study of birefringence alterations during optical clearing ... · cross-polarized state...

Study of birefringence alterations during

optical clearing of biological tissues

Mariia Borovkova

Doctoral student at the I4Future programme

Oulu, 2017

Optoelectronics UnitFaculty of Information Technology and Electrical Engineering

University of Oulu

Supervisors: Dr. Alexey Popov, Prof. Igor Meglinski, Dr. Alexander Bykov

University of Oulu6/5/20172

Outline

Polarization sensing intro:

Applications

The Stokes Parameters, Poincare Sphere

‒ Birefringence

‒ Skin properties and Optical Clearing

‒ Polarization-sensitive optical biopsy - experiments

‒ Results and analysis

‒ Next steps

https://en.wikipedia.org/wiki/Polarization_(waves)


Polarization: applications

3D movies

Different types of polarization captured by 2 eyes

Polarized sunglasses reduce glare

Polarized lenses for photography

http://blog.pugsgear.com/What-Exactly-Do-Affordable-Polarized-Sunglasses-Do

https://www.sunglasswarehouse.com/blog/sunglasses-tints/


Polarization: applications

The phenomenon of stress induced birefringence allows

for stresses in transparent materials to be readily observed

https://en.wikipedia.org/wiki/Photoelasticity

https://fi.pinterest.com/pin/320248223475892257/

Photoelasticity


Polarization: applications in medicine

Top: the polarization image

has removed the melanin

of the freckle.

Bottom: the polarization

image reveals the

structure of a benign

pigmented nevus.

Jacques, S. L., Roman, J. R., & Lee, K. (2000). Imaging superficial tissues with

polarized light. Lasers in surgery and medicine, 26(2), 119-129.

Polarized Light Camera

Normal white light and polarization

images of freckle and benign nevus.


sourse

polarizer

polarizer

lens

lens

screen

photodetector

object image in

polarized light

polarizer

polarizer

object

Two polarization filters are crossed – no light can get

through to the detector

Two polarization filters are still crossed but due to

birefringent properties of the object light gets thought

Only light from the sample gets

throught

Invisible becomes visible

No sample

https://www.youtube.com/watch?v=W6v7JdK4sps

sensor

polarizer

polarizer

sensor

Polarization Microscopy


The Stokes Parameters

https://en.wikipedia.org/

LHP light

0

0

1

1

I0

LVP light +45º light -45º light

0

0

1

1

I0

0

1

0

1

I0

0

1

0

1

I0

RCP light

1

0

0

1

I0

LCP light

1

0

0

1

I0

Examples:

I = the total irradiance

Q = the excess in intensity of light transmitted by a horizontal polarizerover light transmitted by a vertical polarizer

U = the excess in intensity of light transmitted by a 45° polarizerover light transmitted by a 135° polarizer

V = the excess in intensity of light transmitted by a RCP filter over lighttransmitted by a LCP filter

Degree of polarization = 𝑄2 +𝑈2 +𝑉2

𝐼= 1 for polarized light,

0 for unpolarized light


Poincare Sphere representation

Jules Henri Poincaré

(1854–1912).

Right-hand circular

LinearDiagonal

Left-hand circular

LinearAnti-diagonal

LinearVertical

LinearHorizontal Sphere surface –

fully polarized light(DOP = 100 %)

https://en.wikipedia.org/

Shurcliff, William A. "Polarized light. Production

and use." Cambridge, Mass.: Harvard University

Press,| c1966 1 (1966).

QU

V


Outline

‒ Polarization sensing intro:

Applications


Birefringence

‒ Optical Clearing and Skin properties



‒ Next stepshttps://en.wikipedia.org/wiki/Polarization_(waves)


Polarization and refraction

Curcular polarization

Curcular polarization with a shifted phase

Linear polarization

Linear polarization with a shifted phase

Isotropic medium

Simulated using EMANIM – free application for visualizing electromagnetic waveshttp://cddemo.szialab.org/

http://cddemo.szialab.org/


Birefringence - double refraction

Refraction index for HP = 1.05 Refraction index for LP = 1

Circular polarization

transfers into linear

and then to circular

of other helicity

Anisotropic medium

Simulated using EMANIM – free application for

visualizing electromagnetic waveshttp://cddemo.szialab.org/

http://cddemo.szialab.org/


Outline

- Polarization sensing intro:

Applications


‒ Birefringence

Skin properties and Optical Clearing



‒ Next steps

http://millbasindoctor.com/skinconditions/


Skin structure and properties

Dermis consists of: collagen fibers, elastic fibers, reticular fiber and extrafibrillar matrix.

Thickness of dermis (human skin) is 1–5 mm, about 30 times that of epidermis.

Dermis is the major barrier for delivering light deeper into skin

Feng, X., Patel, R., & Yaroslavsky, A. N. (2015). Wavelength optimized cross‐polarized wide‐field imaging for noninvasive and rapid evaluation of dermal structures. Journal of biophotonics, 8(4), 324-331.

Cross-polarized 440 nm image of collagen fibers

The refractive indices mismatch between fibers and matrix produces high scattering of dermis.

http://bayareapelleve.com/pelleve/collagen/


Optical Clearing

http://www.hematology.org/Thehematologist/Diffusion/5124.aspx

Optical clearing is used for reduction of scattering of biological tissues with a primary aim to increase penetration depth and contrast of optical imaging techniques.

