A fluorescence imaging system, comprising: a sample platform for holding a fluorescent material; a light detector having a two dimensional array of sensing locations for detecting light emitted from the fluorescent material; a wide-field optical imaging system positioned between the sample platform and the light detector and configured to focus light emitted from field points on the sample platform onto the light detector, wherein contiguous field points on the sample platform are simultaneously imaged onto contiguous sensing locations on the light detector; an illumination system including a light source that emits excitation light in an absorption band of the fluorescent material, wherein the illumination system provides a beam of illumination that impinges on the fluorescent material at an angle relative to a detection axis, wherein a plane of incidence of the beam includes the detection axis and the scan direction; a scanning mechanism that enables continuous scanning of the beam of illumination relative to the sample platform along the scan direction; and an intelligence module coupled to the light detector and configured to determine variations along the scan direction of a height (101a,101b) of the fluorescent material parallel to the detection axis based on variations along the scan direction of positions (103a,103b) on the light detector of maximum illuminance detected by the light detector wherein the intelligence module is also operable to receive and process signals from said light detector, representing, or proportional to detected illumination, so as to generate images obtained in an imaging scan taken with the fluorescing surface at the best focus height location. a sample platform for holding a fluorescent material; a light detector having a two dimensional array of sensing locations for detecting light emitted from the fluorescent material; a wide-field optical imaging system positioned between the sample platform and the light detector and configured to focus light emitted from field points on the sample platform onto the light detector, wherein contiguous field points on the sample platform are simultaneously imaged onto contiguous sensing locations on the light detector; an illumination system including a light source that emits excitation light in an absorption band of the fluorescent material, wherein the illumination system provides a beam of illumination that impinges on the fluorescent material at an angle relative to a detection axis, wherein a plane of incidence of the beam includes the detection axis and the scan direction; a scanning mechanism that enables continuous scanning of the beam of illumination relative to the sample platform along the scan direction; and an intelligence module coupled to the light detector and configured to determine variations along the scan direction of a height (101a,101b) of the fluorescent material parallel to the detection axis based on variations along the scan direction of positions (103a,103b) on the light detector of maximum illuminance detected by the light detector wherein the intelligence module is also operable to receive and process signals from said light detector, representing, or proportional to detected illumination, so as to generate images obtained in an imaging scan taken with the fluorescing surface at the best focus height location.