US 5,333,044 A · Fluorescent image tracking velocimeter

Abstract

A multiple-exposure fluorescent image tracking velocimeter (FITV) detects and measures the motion (trajectory, direction and velocity) of small particles close to light scattering surfaces. The small particles may follow the motion of a carrier medium such as a liquid, gas or multi-phase mixture, allowing the motion of the carrier medium to be observed, measured and recorded. The main components of the FITV include: (1) fluorescent particles; (2) a pulsed fluorescent excitation laser source; (3) an imaging camera; and (4) an image analyzer. FITV uses fluorescing particles excited by visible laser light to enhance particle image detectability near light scattering surfaces. The excitation laser light is filtered out before reaching the imaging camera allowing the fluoresced wavelengths emitted by the particles to be detected and recorded by the camera. FITV employs multiple exposures of a single camera image by pulsing the excitation laser light for producing a series of images of each particle along its trajectory. The time-lapsed image may be used to determine trajectory and velocity and the exposures may be coded to derive directional information.

Claims17

Dependent claims

Apparatus for determining the flow field of a fluid near a fluid confining wall of a transparent body, said apparatus comprising:

a plurality of neutrally buoyant fluorescent particles suspended in the fluid;
a source of pulsed monochromatic light for directing a monochromatic light beam on the fluid and the confining wall for illuminating said fluorescent particles at predetermined time intervals, wherein said monochromatic light beam has a frequency .lambda..sub.1 capable of exciting said particles to a pulsed state of fluorescence at a frequency .lambda..sub.2 ;
filter means for receiving light scattered from said confining wall having said frequency .lambda..sub.1 and said fluorescent light having said frequency .lambda..sub.2 and for removing said scattered light and passing said fluorescent light;
and
optical means cooperating with said filter means for receiving pulsed fluorescent light from said excited fluorescing particles having a frequency .lambda..sub.2 and for tracking displacement of said fluorescent particles in the fluid over time in providing a velocity map of said particles in the fluid adjacent to the confining wall of the body.

2 more elements

Dependencies are inferred from the claim text.

Fluorescent image tracking velocimeter

Life of this patent

Fluorescent image tracking velocimeter

Life of this patent

Abstract

Claims17