<s>
Micro-spatially	B-Algorithm
offset	I-Algorithm
Raman	I-Algorithm
spectroscopy	I-Algorithm
(	O
micro-SORS	O
)	O
is	O
an	O
analytical	O
technique	O
developed	O
in	O
2014	O
that	O
combines	O
SORS	B-Algorithm
with	O
microscopy	O
.	O
</s>
<s>
The	O
technique	O
derives	O
its	O
sublayer‐resolving	O
properties	O
from	O
its	O
parent	O
technique	O
SORS	B-Algorithm
.	O
</s>
<s>
The	O
main	O
difference	O
between	O
SORS	B-Algorithm
and	O
micro-SORS	O
is	O
the	O
spatial	O
resolution	O
:	O
while	O
SORS	B-Algorithm
is	O
suited	O
to	O
the	O
analysis	O
of	O
millimetric	O
layers	O
,	O
micro-SORS	O
is	O
able	O
to	O
resolve	O
thin	O
,	O
micrometric-scale	O
layers	O
.	O
</s>
<s>
Similarly	O
to	O
SORS	B-Algorithm
technique	O
,	O
micro-SORS	O
is	O
able	O
to	O
preferentially	O
collect	O
the	O
Raman	O
photons	O
generated	O
under	O
the	O
surface	O
in	O
turbid	O
(	O
diffusely	O
scattering	O
)	O
media	O
.	O
</s>
<s>
Micro-SORS	O
is	O
particularly	O
useful	O
when	O
dealing	O
with	O
precious	O
or	O
unique	O
objects	O
as	O
for	O
Cultural	O
Heritage	O
field	O
and	O
Forensic	O
Science	O
or	O
in	O
biomedical	O
applications	O
,	O
where	O
a	O
non-destructive	O
molecular	O
characterization	O
constitute	O
a	O
great	O
advantage	O
.	O
</s>
<s>
To	O
date	O
,	O
micro-SORS	O
has	O
been	O
mainly	O
used	O
to	O
characterize	O
biological	O
materials	O
such	O
as	O
bones	O
,	O
blood	O
,	O
and	O
Cultural	O
Heritage	O
materials	O
,	O
especially	O
paint	O
stratigraphies	O
.	O
</s>
<s>
Micro-SORS	O
was	O
developed	O
on	O
a	O
conventional	O
micro-Raman	O
instrument	O
,	O
and	O
portable	O
micro-SORS	O
prototypes	O
are	O
currently	O
under	O
further	O
optimization	O
to	O
enable	O
in-situ	O
measurements	O
and	O
avoid	O
the	O
need	O
of	O
sampling	O
.	O
</s>
<s>
Micro-SORS	O
permits	O
to	O
preferentially	O
collect	O
these	O
displaced	O
photons	O
coming	O
from	O
the	O
sub-surface	O
by	O
enlarging	O
(	O
defocusing	O
)	O
or	O
separating	O
laser	O
excitation	O
and	O
collection	O
zones	O
(	O
Full	O
micro-SORS	O
)	O
.	O
</s>
<s>
This	O
more	O
sophisticated	O
micro-SORS	O
variant	O
provides	O
a	O
complete	O
separation	O
of	O
laser	O
excitation	O
and	O
collection	O
zones	O
( Δx	O
offset	O
)	O
that	O
requires	O
a	O
hardware	O
or	O
a	O
software	O
modification	O
to	O
a	O
conventional	O
Raman	O
microscope	O
.	O
</s>
<s>
The	O
separation	O
can	O
be	O
achieved	O
by	O
using	O
an	O
external	O
probe	O
or	O
fibre	O
optics	O
to	O
deliver	O
the	O
laser	O
,	O
by	O
displacing	O
the	O
laser	O
spot	O
by	O
moving	O
the	O
beam-steer	O
alignment	O
mirrors	O
,	O
by	O
using	O
a	O
spatially	O
resolved	O
CCD	B-Algorithm
,	O
by	O
using	O
a	O
digital	O
micro-mirror	O
device	O
(	O
DMD	O
)	O
,	O
by	O
moving	O
the	O
tip	O
of	O
the	O
Raman	O
detection	O
fibre	O
to	O
perform	O
an	O
off-confocal	O
detection	O
of	O
the	O
signal	O
or	O
by	O
combining	O
hyperspectral	O
SORS	B-Algorithm
and	O
defocusing	O
micro-SORS	O
.	O
</s>
<s>
To	O
reconstruct	O
the	O
micro-layer	O
succession	O
it	O
is	O
required	O
to	O
collect	O
a	O
conventional	O
Raman	B-Algorithm
spectrum	I-Algorithm
and	O
at	O
least	O
a	O
one	O
micro-SORS	O
spectrum	O
;	O
the	O
acquisition	O
of	O
several	O
spectra	O
at	O
gradually	O
increasing	O
defocusing	O
distances	O
or	O
spatial	O
offsets	O
is	O
usually	O
the	O
best	O
way	O
to	O
approach	O
unknown	O
materials	O
.	O
</s>
<s>
Micro-SORS	O
was	O
developed	O
to	O
address	O
the	O
need	O
of	O
a	O
non-destructive	O
analytical	O
technique	O
with	O
high	O
chemical	O
specificity	O
for	O
the	O
non-destructive	O
analysis	O
of	O
thin	O
painted	O
layers	O
.	O
</s>
