Photodensitometer for minimizing the refractive effects of a fluid sample
First Claim
1. A photometric method for minimizng the optical effect of a meniscus on a fluid sample, comprising the following steps:
- generating light from a light source;
collecting the generated light and forming a light beam having a central optical axis;
focusing the light beam to form a vertical cone of light; and
axially positioning the meniscus of a fluid sample substantially at the narrowest portion of the light cone so that a central portion of the meniscus illuminated by the light cone has a minimal refractive effect on the light beam.
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Accused Products
Abstract
An automated vertical photo densitometer for reading solutions contained in microwell plates. The densitometer utilizes an optical system for minimizing the optical effect of a meniscus on the fluid sample. The invention also discloses a method for determining a centrally located position of a microwell beneath an interrogating beam of light by controlling the size of the light beam and by stepping the well through the beam. A measurement of the light intensity received by a detector is taken at each step. A maximum light intensity value is selected as corresponding to a well position wherein a central area of the fluid sample is substantially within the interrogating beam.
59 Citations
39 Claims
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1. A photometric method for minimizng the optical effect of a meniscus on a fluid sample, comprising the following steps:
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generating light from a light source; collecting the generated light and forming a light beam having a central optical axis; focusing the light beam to form a vertical cone of light; and axially positioning the meniscus of a fluid sample substantially at the narrowest portion of the light cone so that a central portion of the meniscus illuminated by the light cone has a minimal refractive effect on the light beam. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A vertical photometer for measuring an optical characteristic of a fluid sample having a meniscus and for minimizing the optical effect of the meniscus, comprising:
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a light source; means for collecting light from the light source to form a light beam defining an optical axis; means for positioning a central portion of a meniscus on a fluid sample substantially perpendicular to the optical axis; and means for focusing the light beam to define a cone of light having a reduced diameter portion at the central portion of the meniscus so that refraction of the beam by the meniscus is minimized. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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32. A photometric method for substantially locating a vertical light beam within a central portion of a fluid well bottom wherein the fluid well has a coordinate position on a plate having a known manufacturing variance, comprising the following steps:
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selecting a beam diameter at the well bottom smaller than the well bottom diameter; grossly positioning the plate so that the center of the well is positioned transverse to a radial path through the axis of the light beam within a predetermined tolerance which is smaller than the well bottom radius less the beam radius; using a plate having a manufacturing variance for the coordinate position of the well which is less than the predetermined tolerance; and moving the beam and plate relative to one another along a parallel path to the radial path and within the predetermined tolerance so that all of the beam passes through the well bottom at some point on the parallel path. - View Dependent Claims (33)
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34. A photometric method for measuring the optical density of a fluid sample, comprising the following steps:
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containing the fluid sample in a fluid well having an open top and a substantially transparent bottom; forming a light beam having a central optical axis; focusing the light beam to provide a substantially narrowed portion thereof; grossly positioning the center of the well transverse to a radial path through the optical axis within a predetermined tolerance; axially positioning the well in a radial plane such that a central portion of a fluid meniscus on the fluid sample can be illuminated by the substantially narrowed portion of the focused beam to minimize refraction of the beam by the meniscus; and moving the beam and well relative to one another along a parallel path to the radial path in discrete steps so that all of the beam passes through the well bottom at some point on the parallel path. - View Dependent Claims (35)
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36. A method for determining a central location of a light beam within a well having upwardly projecting sidewalls and a substantially flat, transparent portion, comprising the following steps:
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moving the light beam and the well relative to one another along a path such that all of the beam passes through the transparent portion at some point on the path; measuring the intensity of the light transmitted through the substantially transparent portion; detecting a maximum intensity measurement; and
associating the detected maximum with a central beam location wherein all of the beam has passed through the substantially transparent portion. - View Dependent Claims (37, 38)
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39. A method for determining the HLA type of cells, comrprising the following steps:
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introducing a human leukocyte suspension into a plurality of wells having open tops and substantially transparent bottom portions wherein the wells are coated to enhance the binding of the leukocytes to the wells; centrifuging the cell-containing wells thereby forming supernatant; removing the supernatant and washing the cell-containing wells; adding monoclonal antibody specific for an alloantigen into at least one well, wherein differing monoclonal antibodies are put in different wells resulting in the formation of monoclonal antibody/cell complexes; washing the wells to remove nonspecifically bound monoclonal antibody; adding antibody conjugated with an enzyme or a receptor conjugated to an enzyme which binds to the monoclonal antibody/cell complexes; adding a colorimetric substrate to the wells to provide a fluid sample having an absorption maxima at a specific wavelength, wherein the optical density of the fluid sample at the wavelength is proprotional to the degree of formation of antigen-antibody complexes; generating a light from a light source substantially at the wavelength; collecting the generated light and forming a light beam havng a central optical axis; focusing the light beam to form a vertical cone of light; axially positioning the meniscus of the fluid sample substantially at the narrowest portion of the light cone so that a central portion of the meniscus illuminated by the light cone has a minimal refractive effect on the light beam; moving the light beam and the transparent portion relative to one another along a path such that all of the beam passes through the transparent portion at some point on the path; measuring the intensity of the light transmitted through the substantially transparent portion; and detecting the light transmitted through the fluid sample and therefrom determining the HLA types of the cells.
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Specification