System for acquiring an image of a multi-phase fluid by measuring backscattered light

• US 5,815,264 A
• Filed: 04/07/1997
• Issued: 09/29/1998
• Est. Priority Date: 09/21/1994
• Status: Expired due to Term

• Current Assignee: Mettler-Toledo Autochem, Inc. (Mettler-Toledo International Inc.)
• Original Assignee: Laser Light Technologies, Inc.
• Inventors: Montague, Thomas W., Hamann, Oliver S., Hokanson, Jon V., Reed, Barry W.
• Primary Examiner(s): Rosenberger, Richard A.
• Application Number:
  US08/835,188
• Time in Patent Office: 540 Days
• Field of Search: 356/336, 356/338, 356/342, 356/343, 250/574
• US Class Current: 356/336
• CPC Class Codes: G01N 15/0205 by optical means
• CPC Class Codes: G01N 21/53 within a flowing fluid, e.g. smoke

Abstract

An in-situ imaging system suitable for analyzing particles or droplets contained in process reactor vessels or pipelines at full process concentrations is disclosed. The system includes a light source capable of high peak power output operated in a pulsed mode that is located inside of a probe. The light from the light source is coupled into an optical fiber. The light is carried by the optical fiber to a lens system near the end of the probe which focuses the light through a window to the area which coincides with the field of view in the focal plane of the imaging optics. The imaging optics collect the light which is back-scattered from particles or droplets, magnifying the image and projecting it onto an image detector such as a CCD array.

Claims

1. An apparatus for providing an image of a fluid medium, the apparatus comprising:

a probe for insertion into said fluid medium, said probe including a window at the tip of said probe, and said probe adapted for placement in said fluid medium such that said window is disposed at an insertion angle to a direction of flow of said fluid medium;

a light source for generating an illuminating light;

a light transmission system for transmitting said illuminating light from said light source to said window, said light transmission system including focusing lens means for focusing said illuminating light onto a focal plane in said fluid medium;

an image detector;

a processor; and

an optical system for collecting backscattered light from said fluid medium over a collection angle to form an optical image of said fluid medium, said optical system having a focal plane substantially the same as the focal plane of said illuminating light, wherein said optical system using said light transmission system for relaying the optical image to said image detector and said processor such that said image detector and said processor are operative to generate said image.

2. The apparatus of claim 1, wherein the probe includes means to move the focal plane of said image acquiring means relative to the surface of the window, without changing the focal length or magnification of the optical system and keeping the spatial relationship between the illumination system and the optical system constant.

3. The apparatus of claim 1, where said light source consists of a pulsed laser diode.

4. The apparatus of claim 1, where said optical system for collecting the backscattered light includes a magnifying lens system.

5. The apparatus of claim 1, where the light transmitting system is a fiber optic cable and said light transmitting system includes focusing optics to focus the illuminating light from said light source into one end of a fiber optic cable.

6. The apparatus of claim 1, where said optical system for collecting said backscattered light consists of an imaging lens.

7. The apparatus of claim 1, where the probe is adapted to have an insertion angle between 30°

to 45°

.

8. The apparatus of claim 1, where the backscattered light goes through an optical shutter, said optical shutter only open for the duration of the illuminating light.

9. An apparatus for providing an image of a fluid medium, the apparatus comprising:

a probe for insertion into said fluid medium, said probe including a window at the tip of said probe, and said probe adapted for placement in said fluid medium such that said window is disposed at an insertion angle to a direction of flow of said fluid medium;

a light source for generating an illuminating light;

a light transmission system for transmitting said illuminating light from said light source to said window, said light transmission system including focusing lens means for focusing said illuminating light onto a focal plane in said fluid medium;

a CCD array;

a processor; and

an optical system for collecting backscattered light from said fluid medium over a collection angle to form an optical image of said fluid medium, said optical system having a focal plane substantially the same as the focal plane of said illuminating light, wherein said optical system using said light transmission system for relaying the optical image to said CCD detector and said processor such that said CCD array and said processor are operative to generate said image.

10. The apparatus of claim 9, where said CCD array includes a storage array for storing said optical image and for allowing short exposure integration times.

11. A method of generating an optical image of a fluid medium, the method comprising the steps of:

inserting a probe into said fluid medium, said probe including a window at the tip of said probe, said probe inserted at an insertion angle to a direction of flow of said fluid medium;

generating an illuminating light;

transmitting and focusing said illuminating light through the window into said fluid medium such that said illuminating light is focused at a focal plane onto said fluid medium;

collecting backscattered light over a collection angle from said fluid medium using a set of collection optics;

focusing said backscattered light from said focal plane onto an image detector to form said optical image of said fluid medium on said image detector; and

relaying said optical image to an image processor.