Particle-size spectrometers

Claim 2

A particle-size spectrometer in which a stream comprising a carrier fluid medium containing particles under test, is conducted through a slender beam of light, a photomultiplier being arranged to receive scattered light appearing on the particles, the concentration and/or size distribution of the particles being determined with reference to the output signals of the photomultiplier, said spectrometer comprising a chamber through which said stream containing the particles and said beam of light pass, said chamber comprising an Ulbricht sphere-type photometer for measuring stray light over substantially the full solid angle, a center of stray light being formed where said stream and said beam of light intersect, said chamber having an inner surface which surrounds the center of stray light at least along an arc which extends up to the edge of the beam of light both in front of and behind the center of stray light, said inner surface having a light exit aperture therein to receive and conduct the stray light to the photomultiplier which is connected to the chamber, the cross-sectional area of the aperture being small with respect to the surface area of the sphere, and a screen positioned in the chamber to shade the aperture from receiving direct light from the center of stray light.

Claim 3

A particle-size spectrometer according to claim 1, wherein the stream containing the particles and the light beam intersect in the centre of the chamber substantially at right angles.

Claim 4

A particle-size spectrometer accordIng to claim 1 wherein a light entry aperture is provided in the wall of the chamber, a tube within the chamber to surround the path of the beam of light, said tube extending from the light entry aperture to the center of stray light, and having a light absorbent interior surface and a reflective exterior surface.

Claim 5

A particle-size spectrometer according to claim 1, wherein a first translucent capillary tube is connected to a source of the stream and is arranged to conduct the stream to the center of the chamber, a second translucent capillary tube being arranged coaxially with and surrounding the first capillary tube at a distance therefrom, this second translucent capillary tube extending further toward the center of stray light than said first capillary tube and tapering continuously toward the latter, the annular space between the two capillary tubes serving to conduct particle free carrier fluid of the stream.

Claim 6

A particle-size spectrometer according to claim 1, wherein the ends of the first and second capillary tubes directed towards the centre of the chamber have an elongate cross-section for relatively high stream throughputs, the longitudinal direction of which cross-section extends parallel to the direction of the light beam.

Claim 7

A particle-size spectrometer according to claim 1, wherein the interior of the chamber is filled with the same fluid though particle-free, as the stream containing the particles.

Claim 8

A particle size spectrometer having a chamber, there being a light entry aperture in the wall of the chamber, light conductors leading from a photomultiplier and extending into the chamber, said light conductors being arranged to receive scattered light over a plane angle of substantially 180* essentially in a common plane with the light beam, the ends of the light conductors within the chamber being directed toward the center of scattered light, an arcuate surface formed by said ends of the light conductors surrounding the center of scattered light for nearly 180* wherein a first adjustable reflector is arranged to extend from the end of the arcuate surface near the light entry aperture and defines a screen forming one of the edges of the beam such that a portion of the light is diffracted at the edge of the reflector, a second adjustable reflector extending from the other end of the arcuate surface into the immediate vicinity of the light beam, both reflectors being so arranged as to reflect light from the scattering center toward said arcuate surface, a screen within the chamber, said screen being arranged radially of said scattering center, the side of the screen facing said first reflector having a light absorbent surface for the purpose of absorbing said light diffracted at the edge of said first reflector.

Claim 9

A particle size spectrometer having a chamber, there being a light entry aperture in the wall of the chamber, light conductors leading from a photomultiplier and extending into the chamber, said light conductors being arranged to receive scattered light over a plane angle of substantially 180* essentially in a common plane with the light beam, the ends of the light conductors within the chamber being directed toward the center of scattered light, an arcuate surface formed by said ends of the light conductors surrounding the center of scattered light for nearly 180* wherein a first adjustable reflector is arranged to extend from the end of the arcuate surface near the light entry aperture and defines a screen forming one of the edges of the beam such that a portion of the light is diffracted at the edge of the reflector, a second adjustable reflector extending from the other end of the arcuate surface into the immediate vicinity of the light beam, both reflectors being so arranged as to reflect light from the scattering center toward said arcuate surface, a screen within the chamber, said screen being arranged radially of said scattering center, the side of the screen facing said first reflector having a light absorbent surface for the purpose of absorbing said light diffracted at the edge of said first reflector.

Claim 10

A particle-size spectrometer according to claim 7, wherein a first translucent capillary tube is connected to a source of the stream and is arranged to conduct the stream to the center of the chamber, a second translucent capillary tube being arranged coaxially with and surrounding the first capillary tube at a distance therefrom, this second translucent capillary tube extending further toward the center of stray light than said first capillary tube and tapering continuously toward the latter, the annular space between the two capillary tubes serving to conduct particle free carrier fluid of the stream.

Claim 11

A particle-size spectrometer according to claim 7, wherein the ends of the first and second capillary tubes directed toward the center of the chamber have an elongate cross-section for relatively high stream throughputs, the longitudinal direction of which cross-section extends parallel to the direction of the light beam.

Claim 12

A particle-size spectrometer according to claim 7, wherein the interior of the chamber is filled with the same fluid though particle-free, as the stream containing the particles.

Claim 13

A particle-size spectrometer according to claim 7, wherein the arcuate surface is narrow relativE to the internal dimension of the chamber.

Claim 14

A particle-size spectrometer according to claim 7, wherein the inner wall of said chamber has a light-absorbent surface.