Low_resolution_Thesis_CDD_221009_public - Visual Optics and ...

CHAPTER 2
2.1.1.1. Contact profilometry
A Detek 3000 contact profilometry system, based in CIDA, Madrid, Spain, that
provides the profile of a sample along a given direction, was used to measure flat
surfaces in Chapter 3. This apparatus uses a small probe tip that is placed on the
sample and moves across in continuous contact with the surface. The tip movement,
that outlines the surface profile, is recorded in a computer as two vectors that represent
the Cartesian coordinates of the profile. The operating range of this system is 0.2 mm
(height) x 15 mm (across). Fig. 2. 2 shows an example of a raw measurement on a flat
profile.
Fig. 2. 2. Example of a raw measurement on a flat ablated surface with the Detek
3000 contact profilometer. Custom algorithms were developed to extract the
information to a digital format.
The vertical range of that system was too low to measure the elevation differences
found in the spherical surfaces (radii 8 ~ mm). For that reason, we used a Talysurf
contact profilometry system (Taylor-Hobson, Leicester, England), based at Indra
Sistemas, Aranjuez, Madrid, Spain, for the measurement of spherical surfaces. This
system has sufficient working range to measure the profile along the 12-mm diameter
of the artificial cornea, and its resolution is higher than the roughness of the ablated
surface (typically less than 1 m). Fig. 2. 3 shows an example of raw measurement, in
which the best fitting sphere has been subtracted by the instrument’s software. This
instrument was used to test the spherical surfaces presented in Chapter 3.
Fig. 2. 3. Example of a raw measurement on a spherical ablated surface with the
Talysurf contact profilometer. The best fitting sphere has been substracted by the
instrument. Custom algorithms were developed to extract the information to a digital
format.
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