OPTICAL SENSING SAMPLING HEAD

• US 3,787,703 A
• Filed: 05/25/1972
• Issued: 01/22/1974
• Est. Priority Date: 05/25/1972
• Status: Expired due to Term

• Current Assignee: George J. Topol
• Original Assignee: George J. Topol
• Inventors: Topol, George J.
• Primary Examiner(s): Dixon, Harold A.
• Application Number:
  US05/256,821
• Time in Patent Office: 607 Days
• Field of Search: 250/218,231
• US Class Current: 250/574
• CPC Class Codes: G01N 21/8507 Probe photometers, i.e. with optical measuring part dipped into fluid sample

Abstract

An optical sensing head which can be used with a probe and immersed in fluids and which operates to detect direct and refracted light transmission characteristics of the fluid and provide electrical signals representative thereof for further analysis. The apparatus includes a glass tube surrounded by an opaque cylindrical body having compartments to hold a light source and two photocells. The source and photocells lie in the same plane which is transverse with respect to the tube axis. An occluding pin is non-centrally disposed within the tube and is spaced from the interior walls of the tube. The body which holds the photocells and light source has openings which permit light from the source to illuminate the interior of the tube and which permits the photocells to sense light coming from within the tube, substantially all ambient light being excluded by the opaque body. The angular relationship of the openings to the photocells and source is critical, the path between one photocell and the light source being in a direct line with the occluding pin so that no light can pass directly from the source to that photocell. The other photocell, however, is disposed so that there is a direct linear light path between the source and that photocell. Thus, one cell receives direct light transmission and the other cell receives light only as a result of reflection and refraction by a fluid placed in the space in the plane containing the photocells. The apparatus includes a piston which surrounds the occluding pin within the tube and which is mounted for reciprocating movement therein to alternately block and unblock the light paths, draw fluid samples into the tube and then expel the samples, and to wipe the interior of the tube and the exterior of the occluding pin clean with sealing rings carried by the piston on each reciprocating motion. In a preferred embodiment the head is mounted on an elongated cylindrical housing so that it can be immersed to any desired depth in a body of fluid and can be cyclically driven to monitor the light transmission characteristics of the fluid while immersed.

Claims

1. An apparatus for measuring the light transmission characteristics of a fluid comprising the combination of a glass tube having at least one open end;

a generally tubular opaque body surrounding the tubular surface of said tube, said body having openings to receive a light source and two photocells, and transparent wall portions adjacent said openings to conduct light between said openings and the glass tube, said transparent wall portions being in the same plane, which plane extends generally transversely of the axis of said tube;

an elongated opaque member fixedly mounted and extending longitudinally within said tube, said elongated member being spaced from the inner walls of said tube in the vicinity of the plane containing said wall portions, and being positioned to block the light path between the wall portions adjacent the light source and one photocell but allow an essentially unobstructed light path to exist between the wall portions adjacent the light source and the other photocell; and

a piston movable longitudinally of said glass tube into and out of said plane containing said transparent wall portions to draw samples of fluid through said open end of said glass tube and into and out of said plane containing said transparent wall portions.

2. An apparatus according to claim 1 wherein said piston surrounds said elongated opaque member, and is provided with internal and external sealing members which contact the exterior surface of said opaque member and the interior surface of said tube for the dual purposes of drawing fluid into the tube and wiping said surfaces clean in the vicinity of said plane.

3. An immersible probe for measuring the transmission and refraction properties of fluids comprising a tubular body having at least one open end;

an opaque pin fixedly mounted in said tubular body, said pin having an axis parallel with the axis of said tubular body;

a piston disposed within said tubular body, and surrounding said pin, said piston being longitudinally movable relative to said tubular body and said pin to draw fluid into said tubular body from said one open end;

a first light transmissive wall portion in said tubular body;

a source of light mounted adjacent said first wall portion radially outwardly of said tubular body;

a seconD light transmissive wall portion located approximately diametrically opposed to said first wall portion;

a first photocell disposed adjacent said second wall portion and radially outwardly of said tubular body in a position to receive direct light transmission from said source;

a third light transmissive wall portion disposed on a line through said light source and perpendicular to said pin; and

a second photocell disposed adjacent said third wall portion and radially outwardly of said tubular body, said third portion and said pin being dimensioned and disposed to prevent direct light transmission from said source to said second photocell, said photocells being shielded by said tubular body to limit the light received by said first photocell to light from said source, and to limit the light received by said second photocell to light refracted by fluid drawn into said tubular body.

4. A probe according to claim 3 and further comprising drive means for cyclically reciprocating said piston between a location in which light passage from said source to said photocells is blocked by the piston and a location in which light passage is not blocked thereby.

