Large samples that have complex geometric properties can be difficult to work with due to sample preparation, sharp angles, curvature and size.
In this study, the Nanovea HS2000 Line Sensor will be used to scan an oyster shell and so demonstrate its capability when scanning a large, biological sample with complex geometry. Although this study uses a biological sample, the same concepts are applicable to other samples.
Importance of 3D Non-Contact Profilometry on an Oyster Shell
The Nanovea HS2000 Line Sensor will display its ability to work with large samples with unique geometries by scanning the entire surface of an oyster shell. Samples typically need to be securely mounted to the stage in order to mitigate their displacement as the stage moves.
Usually, this requires additional sample preparation or a fixture to be used. However here, little to no sample preparation is needed due to the smooth air bearing stages on the Nanovea HS2000. This study demonstrates a technique known as patching, which allows the Nanovea HS2000 Line Sensor to capture a surface that has features taller than the instruments lateral range or the optical sensors height range.
This is achieved by taking numerous scans at various heights and then overlaying them at their relative offsets. Using the stages’ 3 axis motion control, specified steps can be indexed in the z direction to speed up the process.
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An oyster shell was scanned using the Nanovea HS2000L Line Sensor. In order to represent the whole shell, multiple scans were conducted at various heights and reconstructed via patching.
Table 1: The following test parameters were used for each of the 9 scans performed for this study.
||400 p ps
||140 mm x 90 mm
||25 µm x 25 µm
|Measurement Time (h:m:s)
Sample of Oyster Shell Tested
Results: Series of Surfaces
In order to obtain height data over the whole surface, a total of nine scans were conducted on the oyster shell.
Results: 3D Surface
The patched 2D and 3D surface is shown below. Using the Nanovea HS2000L Line Sensor, the whole surface of the oyster shell was obtained, without compromising on the resolution. The 3D view shows small features on the surface of the shell.
Results: Surface Roughness Analysis
By applying a gaussian filter of 1.5 mm, the surface roughness of the oyster shell was obtained. This is shown below. This excludes form (or waviness) that is larger than the cut-off index, and leaves behind features that represent the roughness of the oyster shell. Stage noise was not observed in the surface roughness analysis, despite the lack of a fixture.
In order to recreate the surface of the oyster shell using the Nanovea HS2000 Line Sensor, a total of nine scans were used. The patched surface was used to measure the roughness of the oyster shell by removing the form (or waviness) of the sample. Patching can also be used to measure much finer roughnesses on a large sample that would normally be beyond the height range of the optical sensor.
For example, large conical lenses need a very fine step size in order to quantify any microscopic features than can be present. The Nanovea HS2000 Line Sensor can conduct profilometry measurements on large samples with abnormal geometries, whilst retaining high resolution and requiring minimal sample preparation.
This information has been sourced, reviewed and adapted from materials provided by Nanovea.
For more information on this source, please visit Nanovea.