<s>
Optic	B-Device
crystals	I-Device
are	O
crystals	O
that	O
can	O
be	O
used	O
to	O
direct	O
a	O
beam	O
of	O
light	O
.	O
</s>
<s>
Optic	B-Device
crystals	I-Device
can	O
work	O
as	O
directional	O
guides	O
to	O
the	O
light	O
in	O
photonic	O
devices	O
.	O
</s>
<s>
Opticmechanics	O
deals	O
with	O
the	O
grinding	O
,	O
polishing	O
and	O
refining	O
of	O
optic	B-Device
crystals	I-Device
.	O
</s>