5. An immersible probe for measuring the transmission and refraction properties of fluids comprising a cylinder having a longitudinal cylindrical bore extending inwardly from one end of the cylinder;

an opaque pin mounted in said bore, said pin having an axis parallel with the axis of said cylinder;

a piston disposed within said bore and surrounding said pin, said piston being longitudinally movable relative to said cylinder and said pin to draw fluid into said bore;

a first light transmissive wall portion in said cylinder;

a source of light mounted adjacent said first wall portion radially outwardly of said bore;

a second light transmissive wall portion located approximately opposite said first wall portion;

a first photocell disposed adjacent said second wall portion and radially outwardly of said bore in a position to receive direct light transmission from said source;

a third light transmissive wall portion disposed on a line through said light source and said pin;

a second photocell disposed adjacent said third wall portion and radially outwardly of said bore, said third portion and said pin being dimensioned and disposed to prevent direct light transmission from said source to said second photocell, said photocells being shielded to limit the light received by said first photocell to light from said source, and to limit the light received by said second photocell to light refracted by fluid drawn into said bore; and

drive means for cyclically reciprocating said piston between a location in which light passage from said source to said photocells is blocked by the piston and a location in which light passage is not blocked thereby, and wherein said piston carries means for wiping the exterior of said pin and the inner surfaces of said transmissive wall portions during each reciprocation.

6. An apparatus for measuring the light transmission characteristics of a fluid comprising the combination of a glass tube open at at least one end;

a generally tubular opaque body surrounding said tube, said body having openings to receive a light source and two photocells, and transparent wall portions adjacent said openings to conduct light between said openings and the glass tube, said wall portions being in the same plane, which plane extends generally transversely of the axis of said tube;

an elongated opaque member fixedly mounted longitudinally in said tube in a position offset from the longitudinal axis of said tube, said elongated opaque member being spaced from the inner walls of said tube in the vicinity of said openings, and said elongated opaque member being positioned to block the light path between the wall portions adjacent the light source and one photocell but allow an essentially unobstructed light paTh to exist between the wall portions adjacent the light source and the other photocell; and

means for causing samples of fluid to move into and out of the portion of said tube adjacent said tranparent wall portions.

7. An apparatus for measuring the light transmission characteristics of a fluid comprising the combination of a glass tube having at least one open end;

a generally tubular opaque body surrounding said tube, said opaque body having openings to receive a light source and two photocells, and transparent wall portions adjacent said openings to conduct light between each of said openings and said glass tube, all of said transparent wall portions being in the same plane which extends generally transversely of the axis of said glass tube;

an elongated opaque member fixedly mounted longitudinally in said glass tube in a position offset from the longitudinal axis of said tube, said elongated opaque member being spaced from the inner walls of said glass tube in the vicinity of said openings, and being positioned to block the light path between the transparent wall portions adjacent said light source and one photocell, but allow an essentially unobstructed light path to exist between the wall portions adjacent the light source and the other photocell; and

a piston located in said tube and movable longitudinally thereof into and out of the plane containing said transparent wall portions for drawing samples of fluid through said open end of said glass tube and into and out of the plane containing said transparent wall portions.

8. An apparatus according to claim 7 wherein said piston surrounds said opaque member and is provided with internal and external sealing members which contact the exterior surface of said opaque member and the interior surface of said tube for wiping said surfaces clean in the vicinity of said plane.

9. An apparatus for measuring the light transmission characteristics of a fluid comprising the combination of an opaque member having a cylindrical bore extending inwardly from one end of said member;

a transparent tube mounted in said bore, said tube having an outer diameter equal to the inner diameter of said bore and an open and adjacent the end of said bore;

a light source mounted in said opaque member;

means defining a passageway in said opaque member for permitting light from said light source to pass through the wall of said transparent tube and into said tube;

two photocells mounted in said opaque member on an opposite side of the longitudinal axis of said tube from said light source, said photocells being angularly spaced from each other, and said photocells and said light source being contained in a plane generally transverse to the longitudinal axis of said tube;

means defining two additional passageways in said opaque member for permitting light from the inside of said tube to pass through said tube and illuminate said photocells;

opaque means, fixedly supported and extending longitudinally in said transparent tube, for permitting light emanating from said light source to directly illuminate one of said photocells and for preventing light emanating from said light source to directly illuminate the other of said photocells but permitting refracted light to illuminate the other of said photocells;

piston means, mounted for reciprocal longitudinal movement in said tube, for drawing fluid into and expelling fluid from said tube through said open end and moving the fluid into and out of the plane containing said light source and said photocells, said piston having means defining a cavity therein for the reception of a portion of said opaque means whereby said piston means can move along said opaque means.