multiwavelength refractometer YV Tarakanchikova LE Dolotov AP Popov AV Bykov VV Tuchin Material and method Determination of the refractive index is based on the Fresnel equations for the reflection of light using the FTIR ID: 499363
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Slide1
Measurement of refractive index of tissues using a
multi-wavelength refractometer
Y.V.
Tarakanchikova
, L.E.
Dolotov
, A.P. Popov,
A.V.
Bykov
, V.V.
Tuchin
Slide2
Material and method
Determination of the refractive index is based on the Fresnel equations for the reflection of light using the FTIR.
Fresnel equation for reflection light polarized parallel (p) and the normal (s) to the plane of incidence of light when the angle of incidence
θi
have the form:
where
If the incident light is
unpolarized
, the reflectance of the sample is equal to:Slide3
The refractive index of biological tissue is considered complex:
ntissue = nr + i·ni where nr - the real part of the refractive index, ni - the imaginary part, which characterizes
the absorbing and scattering properties of tissue.
Material and method
-
angular
dependence of the imaginary part of the refractive index (7).Slide4
Experimental assembly
Multiwavelength Abbe refractometer ATAGO DR-M2 / 1550
Abbe
refractometer ATAGO DR-M2 / 1550.
halogen illuminator with changeable interference filters
controller of refractometerSlide5
Results
а)
b
)
c
)
The image of the field of view of the refractometer, the fixed of the camcorder.
- distilled water, measurement wavelength of 690 nm, the position of the crosshair - 1.3310;
- 40% fructose solution, measurement wavelength 690 nm, the position of the crosshairs - 1.4004;
- pork muscle tissue, measurement wavelength 930 nm, the position of the crosshair - 1.3675.
Slide6
Data Processing
transform number pixel index of refraction
n
, related with the scale of the refractometer :
n
=
n
sc
+ (
N
pix — N
cr)·K
where n-refractive index, corresponding of the pixel;
nsc - refractive index fixed to set up scale;
Npix
–pixel number of image;
Ncr
- number pixel of the image corresponding to position crosshair;
K
- calibration factor (for a wavelength of 930 nm, it equals 1.15 × 10-4).
θ
i
=
arcsin
(n/
n
p
)
where n- is refractive index,
n
p
- is refractive index of measurement prism (
n
p
= 1.6889, λ=930nm)Slide7
Data Processing
Experimental data (●) and approximation (—), using a equation (8) for muscle tissue and a 40% fructose solution.Slide8
The approximation parameters — real
nr(a)
and
imaginary
n
i
(
b
) parts
of
refractive
index, area of
partial
contact
A(
c)
muscle tissue with fructose 40%
Data ProcessingSlide9
The experimental results(•) and approximation(-) for the muscle tissue with
glucose 40%
Data ProcessingSlide10
The approximation parameters — real
nr(a)
and
imaginary
n
i
(
b
) parts
of
refractive
index, area of
partial
contact
A(
c)
muscle tissue with glucose 40%
Data ProcessingSlide11
Conclusion
Developed
method
gives
a
possibility
to
measure
the
refractive
index
of
such
turbid
medias
as
biotissue
and
its
mimicking
phantoms
at
number
of
wavelengths
.
Also
this
method
allows
to
obtain
time
resolution
of
the
diffuse
processes
under
optical
clearing
of
the
biological
tissues
.
Suggested
mathematical
model
allows
to
get
the
real
and
imaginary
parts
of
the
refractive
index
and
,
accordingly
,
the
scattering
coefficient
μ
s` of
tissues
.