Fluorescence imaging system compatible with macro and micro scanning

Abstract

A coaxial illumination and collection laser scanning system provides substantially uniform detection sensitivity across the field of view of an objective lens by reducing lateral chromatic aberrations at the expense of amplifying axial chromatic aberrations. Axial chromatic aberrations in the system are removed in the path of a retro-beam. A laser is in optical communication with the objective lens. The laser produces a collimated beam of coherent light that is directed by a scanner through the objective lens to illuminate a raster of spots on the sample's surface, thereby stimulating a series of small regions of the sample to emit light. The system may be used as a confocal or non-confocal imaging system. Alternatively, the system may be employed for reflection imaging of the laser beam. In a second embodiment, a plurality of lasers are provided, each of which emits a wavelength different from the remaining lasers. Each of the plurality of lasers are in optical communication with a common beam expander providing the incident beam with a plurality of wavelengths of light. The common beam expander has optical properties that introduce axial chromatic aberrations to cancel axial chromatic aberrations introduced by the objective lens, with respect to the incident beam.