Optical pressure/density measuring means

Patent · Tue May 09 04:00:00 EDT 1995

OSTI ID:869880

Veligdan, James T ^[1]

---

1. Manorville, NY

An apparatus and method for rapidly and accurately determining the pressure of a fluid medium in either a static or dynamic state. The pressure is determined by making a measurement of the velocity of a light beam that is directed through the fluid medium along a pathway that enables an integrated pressure measurement to be made along the pathway, rather than making such a measurement only at a single point in the medium. A HeNe laser is configured to emit a beam of two frequencies separated by about 2 MHz. One of these beam frequencies is directed through the fluid medium and is reflected back through the medium to a non-linear diode detector. The other beam frequency is passed directly to a diode detector without traversing said medium. The diode detector is operated to determine the frequency shift or beat frequency between the two beam frequencies. Any variation in the frequency of said reflected beam that is caused by a change in its velocity as it is passed through the fluid medium causes a change in the beat frequency. This beat frequency change is then converted to an output signal value corresponding to the pressure of the medium. The measurement instrument apparatus is remotely positioned relative to the medium being measured, thus the apparatus is immune from electro-magnetic interference and can operate in conditions of high radiation, corrosion and extraordinarily high temperature.

• Research Organization: ASSOC UNIVERSITIES INC
• DOE Contract Number: AC02-76CH00016
• Assignee: Associated Universities, Inc. (Washington, DC)
• Patent Number(s): US 5414509
• Application Number: 08/027,878
• OSTI ID: 869880
• Country of Publication: United States
• Language: English

Related Subjects

/356/
accurately
accurately determining
apparatus
beam
beam frequency
beat
beat frequency
caused
causes
change
conditions
configured
converted
corresponding
corrosion
density
detector
determine
determined
determining
diode
diode detector
directed
directly
dynamic
electro-magnetic
emit
enables
extraordinarily
fluid
fluid medium
frequencies
frequency
frequency change
frequency shift
hene
immune
instrument
integrated
interference
laser
light
light beam
linear diode
means
measured
measurement
measurement instrument
measuring
measuring means
medium
method
mhz
non-linear
operate
operated
optical
output
output signal
passed
passed directly
pathway
positioned
positioned relative
pressure
pressure measurement
radiation
rapidly
reflected
reflected beam
relative
remotely
separated
shift
signal
signal value
single
static
temperature
traversing
value
value corresponding
variation
velocity