the incident light beam so that the entire surface of the object or selected portions thereof can be examined, an area at a time.

Abstract: In a fiber-optical Doppler anemometer for measurement of fluctuating light or the Doppler broadening of laser light scattered by a scattering medium, for example by particles in motion, coherent laser light is passed via a fiber-optical coupler (1) and a submerged fiber-optical probe (2) into the scattering medium, and the light scattered back by the scattering medium is picked up by the submerged fiber-optical probe (2), branched by the fiber-optical coupler (1) and passed to a photodetector (3).

Abstract: A scattered light type smoke detector wherein a light source and a photo-cell are so disposed that light from the light source does not directly enter the photo-cell and the photo-cell is adapted to receive light from the light source scattered by intervening smoke to detect the presence of smoke. The photo-cell is accommodated in a cylindrical recess formed in a smoke detecting holder. The inner face of the cylindrical recess and the surface of the smoke detecting holder extending along the optical axis of the photo-cell has light traps formed in sawteeth configuration in section for reflecting light other than the scattered light to be detected into a direction not towards the photo-cell.

Abstract: A highly sensitive and rapid method for quantitatively assaying analytes in liquid media by directly measuring changes in particle size distribution of reagent particles having analyte insolubilized thereon in a system undergoing antibody-induced aggregation has been developed. The amount of analyte initially present can be determined by measuring the change in the distribution of particle size with time, the concentration of a particular size particle at a given time, the rate of formation of a particular size particle, or the steady-state maximum concentration for a particular size particle.

Abstract: The disclosure teaches a device for measuring the dynamic properties of microparticles including at least two flat measuring bodies or discs spaced from each other, with the distance therebetween being adjustable and the space therebetween being filled with a suspension of microparticles to be measured. At least one of said bodies or discs is movable so that a defined magnitude of fluid shear stress is generated in the suspension. The device also includes means for passing a light beam through both bodies and said suspension so that, during rotation and when rotation is stopped, different diffraction patterns are generated. Means for measuring the diffraction patterns is also included thereby obtaining useful data concerning the dynamic properties of the microparticles.

Abstract: A method and apparatus for observing imperfections on the surface of and imbedded in an optical sample using a dark field technique. Linearally polarized laser light is entered by a prism-fluid index matching method which causes internal reflection at the critical angle. The internally reflected beam then coherently combines with the incident beam in the vicinity of the sample surface. This results in a standing wave pattern which can be adjusted by changing the laser wavelength, the angle of incidence or polarization to selectively illuminate variously regions at and below the surface. One polarization will have maximum intensity at the surface level while the alternate polarization will have a null at the surface level. Defects within the optical sample scatter light such that it does not reach the surface at an angle equal to or greater than the critical angle. This light is emitted from the sample surface and appears as a pattern of bright spots on a dark background.

Abstract: In electrophoretic apparatus measuring the velocity of particles in a fluid, a reference beam and a scattered beam scattered by the particles in the fluid at various scattering angles must be heterodyned in order that the Doppler frequency shift resulting from the scattering by the moving particles can be determined. The previous need for adjusting the optical path of the reference beam so that is always impinges with the scattered beam, independent of the scattering angle, upon the mixer or heterodyner is avoided by an automatic control of the direction of the reference and scattered beams relative to the mixer so that they both always impinge upon a predetermined location in the mixer independent of the scattering angle. The construction of the measuring cell and ways of mounting same in a housing to allow easy refilling and replacement are also disclosed.