In many industries, thin films play a critical role — from protective coatings and optical films to electronic components. One key parameter that affects performance is film thickness. However, accurately measuring thin film thickness can be challenging due to the complex nature of its surface and internal structure.
What Makes Thin Film Thickness Hard to Measure?
Thin films are rarely perfectly smooth. Their surfaces can include:
Tiny pinholes
Micro-cracks
Fibers, impurities, or lattice defects
Adsorbed molecules on the surface
This makes the thickness non-uniform, and depending on how you define “thickness”, you may refer to:
Shape thickness – geometric distance from base to surface
Mass thickness – based on weight and density
Physical thickness – based on optical or material properties
Traditional vs. Optical Methods
There are two main ways to measure film thickness:
Direct methods – physically measuring with tools like micrometers or using contact-based instruments
Indirect methods – using optical or electronic techniques
As industries move toward non-contact and high-precision inspection, optical methods are becoming more popular.
Why Use a Chromatic Confocal Sensor?
Chromatic confocal sensors (like those from Hypersen) offer an optical, non-contact solution to measure thin film thickness.
Here’s how it works:
A broadband white light is projected onto the film.
The light passes through the transparent film and reflects from both the top surface and the substrate.
The sensor captures the reflected signal and calculates the distance between the two surfaces.
The result? A highly accurate thickness measurement — without touching the material.
Key Benefits:
Works even on irregular or curved surfaces
No damage to sensitive films
Micron-level accuracy
Real-time measurement for inline inspection
Typical Applications
Optical coatings (e.g., AR/IR filters)
Transparent adhesives
Protective films on displays
Semiconductor processes