Hama, H., Kurokawa, H., Kawano, H., Ando, R., Shimogori, T., Noda, H., ... &

Miyawaki, A. (2011). Scale: a chemical approach for fluorescence imaging and reconstruction of transparent mouse brain. Nature neuroscience, 14(11), 1481-1488.

Optical clearing method is based on the concept of matching of refractive indices of scatterers and ground material or on changing of the packing parameters of the tissue and/or size of the scatterers.


• Skin: higly scattering, birefringent material.

• Birefringence in skin: linear anisotropy of fibrous structures. The refractive index of a medium is higher along the length of a fiber than along the cross section.

• Tissue structure: a system composed of parallel cylinders that create an uniaxial birefringent medium with the optic axis parallel to the cylinder axes. This is called birefringence of form.

• Form birefringence arises when the relative optical phase between the orthogonal polarization components is nonzero for forwardly scattered light.

• Phase retardation, δ, between orthogonal polarization components, is proportional to the distance (d) traveled through the birefringent medium.

• The effect of tissue birefringence on the propagation of linearly polarized light is dependent on the angle between the incident polarization orientation and the tissue axis.

Skin birefringence properties

Tuchin, V. V., Wang, L., & Zimnyakov, D. A. (2006). Optical polarization in

biomedical applications. Springer Science & Business Media.


Outline


Applications


‒ Birefringence


Polarization-sensitive optical biopsy - experiments


‒ Next steps


Polarization-sensitive optical biopsy

Meglinski, I. (2014, November). Polarized Light Biosensing. In Asia Communications and Photonics Conference (pp. ATh2G-2). Optical Society of America.

University of Oulu

Experiment features

Illumination color – red

Incident polarization state: Right-handed Circular Polarization

6/5/2017 Replace footertext if needed18

Forward scattering of circularly

polarized light => initial helicity

Reflection (or backscattering) of

circular polarization => helicity flip

Circularly polarized light:

“sense of direction”

“polarization memory”

the largest penetration depth

Photons in the tissue undergo a number of

scattering events:

Sridhar, S., & Da Silva, A. (2016). Enhanced contrast and depth resolution in polarization imaging using

elliptically polarized light. Journal of biomedical optics, 21(7), 071107-071107.

University of Oulu6/5/2017 Replace footertext if needed19

Distance between source and detector

Experiment features

Increase of penetration depth

Signal is not saturated by light in the cross-polarized state (helicity-flipped)

Contribution of co-polarized component grows with the increase of the distance

Kunnen, B., Macdonald, C., Doronin, A., Jacques, S., Eccles, M., & Meglinski, I. (2015). Application of circularly polarized light for

non‐invasive diagnosis of cancerous tissues and turbid tissue‐like scattering media. Journal of biophotonics, 8(4), 317-323.

Chicken skin(turned

inside out)

Glycerol

Translationstage

640 nm laser,quater-wave

plate

objective

Stokesvector

polarimeter

1st sample1st day

2nd sample3rd day

• Experiment duration: 3 hours• 1D scanning(1-cm line, step 100 µm)• 100 points in the sample


Outline


Applications


‒ Birefringence



Results and analysis

‒ Next steps


Raw data for Sample 1

Color map represents time flow on the Poincare sphere

Degree of PolarizationPower

Stokes VStokes UStokes Q

Space

Time

Incident light polarization


Raw data for Sample 2

Color map represents time flow on the Poincare sphere

Space

TimeDegree of PolarizationPower

Stokes VStokes UStokes Q


Typical results

0 20 40 60 80 100 120 140 160 180

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

Stokes Q

Stokes U

Stokes V

3 Stokes Parameters

time (min)0 20 40 60 80 100 120 140 160 180

5

10

15

20

25

30

35

40

45Degree of Polarization

time (min)

0 20 40 60 80 100 120 140 160 1800

20

40

60

80

time (min)

Phase (deg)


Results analysis

• During the process of optical clearing, the V Stokes component showsthe most noticeable down trend due to scattering reduction andbirefringence alterations in the chicken skin sample during theoptical clearing

• The described polarization-based modality allows for fundamentalstudy of properties of biological tissues.

• It is possible to assess freshness of meat using polarization-sensitiveoptical biopsy (should do more experiments to prove it)

25


Outline


Applications


‒ Birefringence


‒ Polarization-sensitive optical biopsy – experiments


Next steps


Next step: tissue under strain


Future plans

• Same experiments in transmission mode

• Experiments including rotation of the sample

• More experiments to investigate the possibility of using this modalityfor noninvasive meat freshness monitoring

• Experiments with cancerous tissues (polarization-sensitive optical boipsy)

Thank you!

Mariia Borovkova

[email protected]

Summer School on Optics & Photonics

June 1-3, 2017, Oulu, Finland

mailto:[email protected]


Optical Clearing

Before the experiment Right after the experiment

Before the experimentNext day after the experiment

University of Oulu

Non-invasive diagnosis of cancerous tissues

6/5/2017 Replace footertext if needed31

Kunnen, B., Macdonald, C., Doronin, A., Jacques, S., Eccles, M., & Meglinski, I. (2015). Application of circularly polarized light for

non‐invasive diagnosis of cancerous tissues and turbid tissue‐like scattering media. Journal of biophotonics, 8(4), 317-323.

Ellipticity is much higher

for the cancerous tissue

Increased average size of

tumorous lung cell nuclei

higher anisotropy of

scattering, increase in

forward scattering

co-polarized helicity has a

stronger influence

study of birefringence alterations during optical clearing ... · cross-polarized state...

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