1. An apparatus for determining particle characteristics comprising:
a) illuminating means for illuminating one or more particles,
b) detecting means for detecting light scattered from one or more detected particles, wherein scattered light is received by said detecting means from each detected particle,
c) a reflector for directing light from the illuminating means, by means of or through a beam splitting means, to the detecting means,
wherein light from the reflector is combined with light scattered from one or more detected particles to produce an optical interference signal, and wherein said reflector is positioned generally between said beam splitting means and said particles, and wherein said reflector does not contact said particles, and
d) means for containing said particles.
2. The apparatus of claim 1, wherein the reflector is a partial reflector which partially reflects light from said illuminating means.
3. The apparatus of claim 2, wherein said partial reflector partially reflects light in a converging portion of light from said illuminating means and said partial reflector has generally a spherical shape with a center of curvature which is generally at a focal point projected from light rays, of said converging portion, which are incident upon said reflector.
4. The apparatus of claim 1, wherein said reflector is a partial reflector, which is generally flat and positioned generally at the focus of a converging portion of light from said illuminating means.
5. The apparatus of claim 1, wherein light from said illuminating means passes through a long volume of fluid to determine characteristics of one or more particles in said fluid, and wherein a flow direction of said fluid is generally parallel to a direction of light from said illuminating means.
6. The apparatus of claim 1, further comprising:
a) means for detecting a light source signal which is generally proportional to an optical flux of said illuminating means, wherein the effects of intensity fluctuations of the illuminating means are removed from said optical interference signal by calculating a difference between signals derived from amplitude variations of said light source signal and of said optical interference signal, and
b) means for calculating a difference between said signals.
7. The apparatus of claim 1, including means for correcting a power spectrum of a signal from said detecting means, to remove a portion, of said power spectrum, which is not caused by light scattered from particles of interest, comprising:
a) means for measuring a first scatter detector signal, as a function of time, with particles in a volume of dispersant which volume is viewed by said detecting means,
b) means for calculating a first power spectrum of said first scatter detector signal,
c) means for measuring a second scatter detector signal, as a function of time, with generally no particles in a volume of dispersant which volume is viewed by said detecting means,
d) means for calculating a second power spectrum of said second scatter detector signal,
e) means for measuring a third signal, as a function of time, from a detector which monitors intensity of said illuminating means, the third signal being derived while said first scatter detector signal is measured,
f) means for calculating a third power spectrum from said third signal,
g) means for measuring a fourth signal, as a function of time, from a detector which monitors intensity of said illuminating means, the fourth signal being derived while said second scatter detector signal is measured,
h) means for calculating a fourth power spectrum from said fourth signal,
i) means for correcting said first power spectrum using at least one item selected from the group consisting of said first power spectrum, said second power spectrum, said third power spectrum, said fourth power spectrum, mean value of said first scatter detector signal, mean value of said second scatter detector signal, mean value of said third detector signal, mean value of said fourth detector signal, and total power in at least one frequency band for at least one of the group consisting of said first scatter detector signal, said second scatter detector signal, said third detector signal, and said fourth detector signal, to calculate a power spectrum of a particle scatter signal by correcting said first power spectrum to produce a corrected power spectrum which generally represents only a signal due to light scattered from particles of interest, wherein said correcting means does not consist of means for only subtracting said second power spectrum from said first power spectrum, and
j) means for calculating particle characteristics from said corrected power spectrum.
8. The apparatus of claim 1, including means for correcting a power spectrum of a signal from said detecting means, to improve a dynamic range of analog to digital conversion of an optical interference signal derived from light which is scattered from particles, comprising:
a) means for using said detector means to measure an optical interference signal, from at least one particle, as a function of time,
b) means for electronically filtering said optical interference signal to provide a filtered optical interference signal with a more uniform power spectrum,
c) means for converting said filtered signal from analog to digital form, to produce a digital sequence of signal values,
d) means for calculating a power spectrum of said digital sequence,
e) means for dividing said power spectrum by a power transmission of said electronic filtering, at each frequency, to produce a spectral corrected power spectrum,
f) means for using said spectral corrected power spectrum to calculate characteristics of particles.
9. The apparatus of claim 1, wherein said reflector is generally flat and positioned in a generally collimated portion of light from said illuminating means.
10. The apparatus of claim 1, wherein said reflector is generally flat and positioned in a plane which is generally optically conjugate to a light source in said illuminating means.
11. The apparatus of claim 1, wherein light from said illuminating means converges through at least one concave or convex surface, to form a focus which is generally coincident with a center of curvature of said surface, and wherein said scattered light passes through said surface.
12. The apparatus of claim 1, wherein light, which is incident on said particles, and a scattering angle, are oriented such that an effect of Doppler shift, due to particle settling, is reduced.
13. The apparatus of claim 1, wherein an optical flux of light propagating towards said illumination means is reduced by a quarter wave plate.
14. The apparatus of claim 1, wherein said beam splitting means consists of a fiber optic coupler.
15. The apparatus of claim 1, wherein said reflector is generally at a surface of an end of an optical fiber or in a plane which is generally optically conjugate to the end of an optical fiber.
