An apparatus for determining surface topology of a teeth portion, comprising: a probing member with a sensing face; an illumination unit (28, 32, 34, 38) for providing an array of incident light beams transmitted towards the teeth portion along an optical path through said probing member to generate illuminated spots on said teeth portion; a light focusing optics (42, 44) defining one or more focal planes forward said probing face at a position changeable by said optics, each light beam having its focus on one of said one or more focal planes; a translation mechanism (70, 72) coupled to said focusing optics for displacing said focal plane relative to the teeth portion along an axis defined by the propagation of the incident light beams; a detector having an array of sensing elements for measuring intensity of each of a plurality of light beams returning from said spots propagating through an optical path opposite to that of the incident light beams; a processor coupled to said detector for determining for each light beam a spot-specific position, being the position of the respective focal plane of said one or more focal planes yielding maximum measured intensity of the returned light beam, and based on the determined spot-specific positions, generating data representative of the topology of said teeth portion, wherein the probing member, the illumination unit (28,32,34,38), the focusing optics (42,44) and the translation mechanism (70,72) are included together in a hand-held device, wherein said incident light beams are polarized, the apparatus comprising a polarization filter for filtering out, from the returned light beams, light components having the polarization of the incident light beams, whereby light which is detected is that which has an opposite polarization to that of the incident light. a probing member with a sensing face; an illumination unit (28, 32, 34, 38) for providing an array of incident light beams transmitted towards the teeth portion along an optical path through said probing member to generate illuminated spots on said teeth portion; a light focusing optics (42, 44) defining one or more focal planes forward said probing face at a position changeable by said optics, each light beam having its focus on one of said one or more focal planes; a translation mechanism (70, 72) coupled to said focusing optics for displacing said focal plane relative to the teeth portion along an axis defined by the propagation of the incident light beams; a detector having an array of sensing elements for measuring intensity of each of a plurality of light beams returning from said spots propagating through an optical path opposite to that of the incident light beams; a processor coupled to said detector for determining for each light beam a spot-specific position, being the position of the respective focal plane of said one or more focal planes yielding maximum measured intensity of the returned light beam, and based on the determined spot-specific positions, generating data representative of the topology of said teeth portion, wherein the probing member, the illumination unit (28,32,34,38), the focusing optics (42,44) and the translation mechanism (70,72) are included together in a hand-held device, wherein said incident light beams are polarized, the apparatus comprising a polarization filter for filtering out, from the returned light beams, light components having the polarization of the incident light beams, whereby light which is detected is that which has an opposite polarization to that of the incident light.