A method and an optical system for evaluating the spatial distribution of the concentrations of components in tissue are disclosed. The novel detecting probe included in the optical system comprises plural optical fiber sets, each optical fiber set respectively comprises at least one source optical fiber and at least one detector optical fiber, the source optical fiber connects with the multi-wavelength light source, the source optical fiber delivers light from the multi-wavelength light source onto a tested tissue and the angle between one optical fiber set and another optical fiber set is greater than 0° and less than and not equal to 180°. Through the optical system of the present invention, the spatial distribution of the concentrations of components such as water, hemoglobin, melanin, lipid, and collagen in the tested tissue can be derived by an equation (I) defined in the present specification.
