DEVICE TO MEASURE HAIR LUSTER 239 specular reflection incident light diffuse reflection vehicle colorant / Figure 1. Reflection process of heterogeneous material. flows, were examined. The schematic representation of an optical system is shown in Figure 3. The reflectance of human hair was measured under the condition of the incident angle 0 at 45 degrees, with the receiving angle qb changing from -20 degrees to 70 degrees and arrangement angles p of 0 degrees, 45 degrees, 90 degrees, and 180 degrees. EXAMINATION OF THE OPTICAL SYSTEMS In the actual measurement using DRM, it is necessary to measure both the surface brightness It, including diffuse and specular compositions, and the diffuse composition Ia'. If the measurement angle of Ir is set to 45 degrees, there is the possibility of light source receiver hair Figure 2. Structure of the experimental device.

24O joURNAL OF cosMETIC scIENCE light source receNer I (root) ' hair (tip) Figure 5. Structure of the experimental device for changing the angle of hair. 4. One is a systena that has angle 0 of)5 ...... Figure obtaining two kinds of optical systenaS, as shown in degrees.twosourcesreceivingthesereceia•oflightandandL,•owhich is a y one light source and two receivers, with an incident • ,stem rhar has 0 degrees and 45 angles 4 ) of 0 degrees and 45 degrees. The other degrees exanained to and one receiver, with incident angles 0 of derernaine angle 4 ) of 45 degrees. These systems were sysrenaS showed more accuracy. DE¾ICE coMPAtklsoN OF MEASUREMEwe20oerAssageasseinEXPEexperranginBYbyfemales55EYALUAevatuatiomales,sENSORY(29sensoryANDandsubiectsdevicenewjapanese AN Measurements by the an conapare& Eighty-four •_/•ceNer light source receNe light source • receNer light source ß • • hair hair (b) 2 lights, 1 receive (a) 1 light, 2 receivers Figure 4. Optical systems for the measuring device.