PIV

PIV (Particle Image Velocimetry) technology is a non-contact, instantaneous, dynamic, full-flow velocity field measurement technology. This technology uses optical methods to carry out flow measurement and structure research inside the airflow and liquid flow field, which is a development achievement of the traditional flow display technology.PIV system mainly contains four parts, including timing controller, computer and PIV application software, image recorder, optical illumination system, etc., of which the optical illumination system usually chooses the green pulsed solid-state lasers.

Laser Illumination for PIV Measurements

PIV is a non-intrusive optical technique used to measure instantaneous velocity distributions across a flow field. Tracer particles are introduced into the gas or liquid and illuminated twice by a laser sheet with a controlled time interval, Δt. A synchronized camera records the particle positions in two consecutive frames, and PIV software calculates the velocity vectors from their displacement.

The laser is therefore a critical part of the measurement chain. Pulse energy determines whether sufficient scattered light reaches the camera, while pulse duration, timing jitter, beam overlap and light-sheet uniformity directly affect image sharpness and correlation quality.

Beamtech focuses on the PIV laser source, beam delivery, light-sheet formation and synchronization interface. Cameras, timing controllers, seeding equipment and processing software can be integrated according to the interfaces and configuration of the customer’s existing PIV system.

The Vlite series, including the Vlite-Hi-100 and Vlite-Hi-527 models, consists of dual-pulse lasers specifically designed for various 2D/3D PIV, Tomographic PIV, and Time-resolved PIV applications. As a manufacturer with extensive experience in developing and producing specialized PIV lasers, Beamtech Optronics Co., Ltd. has supplied users with hundreds of PIV laser products that have been applied in such fields as high-speed flow, marine biology, aerodynamics, aviation, and combustion.

Beamtech Optronics Co., Ltd. has accumulated a wealth of engineering and technical experience. Its products incorporate beam homogenization technology to ensure high beam quality, meeting the importance of uniform beam distribution for PIV applications. Other engineering and technical details include an integrated cast housing, 7-joint movable light guide arm, and the stability of the dual-beam combination, ensuring long-term stable use and reliability.

For Tomo PIV and Time-resolved PIV, the high-energy PIV models Vlite-380/500 and the high repetition rate of Vlite-Hi-527 models are well-suited to meet the requirements. Additionally, Beamtech Optronics Co., Ltd. can provide customized PIV laser systems based on customers’ application needs, offering comprehensive solutions.

The appropriate laser configuration depends on the measurement area, flow velocity, camera acquisition rate, tracer particles, optical access and required temporal resolution.

Available pulse energy may vary with repetition rate and final system configuration. Beamtech engineers can recommend a suitable model after reviewing the experimental conditions.

Pulse Energy and Measurement Area

A larger field of view generally requires more laser energy to maintain sufficient particle-image intensity across the illuminated region. Energy requirements are also affected by seeding concentration, particle size, camera sensitivity, light-sheet thickness, optical losses and the transparency of the test medium.

Ultra-high-energy systems such as the Vlite-1000 are intended for large measurement areas and tomographic PIV, while lower-energy, higher-frequency lasers are more suitable for time-resolved measurements.

Repetition Rate and Flow Dynamics

Low-repetition-rate dual-pulse lasers are suitable for statistically sampled or relatively stable flow fields. Measurements of turbulence, vortex development, spray evolution and other rapidly changing processes require a higher repetition rate so that consecutive velocity fields can be resolved over time.

The Vlite-Hi-100 supports measurements at 100 Hz, while the Nd Vlite-Hi-527 extends the acquisition rate into the kHz range for time-resolved PIV.

Pulse Width and Synchronization

Short laser pulses help freeze particle motion and reduce image streaking in high-speed flows. Stable timing between the two laser cavities is also necessary because the calculated velocity depends on the accurately controlled pulse separation.

Selected Beamtech Vlite configurations provide timing jitter below 1 ns, supporting precise synchronization with external cameras and PIV timing controllers.

Beam Uniformity and Light-Sheet Quality

Uneven illumination produces differences in particle-image intensity across the field of view and can reduce the quality of cross-correlation results. Beamtech applies beam homogenization and stable dual-cavity beam-combination designs to produce a more consistent illumination profile.

Integrated articulated beam-delivery arms and light-sheet optics are available for directing the laser into the test section while reducing repeated alignment work.

Wind Tunnel and Aerodynamic Testing

PIV allows researchers to visualize boundary layers, wakes, vortices and separated flows around aircraft models, vehicles, turbines and other aerodynamic structures. High pulse energy is beneficial for large wind-tunnel windows, while higher repetition rates are required when transient aerodynamic structures must be resolved.

Water Channels and Hydrodynamics

Dual-pulse PIV lasers can be used to study flow around marine structures, propellers, pumps, hydraulic components and biological subjects. The required energy depends on the measurement area, water quality, particle scattering and the distance between the laser and test section.

Combustion and Spray Diagnostics

Combustion chambers, fuel sprays and atomization processes often combine rapid motion with strong background radiation. Narrow laser pulses, appropriate repetition rates and carefully selected optical filters help separate particle-scattered light from flame luminosity and background emissions.

Turbulence and Time-Resolved Flow Measurement

High-repetition-rate PIV captures sequences of velocity fields rather than isolated image pairs. This makes it possible to analyze vortex evolution, flow instability, acceleration and other transient phenomena that cannot be fully described using low-frequency measurements.

Tomographic and Large-Volume PIV

Tomographic PIV requires sufficient illumination throughout a three-dimensional measurement volume observed by multiple cameras. High-energy models such as the Vlite-1000 provide additional illumination capacity for large fields and volume measurements where optical losses are greater.

Beamtech PIV lasers are engineered to support long-duration laboratory and testing work through:

• ◆  Stable combination of two independently triggered laser cavities;

• ◆  Uniform beam distribution designed for PIV illumination;

• ◆  Thermally stable resonator structures on applicable models;

• ◆  Integrated laser head, articulated beam-delivery arm and light-sheet optics;

• ◆  External triggering for synchronization with cameras and timing controllers;

• ◆  Water-cooling, flow monitoring and equipment protection for high-power models;

• ◆  Protective shutters, interlocks and emergency-stop functions on applicable Class IV systems.

The Vlite-Hi-527 series also incorporates safety and electromagnetic compatibility measures and has held CE certification since 2020.

Beamtech has developed solid-state laser systems since 2002 and has supplied PIV laser products for aerodynamics, combustion, high-speed flow, hydrodynamics and scientific research.

Our PIV laser development focuses on the factors that affect experimental repeatability: beam uniformity, dual-cavity alignment, timing stability, mechanical rigidity and practical beam delivery. Customers can select from standard Vlite configurations or discuss a project-specific laser and optical arrangement with our engineering team.