An improved method and apparatus for diffuse reflectance spectroscopy. A specular control device is provided that can discriminate between diffusely reflected light that is reflected from selected depths or layers within the tissue. The specular control device permits a spectroscopic analyzer to receive the diffusely reflected light that is reflected from, for example, a first layer or depth within the tissue, while preventing the remaining diffusely reflected light from reaching the spectroscopic analyzer. Furthermore, the specular control device may prevent the specularly reflected light (e.g. surface reflected light) from reaching the spectroscopic analyzer.