Optical profiling produces a high-precision three dimensional measurement
of the surface height of many materials. Peak to valley sensitivity
can be expressed in angstroms. Surface
peaks, valleys and slopes are accurately and repeatably measured
using NIST-traceable processes - without surface contact, a non-destructive
test.
Parameters of 3D profiles
The resulting profilometry measurement contains reliable two
dimensional cross-sections in any direction across the surface,
comparable in sensitivity and precision to stylus profilometry, but
much faster, and with greater repeatability.
A three dimensional profile makes possible precise calculation
of volume, including voids, wear, pits, grooves and failure marks,
as well as solid displacement, relative flatness, average (relative)
height variation, frequency and placement of peaks/valleys, size, step
height and shape of plateaus,
consistency or variability of a texture, the presence and shape of surface
flaws, the accuracy or precision of manufacturing, and so forth.
3D Surface Characterization
Additionally, surface
roughness and surface index can be calculated based on the cumulative
means, medians and root means of the surface variability. For structured
surfaces, 3D profiling using interferometric techniques provide an unequalled
view of results of engineered surfaces.
Applications
Researchers and scientists value the ability to measure at the same
location over time. It helps in determining the efficacy of machining,
coating, etching and chemical planarizing processes, as well as optimizing
polish, cutting
or time and materials.
Grinding, honing and polishing
3D optical profiling has been beneficially
used in determining and maintaining quality control in honing and grinding
of precision engineered surfaces.
For example, in polishing, honing
or grinding processes, successive measurements can be made of the
exact same location, to determine the cumulative effect or effectiveness
of the finishing process. Subsequent measurements are not affected by
smearing caused by stylus contact on fragile or soft surfaces. Sharp
microscopic peaks can be rounded by stylus contact, reducing their height
for subsequent measurements of the same location.
Tribology
Coatings
Metallic and polymeric composite materials for adhesive bonding. In-line
inspection.
Heat treating
Anodizing
Texture measurements
Laser texture
Laser calibration
Laser cutting
Etched surfaces
Chemical
polishing
Nanotexture fabrications development on silicates
Roughness measurements
Asperity, waviness, microwaviness and
micro-waviness.
Surface leveling. In-line
for maintaining reproducible angle of incidence.
Wear of materials
Ball bearings
Wear marks
Fatigue failure analysis
Cracks fissures
MEMS
Structure mapping
Measuring the success of fabrication and design in manufacturing microscopic
structures such as micro-electronic machine systems
(also known as MEMS), is an instrumental benefit
to the development of new design and micromachining or etching, ion
beam, or laser-cutting MEMS fabrication processes.
Measuring the efficacy of MEMS function
For example, diaphragm deflection in fluid gate microvalve development.
Using a vertical scanning interferometer, deflection of closing plates
in micro-valve arrays was measured on live, electrically charged MEMS
arrays. Deflection was seen to be essentially only 2-dimensional. The
measurements helped to prove the effectiveness of the design concept,
and measure the success of the valve in fluid control. By varying differential
pressure and obtaining a new non-contact measurement
of the deflection of the valve diaphragm at each pressure variable,
the relative shape of the diaphragm could be known at varying flow rates.
Consequently, 3D optical profilers may be useful in measurements of
deformable mirrors, electrostatic actuators, adaptive optics an MEMS
flow control. Measurements could be made at various steps in the process,
including alterations due to plasma deposition, heat-transfer phenomena
and so on. Surface micromachined MEMS, MEMS
deformable mirrors and membrane active micromirrors are also possible
candidates for successful structure
characterization. Indeed ADE Phase Shift's MicroXam is programmable
to measure micromechanical arrays automatically, or to create 3D large-area
stitched profiles of contiguous
surface material.
Measuring the response of MEMS to mechanical processes or electronic
currents — often used for working the MEMS. Measurements in
situ of activated MEMS provides live feedback of the process and
success of designs, which allows further technological development,
without damaging sensitive and fragile microstructures and micromachined
arrays as may occur when using a stylus measurement approach.
In many cases, a stylus may alter the structure of a surface, particularly
a soft or brittle surface, by rounding peaks. This can prohibit repeat
measurement of a specific location, as the subsequent measurement would
measure an altered surface structure.
