An imaging apparatus is provided to facilitate epifluorescent imaging of three (or more) color channels and to perform phase contrast and/or bright field imaging of samples without manual adjustment of the imaging apparatus. This allows for automated imaging, over extended periods of time, of a plurality of samples by a device located inside an incubator without disturbing the incubator environment to manually adjust the apparatus. Also provided are embodiments to facilitate user swapping of removable optical modules and/or transillumination modules to allow the imaging apparatus to be adapted to different combinations of assays and/or fluorescent indicators so as to increase the variety of experiments and/or fluorescent dyes that can be imaged using the imaging apparatus.