2010 TRI/PRINCETON CONFERENCE 99 Figure 20. Example of two in vivo measurements on human heads for two different shades of hair. The same applications presented before can be applied to in vivo measurements thanks to its fast acquisition time. No blur has been observed in the image. CONCLUSION We have presented a new method to measure the angle of orientation of hair fi ber, based on polarization analysis and imaging. Contrary to current methods that use conventional imaging followed by image processing, our technique delivers the measurement of the

JOURNAL OF COSMETIC SCIENCE 100 orientation of the birefringence axis of the hair fi ber, for each pixel of the image. The measurement operates on single fi ber, hair trees, and full head, for laboratory and in-vivo applications. Thanks to near-infrared illumination, every type of hair can be analyzed, from blond to dark, straight to curly. Application for shampoo/conditioner evaluation is demonstrated. In-vivo measurement on real model can also be done as the image acquisi- tion is fast enough as it takes about one second. This technique permits to study precisely the infl uence of the orientation of hair fi ber on the visual appearance. It opens numerous potential applications for product development, product evaluation and claim substan- tiation. This new sensor opens the door to the defi nition of new measurement procedures and new parameters in order to fully quantify the visual appearance of hair. This tech- nique has been patented (Patent pending: application US12/567,579). REFERENCES (1) S. Hariharan, S. A. Sathyakumar, and P. Ganesan, Measuring of fi bre orientation in nonwovens using image processing, www.fi bretofashion.com (2) Y. J. Han, Y. J. Cho, W. E. Lambert, and C. K., Identifi cation and measurement of convolutions in cot- ton fi ber using image analysis, Artifi cial Intelligence Review, 12(1–3), 201–211 (1998). (3) K. E. Duckett and C. C. Cheng, The detection of cotton fi ber convolutions by the refl ection of light, Textile Res. J. 42, 263–268 (1972). (4) R. K. Curtis and D. R. Tyson, Birefringence: Polarization microscopy as a quantitative technique of human hair analysis, J. Soc. Cosmet. Chem., 27, 411–431 (1976). (5) A. C. Brown, R. B. Belser, R. G. Crounse, and R. F. Wehr, A congenital hair defect: Trichoschisis with alternating birefringence and low sulfur content, J. Invest. Dermatol., 54, 496–509 (1970). (6) Tjitske van Kampen, Optical properties of hair, Masters project, January 1, 1997.