In a laser scanning method for measuring in vivo substances, wavelength of the anti-Stokes line is made greater than wavelength absorption band of the specific substance, the wavelength of the probe light is shifted from the wavelength of the anti-Stokes line by a shift amount of Raman scattering of the specific substance, and the wavelength of the Stokes light is shifted from the wavelength of the probe light by the shift amount of the Raman scattering of the specific substance. According to this, density (concentration and distribution) of lutein in an eye fundus is measured quantitatively and non-invasively from a signal strength level of the anti-Stokes line.1