16. An apparatus for determining particle characteristics comprising:
a) illuminating means for illuminating one or more particles,
b) detecting means for detecting light scattered from one or more detected particles, wherein scattered light is received by said detecting means from each detected particle,
c) a reflector for directing light from the illuminating means, by means of or through a beam splitting means, to the detecting means, wherein light from the reflector is combined with light scattered from one or more detected particles to produce an optical interference signal,
d) means for containing said particles, and
e) aperture means comprising means for controlling a size of a detector in said detecting means or an aperture which is positioned between a detector, in said detecting means, and said beam splitting means, wherein said aperture means controls properties of light received by a detector in said detecting means, and wherein said properties are selected from the group consisting of coherence properties and multiple scattering properties, and wherein said coherence property control increases a visibility of an optical interference signal, and wherein said multiple scattering property control reduces an amount of multiple scattered light received by said detector,
wherein the apparatus further comprises
a plurality of detecting means,
a plurality of beamsplitting means,
a plurality of reflectors, and
a plurality of aperture means,
wherein each detecting means measures scattered light, scattered from said particles, over a different range of scattering angles,
wherein scattered light passes through a window with generally spherical surfaces, said surfaces each having a center of curvature generally coincident with a focal point of light from said illuminating means.
17. An apparatus for determining particle characteristics comprising:
a) illuminating means for illuminating one or more particles,
b) detecting means for detecting light scattered from one or more detected particles, wherein scattered light is received by said detecting means from each detected particle,
c) a reflector for directing light from the illuminating means, by means of, or through, a beam splitting means, to the detecting means, wherein light from the reflector is combined with light scattered from one or more detected particles to produce an optical interference signal, and wherein said beam splitting means comprises a fiber optic coupler or beam splitter, and wherein light from said illuminating means is focused through a transparent portion of a wall of a removable andor replaceable container which holds the particles, and wherein a focal point of said light from said illuminating means is generally at said reflector which is a partially reflecting surface of said transparent portion of a wall, and wherein said surface contacts the dispersion of said particles, and
d) means for containing said particles consisting of a removable andor replaceable container.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An engine cooling fan shroud structure for a vehicle, comprising:
a skirt defining a frame, the frame having a certain wall thickness and defining an opening therein constructed and arranged to permit air to pass through the skirt, the skirt including motor mount structure supported in the opening and constructed and arranged for mounting a fan motor thereto, the frame defining passageways there-through reducing an amount of material of the skirt, and
a film material, having a wall thickness substantially less than the certain wall thickness, covering the passageways such that air may flow mainly through the opening.
2. The shroud structure of claim 1, wherein the frame is of generally box-like, rectangular shape.
3. The shroud structure of claim 1, wherein the skirt further includes an annular rim defining the opening, the motor mount structure being coupled to the annular rim by a plurality of arms.
4. The shroud structure of claim 3, wherein the passageways generally surround the annular rim.
5. The shroud structure of claim 4, wherein the passageways extend from sides of the skirt to the annular rim.
6. The shroud structure of claim 1, further comprising a plurality of bypass openings in the film material constructed and arranged to permit a certain amount of air to bypass the opening in the skirt.
7. The shroud structure of claim 1, wherein at least two layers of film material are provided, each layer having a plurality of bypass openings therein constructed and arranged to permit a certain amount of air to bypass the opening in the skirt, the bypass openings in one layer being disposed at a position different from a position of the bypass openings in the other layer, such that under low vehicle speed conditions, fan suction draws each layer together creating an airtight seal and under high speeds, ram air creates high pressure inside the shroud structure and forces the layers apart, allowing air to pass through the bypass openings.
8. The shroud structure of claim 1, wherein the skirt comprises injection molded thermoplastic.
9. The shroud structure of claim 1, wherein the film material comprises a plastic material.
10. The shroud structure of claim 1, wherein the film material comprises a paper material.
11. An engine cooling fan shroud structure for a vehicle, comprising:
a skirt defining a frame, the frame having a certain wall thickness and defining an opening therein constructed and arranged to permit air to pass through the skirt, the skirt including motor mount structure supported in the opening and constructed and arranged for mounting a fan motor thereto, the frame defining passageways there-through reducing an amount of material of the skirt, and
means for covering the passageways such that air may flow mainly through the opening,
wherein the skirt comprises injection molded thermoplastic and wherein means for covering is a film material comprised of a plastic material.
12. The shroud structure of claim 11, wherein the film material has a wall thickness substantially less than the certain wall thickness.
13. The shroud structure of claim 11, wherein at least two layers of film material is provided, each layer having a plurality of bypass openings therein constructed and arranged to permit a certain amount of air to bypass the opening in the skirt, the bypass openings in one layer being disposed at a position different from a position of the bypass openings in the other layer, such that under low vehicle speed conditions, fan suction draws each layer together creating an airtight seal and under high speeds, ram air creates high pressure inside the shroud structure and forces the layers apart, allowing air to pass through the bypass openings.
14. The shroud structure of claim 11, wherein the skirt further includes an annular rim defining the opening, the motor mount structure being coupled to the annular rim by a plurality of arms.
15. The shroud structure of claim 14, wherein the passageways generally surround the annular rim.
16. The shroud structure of claim 15, wherein the passageways extend from sides of the skirt to the annular rim.
17. The shroud structure of claim 11, further comprising a plurality of at least one bypass opening in the means for covering that is constructed and arranged to permit a certain amount of air to bypass the opening in the skirt.