Method and apparatus for imaging three-dimensional structure

An apparatus for determining surface topology of a portion of a three-dimensional structure, comprising:

• a probing member with a sensing face;
• an illumination unit for providing an array of incident light beams transmitted towards the structure along an optical path through said probing unit to generate illuminated spots on said portion;
• a light focusing optics 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 plane;
• a translation mechanism for displacing said focal plane relative to the structure 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;
• and
• 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 portion.