Optical Coatings

Fundamental Optics
Material Properties Optical Specifications Gaussian Beam Optics
Optical Coatings
INTRINSIC STRESS
Even in the absence of thermal-contraction-induced stress, the
layers often are not mechanically stable because of intrinsic stress
from interatomic forces. The homogeneous thin film is not the
preferred phase for most coating materials. In the lowest energy,
natural form of the material, molecules are aligned in a crystalline
symmetric fashion. This is the form in which intermolecular forces
are more nearly in equilibrium.
In addition to intrinsic molecular forces, intrinsic stress results
from poor packing. If packing density is considerably less than
100%, the intermolecular binding may be sufficiently weakened to
make the layer totally unstable.
PRODUCTION CONTROL
Two major factors are involved in producing a coating to perform
to a particular set of specifications. First, sound design techniques
must be used. If design procedures cannot accurately predict the
behavior of a coating, there is little chance that satisfactory coatings
will be produced. Second, if the manufacturing phase is not carefully
controlled, the thin-film coatings produced may perform quite
differently from the computer simulation.
Melles Griot uses the latest computer design programs with
exhaustive iterations to ensure that the final design is optimized.
Manufacturing high-quality thin films is not trivial. At Melles Griot,
more effort is expended on monitoring thin-film manufacture than
on any other single manufacturing procedure. Without such careful
monitoring, the tedious design and optimization phase would
be wasted.
Great care is taken in coating production at every level. Not only
are all obvious precautions taken, such as thorough precleaning and
controlled cool down, but even the smallest details of the manufacturing
process are carefully controlled. Our thoroughness and
attention to detail ensures that the customer will always be supplied
with the best design, manufactured to the highest standards.
QUALITY CONTROL
All batches of Melles Griot coatings are rigorously and thoroughly
tested for quality. Even with the most careful production control,
this is necessary to ensure that only the highest quality parts are
shipped.
Our inspection system meets the stringent demands of
MIL-I-45208A and our spectrophotometers are calibrated to
standards traceable to the National Institute of Standards and
Technology (NIST). Upon request, we can provide complete
environmental and photometric testing to MIL-C-675 and
MIL-M-13508. All are firm assurances of dependability and
accuracy.
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