Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
  • G01N15/02—Investigating particle size or size distribution
  • G01N15/0205—Investigating particle size or size distribution by optical means
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
  • G01N15/02—Investigating particle size or size distribution
  • G01N15/0205—Investigating particle size or size distribution by optical means
  • G01N15/0211—Investigating a scatter or diffraction pattern
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
  • G01N2015/03—Electro-optical investigation of a plurality of particles, the analyser being characterised by the optical arrangement

Definitions

• the present invention relates to a device for optical detection of particles ⁇ rule based on scattered light.
• the particles to be measured are irradiated with light and the scattered light on the particles collected by detectors such as Photodi ⁇ oden at certain angles, the signal is measured and inferred on the particle size.
• Inten ⁇ intensity of the scattered light however, especially in the range of particle sizes d ⁇ 200 nm, which are very serious health, with d A 6 small (Rayleigh scattering), ie very small particles only create a very small signal, and are thus difficult to measure. If one uses even two or more angles in the light scattering, in order to determine a particle size distribution (on the hand of eg the intensity ratios in the Mie theory), the scattering intensities at larger angles can become even smaller and a signal even more difficult to measure.
• GB 2474235 discloses a structure in which laser light is radiated into a passage intended for the particles to be measured and two identical mirrors designed as spherical caps are provided on both sides of the laser beam. Scattered light is directed by the mirrors into two detectors. In both known structures, the respective mirror arrangements lead to a considerable size. It is an object of the present invention to provide an arrangement for the detection of particles, which reduces the above-mentioned disadvantages. This object is achieved by an arrangement having the features of claim 1.
• the subclaims relate to advantageous embodiments of the invention.
• the inventive arrangement for detecting particles comprises a light source for irradiating the particles with egg ⁇ nem light beam.
• a light source for irradiating the particles with egg ⁇ nem light beam.
• This can be for example a laser diode or a light emitting diode (LED).
• the arrangement comprises at least two detection devices for receiving particles of the light scattered on the particles.
• photodiodes can be used as detection devices.
• the detection devices can also be realized as a single component in which a spatially resolved measurement can take place.
• the arrangement comprises at least two mirrors for focusing the light scattered by the particles in an angular range onto one of the detection devices.
• the mirrors are each an opening and are arranged interleaved so that undeflected parts of the light of the light source passes through the openings of the mirror.
• At least the largest of the mirrors is preferably designed in the form of a spherical zone, in particular in the form of a spherical cap.
• spherical zone while the outer surface of a Ku ⁇ gel slice is meant, which is cut out of a ball by means of two paral ⁇ Lelex levels.
• Ball cap refers to the lateral surface of a spherical surface from which more than half of the ball is cut away by means of a plane. In particular, all mirrors have this shape.
• the spherical zones or spherical caps can advantageously be arranged in a space-saving concentric manner, wherein the light can be directed to the respective detection device by tilting or laterally displacing a respective mirror. It is therefore at a small size still significantly increased light output compared to a solution without mirror he ⁇ ranges.
• FIG. 1 shows an arrangement 10 for detecting particles 13.
• the particles 13 are simply present in the region of the arrangement 10 or are supplied and passed through.
• the arrangement 10 has a laser diode 11. This is aligned so that it generates egg ⁇ nen laser beam 12 in the direction of the particles. Parts of the laser beam 12, which run unaffected by the particles, meet a light trap 14.
• the light trap 14 may for example consist of a deflection mirror and a suitably unreflective hollow body. It ensures that virtually no reflected laser light reaches the particles 13.
• reflectors are arranged around a point 15 on the laser beam 12.
• the point 15 lies in the direction of the laser beam 12 expedient behind the area in which the laser beam strikes the particles 13.
• these are a first mirror 16 and a second mirror 17.
• Both mirrors have the shape of a spherical zone.
• a sphere zone is a portion of a spherical surface which remains when a disk is cut from the sphere, the sphere zone being the remainder of the sphere surface in that disk.
• the Spie ⁇ gel 16, 17 are arranged interleaved. That is, the second, smaller mirror 17 is disposed entirely or substantially within the volume occupied by the first, larger mirror 16.
• the volume of the first mirror 16 means the volume of the spherical disk whose surface corresponds to the first mirror 16.
• 17 not take the two Spie ⁇ gel 16 in total, or barely more volume than the first mirror 16 alone.
• the mirrors 16, 17 are arranged nearly so that their axes, that is the line connecting the centers of the circles that represent their edges coincide with the course of the laser beam over ⁇ . However, they have a slight lateral displacement relative to the exact agreement, ie the mirrors 16, 17 are not arranged exactly concentric.
• the reflectors ⁇ struck from the first mirror 16 light is directed to a first photodiode 18 and the light reflected from the second mirror 17 light is directed to a two ⁇ th photodiode 19 is achieved. Because of the geometry of the Anord ⁇ voltage is the light which reaches the first photodiode 18, such laser light that is scattered by the particles 13 in a predetermined first angular range. The light which reaches the second photodiode 19, is laser light ⁇ that is scattered by the particles 13 in a certain second angle range.

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• Chemical & Material Sciences (AREA)
• Dispersion Chemistry (AREA)
• Physics & Mathematics (AREA)
• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Analytical Chemistry (AREA)
• Biochemistry (AREA)
• General Health & Medical Sciences (AREA)
• General Physics & Mathematics (AREA)
• Immunology (AREA)
• Pathology (AREA)
• Investigating Or Analysing Materials By Optical Means (AREA)

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Citations (7)

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• 2012
  • 2012-02-01 DE DE201210201423 patent/DE102012201423B4/de not_active Expired - Fee Related
• 2013
  • 2013-01-29 WO PCT/EP2013/051634 patent/WO2013113679A1/fr not_active Ceased

Patent Citations (7)

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