Surface Finish Analysis

Roughness measurement according to ISO Standard

ISO standards require often measurement over area much larger than a single acquisition field of view. The full field of view non-scanning acquisition principle of DHM® systems combined with stitching algorithms provides quickly and robustly 3D topography of large areas, enabling to apply ISO standards.


3D representation of roughness measurement according to ISO 4288: 1996


  • Material: stainless steel roughness standard, Ra = 95 nm
  • Instrument: DHM® R-1000
  • Sample stage: motorized, for stitching.
  • Objective: 10x
  • Time scale: <4 s

Koala Software Roughness measurement software module

The integrated Koala Software roughness measurement module calculates roughness, waviness and primary profile standard surface finish parameters (Ra, Wq, Pp, etc.). It also allows the adjustment of cut-off frequencies to the specificities of your samples.


Surface roughness parameters measurements by digital holographic microscopy (DHM) | (2006) | Montfort | Publications | Spie

Surface roughness parameters measurements by digital holographic microscopy (DHM) | (2006) | Montfort | Publications | Spie


Output of result window, measured Ra is 93.64nm

Use of high NA objective for pyramidal surface roughness characterization

DHM R-1000 Measurement of the surface of a quartz wafer. A 40x objective with a NA of 0.75 is necessary to capture the light reflected by the sides of the crystal pyramid. Use of smaller NA objective does not enable to perform a measurement on the steep part of the pyramids.


  • Material: quartz wafer
  • Instrument: DHM® R-1000
  • Objective: 40x
Surface of a quartz wafer measured by DHM® with a 40x, NA=0.75 objective. FOV 160 µm x 160 µm. Rt = 1.1 micron, Ra = 105 nm.

Roughness measurement of the inner surface of a glass tube

DHM® is a non-destructive method to measure inside walls of transparent materials . This measurement examples demonstrates the measurement of the roughness of the inner surface of a glass tube with 2mm thick walls.

Measuring with an optimal optical quality

Optimal optical quality is guaranteed with DHM® by using the adapted objective. Correction of the 2mm thick glass is possible thanks to objectives available in standard optical microscopy.

Digital curvature compensation

Digital curvature compensation of the glass tube is applied thanks to the unique DHM® numerical 3D reconstruction feature.  The influence of the property of glass and of the curvature on the reflected wavefront can be corrected, improving the accuracy and the optical quality of the measurement.

Measurement can be combined with fast and automated stitching to increase measurement along the entire tube length.


  • Material: glass tube, internal diameter 2 mm
  • Instrument: DHM® R-1000
  • Objective: 20x, glass corrected 2 mm
Sketch of inner location of measured area
3D view of the tube-inside roughness