Patent ID: 6700652
Filing Date: 2004-03-02
Classification: G01P

Abstract:
An apparatus for velocity measurement of particles in a particle-seeded particle flow field, said apparatus comprising:a continuous Argon ion laser emitting both continuous wave blue and continuous wave green beams of light; a color alternating laser sheet producer receiving said continuous wave blue and continuous wave green beams of light from said argon laser and outputting only a single laser sheet that is comprised of alternating pulses of blue and green light, said particle-seeded flow field being illuminated by only said single laser sheet of alternating pulses of blue and green light; a photomultiplier with beam splitter receiving a green pulsed beam used in the production of said laser sheet; a CCD (charge coupled device) receiving and recording images, said single laser sheet illuminating said particle-seeded flow field, said single laser-sheet being output from said color alternating laser-sheet producer; and a computer programmed and configured to calculate, via cross-correlation analysis, the velocity of particles in the particle flow field from the recorded images of said particle flow field illuminated by said single laser sheet, said color alternating laser sheet producer comprising: an intermittent beam chopper converting said blue and said green continuous wave beams of light from said argon laser into beams of alternating blue and green pulses; a beam combinator receiving said beams of alternating blue and green pulses and combining them into a single beam; and a color alternating laser sheet generator receiving said single beam and converting said single beam into said single laser-sheet, said intermittent beam chopper comprising a variable-speed motor and a perforated multi-opening beam chopper plate that has an inner and an outer circumference, each circumference having three sets of perforations, said perforated multi-opening beam chopper plate producing said beams of alternating blue and green pulses from said blue and green continuous wave beams of light when said blue and green continuous wave beams of light illuminate said perforated chopper plate when said perforated chopper plate rotates.