1. A hair care device (40) that includes a light-based detector (10) for detecting hair (22) near a skin surface (21), the detector (10) comprising: a light source (11) for generating a light beam (31) with the polarization of the incident wave, - optical elements (14, 16, 17, 18) for focusing the light beam (31) on the hair (22) near the surface (21) of the skin； and - a polarization-sensitive light sensor (12, 13) for detecting light that interacts with hair (22) or skin surface (21) and has a predetermined linear polar radiation, and the light source (11) and / or optical elements (14, 16, 17, 18) are located so that the light beam (31) has several spatially separated foci (51, 52, 53) at the same time or near the hair or surface (21) skin, with different foci being arranged to coincide with the same hair, and wherein the light source (11) and / or optical elements (14, 16, 17, 18) are located so that the beam (31) light had different orientations of the incident wave polarization at multiple foci (51, 52, 53) .2. A hair care device (40) according to claim 1, wherein the light source (11) and / or optical elements (14, 16, 17, 18) are arranged so that the light beam (31) has multiple foci (51, 52) spatially separated in the lateral direction relative to the light beam (31) .3. A hair care device (40) according to claim 2, wherein the optical elements comprise a transmission grating. 4. A hair care device (40) according to claim 1, wherein the light source (11) and / or optical elements (14, 16, 17, 18) are arranged so that the light beam (31) has multiple foci (51, 53) spatially separated in the axial direction include1. Устройство (40) для ухода за волосами, которое содержит детектор (10) на основе света для обнаружения волос (22) вблизи поверхности (21) кожи, причем детектор (10) содержит:- источник (11) света для генерации светового луча (31) с поляризацией падающей волны,- оптические элементы (14, 16, 17, 18) для фокусирования светового луча (31) на волосах (
