The surface roughness and precise dimensions of dental screws can be vital to their proper functionality. Many dimensions could be required such as angles, step heights, distances and radii. For any medical device being used inside the body surface roughness is also an important consideration.
Importance of 3D Non-Contact Profilometer for Dimensional Study
The 3D Non-Contact Profilometer can measure nearly any surface using axial chromatism which is unlike other techniques such as touch probes or interferometry. Furthermore, samples sizes can vary widely because of open staging and no sample preparation is needed. During surface profile measurement nano through to macro range is obtained with zero influence from sample absorption or reflectivity. It also has advances ability to measure high surface angels and no software manipulation of results is necessary. It is easy to measure any material: opaque, polished, specular, rough, diffuse, transparent etc. The Non-Contact Profilometer provides an ideal, broad and user friendly capability to maximize surface studies when volume lost measurements are required. It also has the benefits of combined 2D and 3D capability.
The Nanovea ST400 Profilometer is used in this application to measure a flat surface along with screw features in a single measurement on a dental screw. The flat area is used to calculate surface roughness and various dimensions of the thread features will be determined.
The False Colour View and 3D View shows a flat area with threading starting on either side. This provides users with a straightforward tool to enable them to directly observe the morphology of the screw from different angles. In order to measure the surface roughness, the flat area was extracted from the full scan.
2D Surface Analysis
Line profiles can be extracted from the surface which gives a crossectional view of the screw. Step height and Contour Analysis studies were used to measure precise dimensions at a certain location on the screw.
This application has demonstrated how the Nanovea 3D Non-Contact Profilometer can precisely calculate the local surface roughness along with larger dimensions in a single measurement. A local surface roughness of 0.9637 mm is shown by the data.
The threads have an average height of 0.413 mm and the radius of the screw between threads was 1.729 mm. The average angle between the threads was 61.3°. Only a portion of the calculations available in the analysis software are shown in the data.
The Chromatic Confocal technique uses a white light source, where the light passes through an objective lens with a high degree of chromatic aberration. The refractive index of the object lens varies in relation to the light’s wavelength.
Effectively, each separate wavelength of the incident white light will re-focus at a different distance from the lens (different height). A single monochromatic point will be focalized to form the image when the measured sample is within the range of possible heights.
Only the focused wavelength will pass through the spatial filter with high efficiency because of the confocal configuration of the system and this causes all other wavelengths to be out of focus.
Diffraction grating is used for the spectral analysis. In this technique, each wavelength is deviated at a different position, intercepting a line of CCD. This in turn indicates the position of the maximum intensity and allows direct correspondence to the Z height position.
Chromatic Confocal technology measures height directly from the detection of the wavelength that hits the surface of the sample in focus. This is a direct measurement with no mathematical software manipulation causing errors as in probe contact or the manipulation Interferometry technique.
This provides unmatched accuracy on the surface measured since a data point is either measured accurately and without software interpretation, or not at all. The software completes the unmeasured point but the user is fully aware of this and can be confident that there are no hidden artifacts due to software guessing.
Nanovea optical pens have zero influence from absorption or sample reflectivity. Variations need no sample preparation and have an advanced ability to measure high surface angles. Capable of large Z measurement ranges. Measure any material: transparent or opaque, specular or diffusive, polished or rough. Measurement includes: Profile Dimension, Roughness, Shape Form Topography, Finish Texture, Volume Area, Flatness Warpage Planarity, Step-Height Depth Thickness and many others.
This information has been sourced, reviewed and adapted from materials provided by Nanovea.
For more information on this source, please visit Nanovea.