Scanning Probe Microscopy (SPM)/Atomic Force Microscopy (AFM)

DVD surface

(pictured above) 3-Dimensional Surface Profile of a Compact Disk Stamper

True 3–dimensional measurements of the surface with resolution down to the sub-Ånsgtrom level are attainable. The analysis is NON-DESTRUCTIVE with the scanning probe exerting a force on the order of nanoNewtons (10-9 N). Little or no sample preparation is required. Our instrument can easily accommodate samples 1½” x 1½” in length and 1” in thickness. The maximum scanning range is 100 microns in the x and y direction and 10 microns in the z direction.

Since the SPM measures the interaction between the scanning probe and the sample, specialty probes are available that can measure specific properties of the sample surface, such as adhesion or magnetism. We work with the customer to use the probe that best fits the characteristics of the sample surface that needs to be measured.

The Scanning Probe Microscope can be used in various modes: 

Contact Mode
The scanning probe is in contact with the sample. The topography of the sample surface is obtained by measuring the voltage change applied to the scanning piezoelectric crystals to maintain a constant deflection of the probe as it is raster scanned across the sample.

Non-Contact Mode (“Tapping” Mode)
Amplitude Mode – The scanning probe is vibrated at it’s resonance frequency. As the probe is brought near the surface, the tip-sample interaction causes a decrease in the amplitude of the resonance frequency. The topography of the sample surface is obtained by measuring the voltage change applied to the scanning piezoelectric crystals to maintain a constant amplitude of vibration as the probe is raster scanned across the sample.

Phase Mode – The scanning probe is vibrated at it’s resonance frequency and the phase shift relative to the driving signal is measured. An image of the sample surface is obtained by measuring the voltage change applied to the scanning piezoelectric crystals to maintain a constant phase shift as the probe is raster scanned across the sample. The phase shift can be used to differentiate areas on a sample with such differing properties as friction, adhesion, and viscoelasticity.

Lateral Force Mode (LFM) – At times variations in the sample are not just topographic. Chemical variations across the surface can be mapped by recording the torquing of the scanning probe. The torquing of the probe is due to changes in the tip sample interaction. Although this technique is not quantitative, it can yield very important information about the surface of the sample.

Image and Quantitative Analysis
3-dimensional surface plots and Line profiles are standard. The analysis software provides an image histogram and easily calculates line and surface roughness parameters such as Root Mean Square (RMS), Mean Deviation (Ra), and Maximum peak-to-Valley (Rt).