coatings created by other means. Of primeimportance is that deposition takes placeat room temperature. 8
Using atomic force microscopy9 (AFM),Figure 4 shows the surface micromorphol-ogy of a 2-μm-thick silicon film depositedby conventional thermal evaporation atroom temperature. The resultant film morphology exhibits a rough, poorly nucleated, nonadherent columnar porous film.
Figure 5 is an AFM evaluation of a 2-μm silicon film created at room temperature by the reactive ion plating. In thiscase, the film is fully adherent, smoothand featureless, indicative of a fully densified bulklike thin-film structure.
Protected gold alloy-replicated mirrors
Replicated mirrors produced with Darius’ alloy subsequently were coated withelemental silicon at room temperatureusing RLVIP. A film thickness of 70 nmwas employed to tune the optimal spectralperformance for the desired 1580- to
15,000-nm spectral region. A silicon film
thickness of 160 nm was used for creating
mirrors for the alternative 1300- to 1700-
nm band. The resultant measured re-
flectances demonstrate that these surface-
modified replicated mirrors are indeed
well suited to critical infrared instrumenta-
tion applications (Figures 6 and 7).
For a comparative measurement of sur-
face hardness and abrasion resistance, the
moderate abrasion methods as described in
MIL-M-13508C were re-employed. In
both of the above cases, RLVIP-protected
replicated gold alloy mirrors survived be-
yond 350 strokes without visible evidence
of any surface abrasions.
Learning from the past
Many ancient civilizations have contributed to our current modern scientificunderstanding. Countless groundbreaking
65 Photonics Spectra September 2009
Figure 5. An AFM evaluation of a 2-µm silicon film
was created at room temperature by Newport’s
patented Reactive Low Voltage Ion Plating process.
Figure 4. This AFM image shows the surface micro-
morphology of a 2-µm-thick silicon film deposited
by conventional thermal evaporation at room tem-