DiffractoStep-RV1

The DiffractoStep-RV1 is a compact, laboratory-grade instrument designed for fast and accurate thin film step height measurement using Fresnel diffraction pattern generated from an optical reflective phase step. When a light beam encounters an abrupt phase change—created by a deposited thin film on a partially masked substrate—the resulting Fresnel diffraction pattern carries direct information about step thickness. By analyzing the visibility of three central diffraction fringes and matching them to the theoretical database, the DiffractoStep-RV1 delivers reliable measurements within seconds across a wide thickness range.

This system is ideal for thin film thickness calibration, nano-coating process control, and general optical metrology, offering a cost-effective alternative to interferometry for quick thin film step height measurement.

Measurement Principle

An optical reflective phase step is generated by depositing a thin film on one side of a masked substrate. When a collimated laser beam reflects from the boundary between the coated and uncoated regions, an abrupt phase shift occurs. This leads to Fresnel diffraction step height measurement through intensity distribution of the diffraction patterns, which depends on:

• Step thickness
• Laser beam wavelength
• Angle of incidence

The DiffractoStep-RV1 analyzes the three central Fresnel fringes, extracting visibility values and comparing them to a pre-calculated database of Fresnel diffraction patterns and the corresponding measured values, covering thicknesses from 50 nm to 2 µm. This approach provides fast, repeatable, and non-contact measurements suitable for research, thin film thickness calibration, and QC environments.