6 :12. Suppose that tooth dentin has an absorption coefficient of 6 cm−^1 and a
scattering coefficient of 1200 cm−^1 for a HeNe laser emitting at a wavelength
of 633 nm. Show that the optical albedo of this dental tissue is 0.995.
6 :13. Consider the cylindrical diffuser device of length L shown in Fig.6.22.
Assume the diffuser produces a uniform radial distribution along the length
of thefiber and that 80 % of the input power is radiated out of the diffuser.
If P is the optical power level input to the diffuser, what is the irradiance at a
distance R from the center of the cylinder?
6 :14. Consider a Nd:YAG laser that emits at a wavelength of 1064μm. (a) If the
absorption coefficient of an irradiated abdominal tissue isμa=18cm−^1 ,
show that the optical penetration depth into the tissue is 0.56 mm.
(b) Suppose the power from a single 16-ms Nd:YAG pulse is 2.6 W and that
it is delivered to the tissue through an opticalfiber with a core radius of 300
μm. Assuming that the factorρC≈4.2 J/(cm^3 /°C) holds for tissue, show that
the maximum temperature rise in the tissue due to this pulse is 63 °C.
6 :15. Compare the radiant exposure in J/cm^2 for the following two optical pulses:
(a) A 10-ps pulse with an irradiance of 8× 1011 W/cm^2
(b) A 100-ns pulse with an irradiance of 7.3× 109 W/cm^2
(Answer: 8 J/cm^2 and 730 J/cm^2 .)References
- W.F. Cheong, S.A. Prahl, A.J. Welch, A review of the optical properties of biological tissues.
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- A.J. Welch, M.J.C. van Gemert (eds.),Optical-Thermal Response of Laser-Irradiated Tissue,
2nd edn. (Springer, Berlin, 2011) - M. Schmitt, T. Mayerhöfer, J. Popp, Light-matter interaction, Chap. 3, inHandbook of
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Heinemann (Wiley, London, 2011) - S.L. Jacques, Optical properties of biological tissues: a review. Phys. Med. Biol. 58 (11), R37–
R61 (2013) - K. Kulikov,Laser Interaction with Biological Material(Springer, Berlin, 2014)
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Photonics Handbook, 2nd edn., ed. by T. Vo-Dinh (CRC Press, Boca Raton, FL, 2014),
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Singapore, 2016) - A.H.-P. Ho, D. Kim, M.G. Somekh (eds.), Handbook of Photonics for Biomedical
Engineering(Springer, Berlin, 2016)
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