3D laser vibrometers for vibration measurements in x, y and z.

3D scanning for spatial vibration patterns

Three synchronized scanning vibrometers simultaneously measure each defined surface point from different directions. SMART Lab calculates x, y, and z from these signals and then moves to the next measurement point. This makes it possible to spatially identify bending and torsional components as well as in-plane and out-of-plane motion, and compare them with simulation data.

Typical applications:

• Operating deflection shape analysis (ODS) and NVH: Analyze spatial vibration patterns, local vibration maxima, and coupled bending, torsional, in-plane, and out-of-plane components.
• Experimental modal analysis (EMA): Determine natural frequencies, damping, and three-dimensional mode shapes based on a measured excitation.
• FEM correlation, model validation and model updating: Compare measurement and simulation data in the same coordinate system and at corresponding nodes. The measurement data can then be used to adjust material parameters, joints, mountings, and boundary conditions.
• Evaluate measures: Verify the effects of geometry changes, damping measures, or modified boundary conditions through comparative measurements.

Requirement: The vibration must be stationary or reproducible during the scan. A reference signal phase-aligns the points measured sequentially.

3D-Single-Point for continuous 3D measurements

Three lasers remain focused on the same point throughout the measurement. Each measurement direction captures the motion component along its laser axis. The hardware continuously transforms the three measurement signals into x, y, and z and provides the components synchronously at the digital and analog outputs.

Typical applications:

• Transient and non-repeatable events: Capture the complete three-dimensional motion during impact, switching, run-up, or decay events.
• Process monitoring: Analyze directions of motion in machining processes, for example to investigate chatter vibrations or unstable process conditions.
• Small and lightweight components: Measure MEMS, printed circuit boards, electronic components and thin-walled structures where a triaxial accelerometer would affect the result due to its mass.
• Sensor and actuator testing: Non-contact measurement of the three-dimensional motion of small sensors, accelerometers, actuators or transducers.
• Hot or sensitive surfaces: Measure in three dimensions when sensor mounting is unsuitable due to temperature, material properties or surface sensitivity.

Requirement: All three lasers require an unobstructed line of sight to the measurement point.

Scope: This method provides the complete motion profile at a single point, but not a spatially resolved mode shape.

What does a 1D laser vibrometer measure?

A 1D laser vibrometer measures vibration velocity or displacement along its laser axis. It therefore captures one component of motion, but not the complete direction of motion in x, y and z.

A 1D scanning vibrometer automatically repeats this measurement at many points on a surface. This creates a spatially dense measurement grid, but only one directional component is still captured at each point.

When is a 1D vibration measurement sufficient?

A 1D measurement is suitable when the relevant motion occurs predominantly in a known direction. A typical example is vibration analysis of thin body panels. Their bending vibrations are often primarily perpendicular to the local surface, i.e. Out-of-plane. If the panel is targeted approximately perpendicular to the laser beam, a 1D scanning vibrometer captures the relevant motion component at many points and visualizes its spatial distribution.

If tangential motions, coupled bending and torsional components, or the complete motion in x, y and z are also to be investigated, a 3D measurement is advisable.

Why the measurement angle matters

When the laser beam strikes a flat surface perpendicularly, it captures only the motion component normal to the surface, i.e. Out-of-plane. If the surface is targeted at an angle, components of Out-of-plane and In-plane motion contribute to the same measurement signal. A single laser cannot distinguish between these components.

On curved surfaces, the measurement angle changes from point to point. Therefore, multiple measurement directions are required if the motion is to be unambiguously separated into x, y and z.

How x, y and z are determined

For 3D measurement, three lasers simultaneously capture the same surface point from different measurement directions. Because the spatial orientation of the lasers is known and calibrated, the three measurement signals can be transformed into the x, y and z components.

This allows In-plane and Out-of-plane motions, or radial, tangential and axial vibration components, to be evaluated separately. In 3D scanning, this measurement is automatically repeated at all defined points on the surface.

1D and 3D at a glance

• 1D-Single-Point: One directional component at a fixed measurement point.
• 1D-Scanning: One directional component at many sequentially measured points.
• 3D-Single-Point: x, y and z simultaneously and continuously at a fixed measurement point.
• 3D-Scanning: x, y and z simultaneously at each measurement point; the surface is captured point by point.
• Key point: More measurement points increase spatial resolution. Only additional measurement directions enable separation into x, y and z.

Optomet systems for 3D vibration measurement

Optomet implements both measurement methods with systems from the SMART series. SMART 3D-Scan captures x, y and z across a defined component surface. SMART 3D-Fiber continuously measures the three components at a fixed point. Both systems operate without contact and can be integrated into SMART Lab or existing measurement chains.

SMART 3D-Scan: automatically capture three-dimensional operating deflection shapes

SMART 3D-Scan combines three synchronized SMART Scan+ vibrometers. At each defined measurement point, all three instruments capture the same surface point simultaneously from different directions. SMART Lab calculates x, y and z from these data and then moves to the next measurement point. This automatically captures the entire defined measurement area.

• Result: Spatially resolved operating deflection shapes with separate x, y and z components. With a measured excitation, three-dimensional mode shapes can also be determined from an experimental modal analysis.
• Seamless workflow: Import a CAD or FEM model, define measurement points, calibrate the system, start the scan and evaluate the results – all steps remain within a single SMART Lab project.
• Modular design: Each SMART Scan+ can also be used independently as a complete 1D scanning vibrometer. Existing systems can be expanded to 3D or into larger synchronized measurement setups.
• Typical tasks: operational vibration analysis, experimental modal analysis, NVH, FEM correlation, model validation and Model Updating.

View SMART 3D-Scan | SMART 3D-Scan data sheet (PDF)

SMART 3D-Fiber: continuously measure x, y and z at a single point

With SMART 3D-Fiber, three laser beams remain aligned with the same surface point throughout the entire measurement. The device hardware continuously transforms the three measurement signals into x, y and z and provides the components synchronously at the digital and analog outputs. This captures the complete three-dimensional motion at that point.

• Temporal behavior: Suitable for continuous, rapidly changing, one-time and non-repeatable processes.
• Typical tasks: process monitoring, investigation of small and lightweight components, PCB and electronics testing, and testing of sensors, actuators and transducers.
• Integration: Use with SMART Lab or output of the synchronous x, y and z signals to an external data acquisition system.
• Alignment: An integrated camera helps align the three lasers to the same point. All three lasers require a clear line of sight to the measurement point.

View SMART 3D-Fiber | SMART 3D-Fiber data sheet (PDF)