Remote air detection
AssigneeMarconi Electronic Systems Limited
InventorsRoger M Langdon, Philip M Watts
Life of this patent
Estimating the term…
Abstract
A transmitter (41) is arranged to produce and focus a beam (54) on a remote focal point (55). A small proportion of resultant light (58) is back-scattered from the focal point (55) by particles or aerosols in air flowing through point (55) and returns to a receiver (42) where it is collected A detector combines resultant light (58) and reference light (72), splits the resultant light (58) and reference light (72) equally between two arms and detects which arm leads the other in phase thereby indicating the flow direction of air through focal point (55).
Claims20
An arrangement for determining air flow direction and velocity of air remote from an aircraft in flight, comprising:
- a) a transmitter on the aircraft, for focusing and directing a primary light beam to a focal region remote from the aircraft, and for generating a secondary light beam from the primary beam;
- b) a receiver on the aircraft, for converting return light scattered by the air at the focal region into a scattered light beam;
- and
- c) a detector for determining the air flow direction and the velocity of the air at the focal region, including
- i) a beam-splitter for splitting the scattered beam into first and second signal beams, and for splitting the secondary beam into first and second reference beams,
- ii) a polarizer for polarizing the signal beams to differ in phase by ninety degrees, and
- iii) a detection circuit for processing the first signal beam and the first reference beam to produce a first electrical signal having a first phase, for separately processing the second signal beam and the second reference beam to produce a second electrical signal having a second phase, for combining the first and second signals to determine the air velocity, and for processing the first and second phases to determine the air flow direction.
A method of determining air flow direction and velocity of air remote from an aircraft in flight, comprising the steps of:
- a) focusing and directing a primary light beam to a focal region remote from the aircraft, and generating a secondary light beam from the primary beam;
- b) converting return light scattered by the air at the focal region into a scattered light beam;
- and
- c) determining the air flow direction and the velocity of the air at the focal region, including
- i) splitting the scattered beam into first and second signal beams, and splitting the secondary beam into first and second reference beams,
- ii) polarizing the signal beams to differ in phase by ninety degrees, and
- iii) processing the first signal beam and the first reference beam to produce a first electrical signal having a first phase, separately processing the second signal beam and the second reference beam to produce a second electrical signal having a second phase, combining the first and second signals to determine the air velocity, and processing the first and second phases to determine the air flow direction.
Dependencies are inferred from the claim text.