According to one aspect of the invention, a wide-field microscope includes a stage configured to hold a specimen having a fluorescent material therein, and a multi-photon excitation light source configured to produce a substantially parallel beam of excitation light having a single photon energy less than an absorption energy required for single photon excitation of the fluorescent material. An infinity corrected objective is optically coupled to the multi-photon excitation light source and configured to focus the substantially parallel beam of excitation light onto the specimen such that multi-photon excitation of the fluorescent material simultaneously occurs over a predetermined area of the specimen. A focus lens is configured to focus emission light emitted from the predetermined area of the specimen onto at least two pixels of an image detector simultaneously. A focus lens is configured to focus emission light emitted from the predetermined area of the specimen onto an image plane, such that the image plane can be viewed through a binocular eyepiece or an imaging array detector.