The present invention relates to an optical device for imaging and measuring characteristics of object: surface shape, surface spectral reflectance and structure of sub-surface layers. In particular, the invention relates to imaging of topography of human skin and skin sub-surface layers and determination of concentration of skin constituents. The present invention has applications in areas such as skin care, dermatology, cosmetics, wound management and tricology. The imaging device of the invention significantly improves photometric stereo measurements by suppressing specular reflection and allows accurate determination of the surface shape. Consequently it allows elimination of the influence of the shape and illumination conditions on spectral measurements and allows accurate measurement of skin constituents.
