Linear array focused-laser differential interferometry for single-shot multi-point flow disturbance measurements.

Area of Science:

• Optics and Photonics
• Fluid Dynamics
• Aerospace Engineering

Background:

• Focused-laser differential interferometry (FLDI) is a key technique for measuring fluid disturbances.
• Current multipoint FLDI systems often rely on complex and costly optical setups, such as multiple Wollaston prisms.
• There is a need for more efficient and cost-effective methods to increase the number of probed locations in FLDI.

Purpose of the Study:

• To demonstrate a modified focused-laser differential interferometer (FLDI) system capable of efficient multipoint measurements.
• To introduce a cost-effective alternative for generating multiple beams in FLDI systems.
• To enhance the throughput of FLDI measurements, particularly in aerospace testing.

Main Methods:

• A diffractive optical element was employed to generate multiple beams within the FLDI system.
• Measurements were initially performed using a 1D linear array of points.
• A 2D array capability was demonstrated by using two linear diffractive optical elements in tandem, creating the linear array FLDI (LA-FLDI).

Main Results:

• The novel diffractive optical element approach proved significantly more cost-effective and easier to implement than traditional methods.
• The linear array FLDI (LA-FLDI) successfully provided measurements of fluid disturbances at multiple discrete locations.
• High data acquisition rates exceeding 1 MHz were maintained with the LA-FLDI system.

Conclusions:

• The developed linear array FLDI (LA-FLDI) offers a simpler and more efficient method for multipoint interferometric measurements.
• This technique can substantially increase the throughput of FLDI measurements in demanding environments like impulse aerospace testing facilities.
• The use of diffractive optical elements presents a scalable and economical solution for advanced fluid dynamics research.