White Light Interferometer: A Precision Tool for Engineers in Surface Metrology

Wafer micropattern (2500×)

Unlike stylus-based profilometers that make physical contact with the surface, WLIs operate entirely optically, eliminating the risk of surface damage while enabling faster, higher-resolution measurements.

For engineers comparing metrology tools, WLI provides an ideal balance between accuracy, non-contact measurement, and automation compatibility.

The system emits white light from a low-coherence source (e.g., halogen lamp or LED), containing multiple wavelengths.

The instrument’s software compiles this data into a 3D surface map, providing quantitative information about roughness, step height, and form.

For engineers, this principle means traceable, repeatable data without mechanical contact—ideal for validating precision components and ensuring process stability.

• Non-contact operation — Eliminates stylus wear and surface damage.
• Nanometer-level vertical resolution — Detects subtle surface variations critical for performance parts.
• Fast acquisition speed — Supports batch inspection and process feedback.
• Versatility — Suitable for smooth, rough, or patterned surfaces across metals, polymers, and ceramics.
• Quantitative output — Generates ISO-compliant surface parameters (Ra, Rz, Sa, Sq).

In metrology labs, WLI systems provide the data traceability and measurement certainty engineers rely on for process validation and certification.

• Process development — Validate machining, polishing, or coating processes.
• Failure analysis — Detect wear, corrosion, or fatigue-related surface changes.
• Optical component testing — Measure lens curvature, coating thickness, and form error.
• Microelectronics — Analyze wafer flatness, MEMS structures, and thin film layers.
• Additive manufacturing — Assess surface integrity and build consistency layer by layer.

Vertical Resolution and Measurement Range

Check the system’s z-resolution (typically sub-nanometer) and its vertical scanning range. A higher range is ideal for parts with curved surfaces or significant height variation.

Objective Lenses and Field of View

Choose magnification levels that balance resolution and coverage area. Some systems allow rapid objective switching for multi-scale measurements.

Surface Type Compatibility

Consider surface reflectivity, roughness, and transparency. Systems with adaptive light intensity or specialized objectives handle a broader range of materials.

Stage and Automation Options

Motorized XYZ stages and stitching capabilities allow engineers to measure larger samples automatically or combine multiple scans into one dataset.

Software and Data Analysis

Evaluate the software’s ability to calculate surface parameters (Ra, Rq, Sa, etc.), generate ISO-compliant reports, and export data to CAD, SPC, or simulation tools.

Application Versatility

Engineers rarely measure just one type of sample, so it’s essential to choose equipment that can handle the full range of materials and geometries you encounter. Consider whether the system can reliably measure diverse surfaces—different material types, curved or cylindrical parts, steep slopes, coatings, and thin films. Can it also provide high-resolution imaging alongside measurement? And if you routinely analyze similar sample types, could automation streamline your process?

A clear understanding of your requirements helps reduce long-term costs by limiting the number of systems you need and simplifying your overall workflow.

By aligning these specifications with measurement objectives, engineers can ensure that their investment in WLI technology delivers accurate, repeatable, and actionable data for their processes.