Inverted widefield microscope designed for single cell calcium measurements. It is equipped with a Lambda-DG4 xenon lamp, allowing fast wavelength switching. Additionally, its sensitive cooled CCD camera (Roper Scientific CoolSnap EQ CCD) allows you to capture weak fluorescent signals and minimize photobleaching/ photodamage in light sensitive samples. The MetaFluor Imaging Software is designed for dual-wavelength intracellular ion measurements. The software allows simultaneous display of the raw data; ratio image; graphs of intensities, ratios, and ion concentration. Two different indicators can be imaged and measured simultaneously to provide greater insight to ion exchange and intracellular function regardless of dye loading concentrations, conditions, or emission intensities.